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• Are there programs that iteratively write new programs?

  - by chris

  For about a year I have been thinking about writing a program that writes programs. This would primarily be a playful exercise that might teach me some new concepts. My inspiration came from negentropy and the ability for order to emerge from chaos and new chaos to arise out of order in infinite succession. To be more specific, the program would start by writing a short random string. If the string compiles the programs will log it for later comparison. If the string does not compile the program will try to rewrite it until it does compile. As more strings (mini 'useless' programs) are logged they can be parsed for similarities and used to generate a grammar. This grammar can then be drawn on to write more strings that have a higher probability of compilation than purely random strings. This is obviously more than a little silly, but I thought it would be fun to try and grow a program like this. And as a byproduct I get a bunch of unique programs that I can visualize and call art. I'll probably write this in Ruby due to its simple syntax and dynamic compilation and then I will visualize in processing using ruby-processing. What I would like to know is: Is there a name for this type of programming? What currently exists in this field? Who are the primary contributors? BONUS! - In what ways can I procedurally assign value to output programs beyond compiles(y/n)? I may want to extend the functionality of this program to generate a program based on parameters, but I want the program to define those parameters through running the programs that compile and assigning meaning to the programs output. This question is probably more involved than reasonable for a bonus, but if you can think of a simple way to get something like this done in less than 23 lines or one hyperlink, please toss it into your response. I know that this is not quite meta-programming and from the little I know of AI and generative algorithms they are usually more goal oriented than what I am thinking. What would be optimal is a program that continually rewrites and improves itself so I don't have to ^_^

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• Passing Info From One View to Another

  - by 01010011

  EDIT 1. The results of a query from my database are displayed on my view page. Next to each unique result is a button: // first_view.php <?php echo form_open('controller/method'); ?> <?php foreach($results_found as $item): ?> <p><?php echo $item->name ?></p> <p><?php form_submit('buy','Buy This'); ?></p> When a user clicks on one of these buttons (lets say button 4), I would like to display the user's choice from the array onto another view. I've tried using this: // first_view.php <?php echo $this->session->set_userdata('choice',$item); ?> immediately before // first_view.php <?php echo form_close(); ?> thinking that the user's final choice would be stored there so I can display it on another view like this: // second_controller.php $c = $this->session->userdata('choice'); // second_view.php echo 'Your Choose: '. $c; However, what actually displays is the last result displayed on first_view.php, not what the user choose. My question is, if the user clicked on button 4, how do I get that particular choice displayed onto another view? END OF EDIT1 ORIGINAL QUESTION My view page (CodeIgniter) displays the contents of an array in the form of several links. If a user clicks on a link, I want the user to be taken to another view page (via a controller) that gives more information concerning that particular link (which is stored in that particular position in the array) My question is, how do I access and display the contents of that particular location within the array on the second view file without getting a "Undefined variable error" on the second view? Here is what I am trying to do in code form // my_controller.php $array_name['variable_name']; $this->load->view('first_view.php'); // first_view.php <?php foreach($variable_name as $vn): ?> <?php echo anchor('controller_name' $vn->info ?> // if user clicks on 3rd link <?php endforeach ?> // I want to beable to access // index 2 of the array in the // second view file so I can // display more info // second_view.php <?php $vn[2]->info ?>

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• How can I structure and recode messy categorical data in R?

  - by briandk

  I'm struggling with how to best structure categorical data that's messy, and comes from a dataset I'll need to clean. The Coding Scheme I'm analyzing data from a university science course exam. We're looking at patterns in student responses, and we developed a coding scheme to represent the kinds of things students are doing in their answers. A subset of the coding scheme is shown below. Note that within each major code (1, 2, 3) are nested non-unique sub-codes (a, b, ...). What the Raw Data Looks Like I've created an anonymized, raw subset of my actual data which you can view here. Part of my problem is that those who coded the data noticed that some students displayed multiple patterns. The coders' solution was to create enough columns (reason1, reason2, ...) to hold students with multiple patterns. That becomes important because the order (reason1, reason2) is arbitrary--two students (like student 41 and student 42 in my dataset) who correctly applied "dependency" should both register in an analysis, regardless of whether 3a appears in the reason column or the reason2 column. How Can I Best Structure Student Data? Part of my problem is that in the raw data, not all students display the same patterns, or the same number of them, in the same order. Some students may do just one thing, others may do several. So, an abstracted representation of example students might look like this: Note in the example above that student002 and student003 both are coded as "1b", although I've deliberately shown the order as different to reflect the reality of my data. My (Practical) Questions Should I concatenate reason1, reason2, ... into one column? How can I (re)code the reasons in R to reflect the multiplicity for some students? Thanks I realize this question is as much about good data conceptualization as it is about specific features of R, but I thought it would be appropriate to ask it here. If you feel it's inappropriate for me to ask the question, please let me know in the comments, and stackoverflow will automatically flood my inbox with sadface emoticons. If I haven't been specific enough, please let me know and I'll do my best to be clearer.

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• LinqToXML why does my object go out of scope? Also should I be doing a group by?

  - by Kettenbach

  Hello All, I have an IEnumerable<someClass>. I need to transform it into XML. There is a property called 'ZoneId'. I need to write some XML based on this property, then I need some decendent elements that provide data relevant to the ZoneId. I know I need some type of grouping. Here's what I have attempted thus far without much success. **inventory is an IEnumerable<someClass>. So I query inventory for unique zones. This works ok. var zones = inventory.Select(c => new { ZoneID = c.ZoneId , ZoneName = c.ZoneName , Direction = c.Direction }).Distinct(); No I want to create xml based on zones and place. ***place is a property of 'someClass'. var xml = new XElement("MSG_StationInventoryList" , new XElement("StationInventory" , zones.Select(station => new XElement("station-id", station.ZoneID) , new XElement("station-name", station.ZoneName)))); This does not compile as "station" is out of scope when I try to add the "station-name" element. However is I remove the paren after 'ZoneId', station is in scope and I retreive the station-name. Only problem is the element is then a decendant of 'station-id'. This is not the desired output. They should be siblings. What am I doing wrong? Lastly after the "station-name" element, I will need another complex type which is a collection. Call it "places'. It will have child elements called "place". its data will come from the IEnumerable and I will only want "places" that have the "ZoneId" for the current zone. Can anyone point me in the right direction? Is it a mistake select distinct zones from the original IEnumerable? This object has all the data I need within it. I just need to make it heirarchical. Thanks for any pointers all. Cheers, Chris in San Diego

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• Symfony : ajax call cause server to queue next queries

  - by Remiz

  Hello, I've a problem with my application when an ajax call on the server takes too much time : it queue all the others queries from the user until it's done server side (I realized that canceling the call client side has no effect and the user still have to wait). Here is my test case : <script type="text/javascript" src="jquery-1.4.1.min.js"></script> <a href="another-page.php">Go to another page on the same server</a> <script type="text/javascript"> url = 'http://localserver/some-very-long-complex-query'; $.get(url); </script> So when the get is fired and then after I click on the link, the server finish serving the first call before bringing me to the other page. My problem is that I want to avoid this behavior. I'm on a LAMP server and I'm looking in a way to inform the server that the user aborted the query with function like connection_aborted(), do you think that's the way to go ? Also, I know that the longest part of this PHP script is a MySQL query, so even if I know that connection_aborted() can detect that the user cancel the call, I still need to check this during the MySQL query... I'm not really sure that PHP can handle this kind of "event". So if you have any better idea, I can't wait to hear it. Thank you. Update : After further investigation, I found that the problem happen only with the Symfony framework (that I omitted to precise, my bad). It seems that an Ajax call lock any other future call. It maybe related to the controller or the routing system, I'm looking into it. Also for those interested by the problem here is my new test case : -new project with Symfony 1.4.3, default configuration, I just created an app and a default module. -jquery 1.4 for the ajax query. Here is my actions.class.php (in my unique module) : class defaultActions extends sfActions { public function executeIndex(sfWebRequest $request) { //Do nothing } public function executeNewpage() { //Do also nothing } public function executeWaitingaction(){ // Wait sleep(30); return false; } } Here is my indexSuccess.php template file : <script type="text/javascript" src="jquery-1.4.1.min.js"></script> <a href="<?php echo url_for('default/newpage');?>">Go to another symfony action</a> <script type="text/javascript"> url = '<?php echo url_for('default/waitingaction');?>'; $.get(url); </script> For the new page template, it's not very relevant... But with this, I'm able to reproduce the lock problem I've on my real application. Is somebody else having the same issue ? Thanks.

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• Constructor versus setter injection

  - by Chris

  Hi, I'm currently designing an API where I wish to allow configuration via a variety of methods. One method is via an XML configuration schema and another method is through an API that I wish to play nicely with Spring. My XML schema parsing code was previously hidden and therefore the only concern was for it to work but now I wish to build a public API and I'm quite concerned about best-practice. It seems that many favor javabean type PoJo's with default zero parameter constructors and then setter injection. The problem I am trying to tackle is that some setter methods implementations are dependent on other setter methods being called before them in sequence. I could write anal setters that will tolerate themselves being called in many orders but that will not solve the problem of a user forgetting to set the appropriate setter and therefore the bean being in an incomplete state. The only solution I can think of is to forget about the objects being 'beans' and enforce the required parameters via constructor injection. An example of this is in the default setting of the id of a component based on the id of the parent components. My Interface public interface IMyIdentityInterface { public String getId(); /* A null value should create a unique meaningful default */ public void setId(String id); public IMyIdentityInterface getParent(); public void setParent(IMyIdentityInterface parent); } Base Implementation of interface: public abstract class MyIdentityBaseClass implements IMyIdentityInterface { private String _id; private IMyIdentityInterface _parent; public MyIdentityBaseClass () {} @Override public String getId() { return _id; } /** * If the id is null, then use the id of the parent component * appended with a lower-cased simple name of the current impl * class along with a counter suffix to enforce uniqueness */ @Override public void setId(String id) { if (id == null) { IMyIdentityInterface parent = getParent(); if (parent == null) { // this may be the top level component or it may be that // the user called setId() before setParent(..) } else { _id = Helpers.makeIdFromParent(parent,getClass()); } } else { _id = id; } } @Override public IMyIdentityInterface getParent() { return _parent; } @Override public void setParent(IMyIdentityInterface parent) { _parent = parent; } } Every component in the framework will have a parent except for the top level component. Using the setter type of injection, then the setters will have different behavior based on the order of the calling of the setters. In this case, would you agree, that a constructor taking a reference to the parent is better and dropping the parent setter method from the interface entirely? Is it considered bad practice if I wish to be able to configure these components using an IoC container? Chris

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• Sending HTML email from PHP

  - by KevinM

  I am trying to send a simple HTML e-mail from PHP. The code below simply results in a blank e-mail in GMail. It also has an empty attachment called 'noname', which is not at all what I want; though that might just be a symptom of it not working. The code I am using is: <?php //define the receiver of the email $to = '[email protected]'; //define the subject of the email $subject = 'Test HTML email'; //create a boundary string. It must be unique //so we use the MD5 algorithm to generate a random hash $random_hash = md5(date('r', time())); //define the headers we want passed. Note that they are separated with \r\n $headers = "From: [email protected]\r\nReply-To: [email protected]"; //add boundary string and mime type specification $headers .= "\r\nContent-Type: multipart/alternative; boundary=\"PHP-alt-".$random_hash."\""; //define the body of the message. ob_start(); //Turn on output buffering ?> --PHP-alt-<?php echo $random_hash; ?> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Hello World!!! This is simple text email message. --PHP-alt-<?php echo $random_hash; ?> MIME-Version: 1.0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: 7bit <h2>Hello World!</h2> <p>This is something with <b>HTML</b>formatting.</p> --PHP-alt-<?php echo $random_hash; ?>-- <? //copy current buffer contents into $message variable and delete current output buffer $message = ob_get_clean(); //send the email $mail_sent = @mail( $to, $subject, $message, $headers ); //if the message is sent successfully print "Mail sent". Otherwise print "Mail failed" echo $mail_sent ? "Mail sent" : "Mail failed";

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• HTTP caching confusion

  - by Keith

  I'm not sure whether this is a server issue, or whether I'm failing to understand how HTTP caching really works. I have an ASP MVC application running on IIS7. There's a lot of static content as part of the site including lots of CSS, Javascript and image files. For these files I want the browser to cache them for at least a day - our .css, .js, .gif and .png files rarely change. My web.config goes like this: <system.webServer> <staticContent> <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="1.00:00:00" /> </staticContent> </system.webServer> The problem I'm getting is that the browser (tested Chrome, IE8 and FX) doesn't seem to be caching the files as I'd expect. I've got the default settings (check for newer pages automatically in IE). On first visit the content downloads as expected HTTP/1.1 200 OK Cache-Control: max-age=86400 Content-Type: image/gif Last-Modified: Fri, 07 Aug 2009 09:55:15 GMT Accept-Ranges: bytes ETag: "3efeb2294517ca1:0" Server: Microsoft-IIS/7.0 X-Powered-By: ASP.NET Date: Mon, 07 Jun 2010 14:29:16 GMT Content-Length: 918 <content> I think that the Cache-Control: max-age=86400 should tell the browser not to request the page again for a day. Ok, so now the page is reloaded and the browser requests the image again. This time it gets an empty response with these headers: HTTP/1.1 304 Not Modified Cache-Control: max-age=86400 Last-Modified: Fri, 07 Aug 2009 09:55:15 GMT Accept-Ranges: bytes ETag: "3efeb2294517ca1:0" Server: Microsoft-IIS/7.0 X-Powered-By: ASP.NET Date: Mon, 07 Jun 2010 14:30:32 GMT So it looks like the browser has sent the ETag back (as a unique id for the resource), and the server's come back with a 304 Not Modified - telling the browser that it can use the previously downloaded file. It seems to me that would be correct for many caching situations, but here I don't want the extra round trip. I don't care if the image gets out of date when the file on the server changes. There are a lot of these files (even with sprite-maps and the like) and many of our clients have very slow networks. Each round trip to ping for that 304 status is taking about a 10th to a 5th of a second. Many also have IE6 which only has 2 HTTP connections at a time. The net result is that our application appears to be very slow for these clients with every page taking an extra couple of seconds to check that the static content hasn't changed. What response header am I missing that would cause the browser to aggressively cache the files? How would I set this in a .Net web.config for IIS7? Am I misunderstanding how HTTP caching works in the first place?

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• How do I recover from an unchecked exception?

  - by erickson

  Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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• How to optimize this SQL query for a rectangular region?

  - by Andrew B.

  I'm trying to optimize the following query, but it's not clear to me what index or indexes would be best. I'm storing tiles in a two-dimensional plane and querying for rectangular regions of that plane. The table has, for the purposes of this question, the following columns: id: a primary key integer world_id: an integer foreign key which acts as a namespace for a subset of tiles tileY: the Y-coordinate integer tileX: the X-coordinate integer value: the contents of this tile, a varchar if it matters. I have the following indexes: "ywot_tile_pkey" PRIMARY KEY, btree (id) "ywot_tile_world_id_key" UNIQUE, btree (world_id, "tileY", "tileX") "ywot_tile_world_id" btree (world_id) And this is the query I'm trying to optimize: ywot=> EXPLAIN ANALYZE SELECT * FROM "ywot_tile" WHERE ("world_id" = 27685 AND "tileY" <= 6 AND "tileX" <= 9 AND "tileX" >= -2 AND "tileY" >= -1 ); QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------- Bitmap Heap Scan on ywot_tile (cost=11384.13..149421.27 rows=65989 width=168) (actual time=79.646..80.075 rows=96 loops=1) Recheck Cond: ((world_id = 27685) AND ("tileY" <= 6) AND ("tileY" >= (-1)) AND ("tileX" <= 9) AND ("tileX" >= (-2))) -> Bitmap Index Scan on ywot_tile_world_id_key (cost=0.00..11367.63 rows=65989 width=0) (actual time=79.615..79.615 rows=125 loops=1) Index Cond: ((world_id = 27685) AND ("tileY" <= 6) AND ("tileY" >= (-1)) AND ("tileX" <= 9) AND ("tileX" >= (-2))) Total runtime: 80.194 ms So the world is fixed, and we are querying for a rectangular region of tiles. Some more information that might be relevant: All the tiles for a queried region may or may not be present The height and width of a queried rectangle are typically about 10x10-20x20 For any given (world, X) or (world, Y) pair, there may be an unbounded number of matching tiles, but the worst case is currently around 10,000, and typically there are far fewer. New tiles are created far less frequently than existing ones are updated (changing the 'value'), and that itself is far less frequent that just reading as in the query above. The only thing I can think of would be to index on (world, X) and (world, Y). My guess is that the database would be able to take those two sets and intersect them. The problem is that there is a potentially unbounded number of matches for either for either of those. Is there some other kind of index that would be more appropriate?

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• Compose synthetic English phrase that would contain 160 bits of recoverable information

  - by Alexander Gladysh

  I have 160 bits of random data. Just for fun, I want to generate pseudo-English phrase to "store" this information in. I want to be able to recover this information from the phrase. Note: This is not a security question, I don't care if someone else will be able to recover the information or even detect that it is there or not. Criteria for better phrases, from most important to the least: Short Unique Natural-looking The current approach, suggested here: Take three lists of 1024 nouns, verbs and adjectives each (picking most popular ones). Generate a phrase by the following pattern, reading 20 bits for each word: Noun verb adjective verb, Noun verb adjective verb, Noun verb adjective verb, Noun verb adjective verb. Now, this seems to be a good approach, but the phrase is a bit too long and a bit too dull. I have found a corpus of words here (Part of Speech Database). After some ad-hoc filtering, I calculated that this corpus contains, approximately 50690 usable adjectives 123585 nouns 15301 verbs This allows me to use up to 16 bits per adjective (actually 16.9, but I can't figure how to use fractional bits) 15 bits per noun 13 bits per verb For noun-verb-adjective-verb pattern this gives 57 bits per "sentence" in phrase. This means that, if I'll use all words I can get from this corpus, I can generate three sentences instead of four (160 / 57 ˜ 2.8). Noun verb adjective verb, Noun verb adjective verb, Noun verb adjective verb. Still a bit too long and dull. Any hints how can I improve it? What I see that I can try: Try to compress my data somehow before encoding. But since the data is completely random, only some phrases would be shorter (and, I guess, not by much). Improve phrase pattern, so it would look better. Use several patterns, using the first word in phrase to somehow indicate for future decoding which pattern was used. (For example, use the last letter or even the length of the word.) Pick pattern according to the first bytes of the data. ...I'm not that good with English to come up with better phrase patterns. Any suggestions? Use more linguistics in the pattern. Different tenses etc. ...I guess, I would need much better word corpus than I have now for that. Any hints where can I get a suitable one?

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• many-to-many performance concerns with fluent nhibernate.

  - by Ciel

  I have a situation where I have several many-to-many associations. In the upwards of 12 to 15. Reading around I've seen that it's generally believed that many-to-many associations are not 'typical', yet they are the only way I have been able to create the associations appropriate for my case, so I'm not sure how to optimize any further. Here is my basic scenario. class Page { IList<Tag> Tags { get; set; } IList<Modification> Modifications { get; set; } IList<Aspect> Aspects { get; set; } } This is one of my 'core' classes, and coincidentally one of my core tables. Virtually half of the objects in my code can have an IList<Page>, and some of them have IList<T> where T has its own IList<Page>. As you can see, from an object oriented standpoint, this is not really a problem. But from a database standpoint this begins to introduce a lot of junction tables. So far it has worked fine for me, but I am wondering if anyone has any ideas on how I could improve on this structure. I've spent a long time thinking and in order to achieve the appropriate level of association required, I cannot think of any way to improve it. The only thing I have come up with is to make intermediate classes for each object that has an IList<Page>, but that doesn't really do anything that the HasManyToMany does not already do except introduce another class. It does not extend the functionality and, from what I can tell, it does not improve performance. Any thoughts? I am also concerned about Primary Key limits in this scenario. Most everything needs to be able to have these properties, but the Pages cannot be unique to each object, because they are going to be frequently shared and joined between multiple objects. All relationships are one-sided. (That is, a Page has no knowledge of what owns it). Because of this, I also have no Inverse() mapped HasManyToMany collections. Also, I have read the similar question : Usage of ORMs like NHibernate when there are many associations - performance concerns But it really did not answer my concerns.

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• Mysterious constraints problem with SQL Server 2000

  - by Ramon

  Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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• Array within Form collecting multiple values with the same name possible?

  - by JM4

  Good afternoon, I will first start with the goal I am trying to accomplish and then give a very basic sample of what I need to do. Goal Instead of collecting several variables and naming them with keys individually, I have decided to give in and use an array structure to handle all inputs of the same type and rules. Once I have the variables, I will validate against them and if 'ok' store them in a MySQL table. The table will hold consumer information and will need to store multiple rows of the same type of information. First Pass I will leave out the validation portion of this question because I feel I need to first understand the basics. <form action="?" method="POST" name="Form"> Member 1 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 1 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 1 Email: <input type="text" name="MemberEmail[]" /><br /> Member 2 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 2 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 2 Email: <input type="text" name="MemberEmail[]" /><br /> Member 3 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 3 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 3 Email: <input type="text" name="MemberEmail[]" /><br /> <input type="submit" name="submit" value="Continue" /> </form> I am hoping that each input given for First Name (a required field) will generate a unique key for that particular entry and not overwrite any data entered. Because I am carrying information from page to page (checkout form), I am turning the POST variables into SESSION variables then storing in a mysql database in the end. My hope is to have: <?php $conn = mysql_connect("localhost", "username", "password"); mysql_select_db("DBname",$conn); $sql = "INSERT INTO tablename VALUES ('$_SESSION[Member1FirstName]', '$_SESSION[Member1LastName]', '$_SESSION[Member1Email]', '$_SESSION[Member2FirstName]', '$_SESSION[Member2LastName]', '$_SESSION[Member2Email]', '$_SESSION[Member1FirstName]', '$_SESSION[Member3LastName]', '$_SESSION[Member3Email]')"; $result = mysql_query($sql, $conn) or die(mysql_error()); Header ("Location: completed.php"); ?> Where Member1, Member2, and Member3 values will appear on their own row within the table. I KNOW my code is wrong but I am giving a first shot at the overall business purpose I am trying to achieve and trying to learn how to code the right way. I am very, very new to programming so any 'baby advice' is greatly appreciated.

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• Nhibernate: mapping two different properties between the same 2 entities

  - by Carlos Decas

  I have a Class A: public class ClassA { public int ID {get; private set;} public string Code {get; private set;} public ClassB B {get; private set;} public IList<ClassB> ListB {get; private set;} } And a ClassB: public class ClassB { public int ID {get; private set;} public string Code {get; private set;} public ClassA A {get; private set;} //some other attributes... } And the Mappings: public ClassAMap() { Table("ClassA"); Id(classA => classA .ID, "ID").GeneratedBy.Identity(); Map(classA => classA.Code, "Code").Unique().Not.Nullable(); //HERE IS THE PROBLEM: -------- References(classA => classA.B,"IDClassB").Cascade.SaveUpdate(); //----- HasMany(classA => classA.ListB).Table("ClassB").KeyColumn("IDClassA").AsBag().Not.LazyLoad().Inverse().Cascade.AllDeleteOrphan(); } ClassB Mappings: public ClassBMap() { Table("ClassB"); Id(classB => classB.ID).GeneratedBy.Identity(); References(classB => classB.A, "IDClassA").ForeignKey("ID").Cascade.SaveUpdate(); } The mappings for ListB in classA worked ok, because at first the was only ListB property and not B, when i had to map B i tried this: References(classA => classA.B,"IDClassB"); The mapping test failed because B wasn't saved, so i did this: References(classA => classA.B,"IDClassB").Cascade.SaveUpdate(); This time B was saved, but by saving B, classA was inserted two times, by A.B and by B.A. How can i solve this problem? Why does it work for the ListB property and not for the B property? Thanks

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• How to Sync CI (Hudson) Activity into an existing automated Build Process (phing, svn)?

  - by maraspin

  OUR CURRENT BUILD PROCESS We're a small team of developers (2 to 4 people depending on project) who currently use Phing to deploy code to a staging environment, before going live. We keep our code in a SVN repo, where the trunk holds current active development and, at certain times, we do make branches that we test and then (if successful), tag and export to the staging env. If everything goes well there too, we finally deploy'em in production servers. Actions are highly automated, but always triggered by human intervention. THE DOUBT We'd now like to introduce Continuous Integration (with Hudson) in the process; unfortunately we have a few doubts about activity syncing, since we're afraid that CI could somewhat interfere with our build process and cause certain problems. Considering that an automated CI cycle has a certain frequency of automatically executed actions, we see 2 possible cases for "integration", each with its own problems: Case A: each CI cycle produces a new branch with its own name; we do use such a name to manually (through phing as it happens now) export the code from the SVN to the staging env. The problem I see here is that (unless specific countermeasures are taken - IE deletion) the number of branches we have can easily grow out of control (let's suppose we commit often, so that we have a fresh new build/branch every N minutes). Case B: each CI cycle creates a new branch named 'current', which is then tagged with a unique name only when we manually decide to export it to staging; the current branch, at any case is then deleted, as soon as the next CI cycle starts up. The problem we see here is that a new cycle could kick in while someone is tagging/exporting the 'current' branch to staging thus creating an inconsistent build (but maybe here I'm just too pessimist, since I confess I don't know whether SVN offers some built-in protection against this). With all this being said, I was wondering if anyone with similar experiences could be so kind to give us some hints on the subject, since none of the approaches depicted above looks completely satisfing to us. Is there something important we just completely left off in the overall picture? Thanks for your attention & (in advance) for your help!

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• Sort/Group XML data with PHP?

  - by Volmar

  I'm trying to make a page using data from the discogs.com (XML)-API. i've been parsing it with simpleXML and it's working pretty well but there is some things i'm not sure how to do. Here is part of the XML: <releases> <release id="1468764" status="Accepted" type="Main"> <title>Versions</title> <format>12", EP</format> <label>Not On Label</label> <year>1999</year> </release> <release id="72246" status="Accepted" type="Main"> <title>The M.O.F Blend</title> <format>LP</format> <label>Blenda Records</label> <year>2002</year> </release> <release id="890064" status="Accepted" type="Main"> <title>The M.O.F Blend</title> <format>CD</format> <label>Blenda Records</label> <year>2002</year> </release> <release id="1563561" status="Accepted" type="TrackAppearance"> <title>Ännu En Gång Vol. 3</title> <trackinfo>Backtrack</trackinfo> <format>Cass, Comp, Mix</format> <label>Hemmalaget</label> <year>2001</year> </release> </releases> What i want to achieve is something similair to how discogs presents the releases: http://www.discogs.com/artist/Mics+Of+Fury where diferent versions of the same release are sorted together. (see. The M.O.F Blend in my link) This is done on discogs with having a master release that features the other releases. unfortunately this information isn't present in the API data, so i want to do the same thing by grouping the <release>-nodes with the same <title>-tags, or add a flag to the <releases> that don't have a unique <title>? any good ideas on the best way of doing this? i also like to know if it's possible to count the <release>-nodes (child of releases) that have the same type-attribute? like in this example count the releases with the type "Main"? maybe it's better to do this things with XMLReader or XPath?

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• How do I classify using SVM Classifier?

  - by Gomathi

  I'm doing a project in liver tumor classification. Actually I initially used Region Growing method for liver segmentation and from that I segmented tumor using FCM. I,then, obtained the texture features using Gray Level Co-occurence Matrix. My output for that was stats = autoc: [1.857855266614132e+000 1.857955341199538e+000] contr: [5.103143332457753e-002 5.030548650257343e-002] corrm: [9.512661919561399e-001 9.519459060378332e-001] corrp: [9.512661919561385e-001 9.519459060378338e-001] cprom: [7.885631654779597e+001 7.905268525471267e+001] Now how should I give this as an input to the SVM program. function [itr] = multisvm( T,C,tst ) %MULTISVM(2.0) classifies the class of given training vector according to the % given group and gives us result that which class it belongs. % We have also to input the testing matrix %Inputs: T=Training Matrix, C=Group, tst=Testing matrix %Outputs: itr=Resultant class(Group,USE ROW VECTOR MATRIX) to which tst set belongs %----------------------------------------------------------------------% % IMPORTANT: DON'T USE THIS PROGRAM FOR CLASS LESS THAN 3, % % OTHERWISE USE svmtrain,svmclassify DIRECTLY or % % add an else condition also for that case in this program. % % Modify required data to use Kernel Functions and Plot also% %----------------------------------------------------------------------% % Date:11-08-2011(DD-MM-YYYY) % % This function for multiclass Support Vector Machine is written by % ANAND MISHRA (Machine Vision Lab. CEERI, Pilani, India) % and this is free to use. email: [email protected] % Updated version 2.0 Date:14-10-2011(DD-MM-YYYY) u=unique(C); N=length(u); c4=[]; c3=[]; j=1; k=1; if(N>2) itr=1; classes=0; cond=max(C)-min(C); while((classes~=1)&&(itr<=length(u))&& size(C,2)>1 && cond>0) %This while loop is the multiclass SVM Trick c1=(C==u(itr)); newClass=c1; svmStruct = svmtrain(T,newClass); classes = svmclassify(svmStruct,tst); % This is the loop for Reduction of Training Set for i=1:size(newClass,2) if newClass(1,i)==0; c3(k,:)=T(i,:); k=k+1; end end T=c3; c3=[]; k=1; % This is the loop for reduction of group for i=1:size(newClass,2) if newClass(1,i)==0; c4(1,j)=C(1,i); j=j+1; end end C=c4; c4=[]; j=1; cond=max(C)-min(C); % Condition for avoiding group %to contain similar type of values %and the reduce them to process % This condition can select the particular value of iteration % base on classes if classes~=1 itr=itr+1; end end end end Kindly guide me. Images:

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• JSF 2.0: Preserving component state across multiple views

  - by tlind

  The web application I am developing using MyFaces 2.0.3 / PrimeFaces 2.2RC2 is divided into a content and a navigation area. In the navigation area, which is included into multiple pages using templating (i.e. <ui:define>), there are some widgets (e.g. a navigation tree, collapsible panels etc.) of which I want to preserve the component state across views. For example, let's say I am on the home page. When I navigate to a product details page by clicking on a product in the navigation tree, my Java code triggers a redirect using navigationHandler.handleNavigation(context, null, "/detailspage.jsf?faces-redirect=true") Another way of getting to that details page would be by directly clicking on a product teaser that is shown on the home page. The corresponding <h:link> would lead us to the details page. In both cases, the expansion state of my navigation tree (a PrimeFaces tree component) and my collapsible panels is lost. I understand this is because the redirect / h:link results in the creation of a new view. What is the best way of dealing with this? I am already using MyFaces Orchestra in my project along with its conversation scope, but I am not sure if this is of any help here (since I'd have to bind the expansion/collapsed state of the widgets to a backing bean... but as far as I know, this is not possible). Is there a way of telling JSF which component states to propagate to the next view, assuming that the same component exists in that view? I guess I could need a pointer into the right direction here. Thanks! Update 1: I just tried binding the panels and the tree to a session-scoped bean, but this seems to have no effect. Also, I guess I would have to bind all child components (if any) manually, so this doesn't seem like the way to go. Update 2: Binding UI components to non-request scoped beans is not a good idea (see link I posted in a comment below). If there is no easier approach, I might have to proceed as follows: When a panel is collapsed or the tree is expanded, save the current state in a session-scoped backing bean (!= the UI component itself) The components' states are stored in a map. The map key is the component's (hopefully) unique, relative ID. I cannot use the whole absolute component path here, since the IDs of the parent naming containers might change if the view changes, assuming these IDs are generated programmatically. As soon as a new view gets constructed, retrieve the components' states from the map and apply them to the components. For example, in case of the panels, I can set the collapsed attribute to a value retrieved from my session-scoped backing bean.

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• Normalizing Item Names & Synonyms

  - by RabidFire

  Consider an e-commerce application with multiple stores. Each store owner can edit the item catalog of his store. My current database schema is as follows: item_names: id | name | description | picture | common(BOOL) items: id | item_name_id | picture | price | description | picture item_synonyms: id | item_name_id | name | error(BOOL) Notes: error indicates a wrong spelling (eg. "Ericson"). description and picture of the item_names table are "globals" that can optionally be overridden by "local" description and picture fields of the items table (in case the store owner wants to supply a different picture for an item). common helps separate unique item names ("Jimmy Joe's Cheese Pizza" from "Cheese Pizza") I think the bright side of this schema is: Optimized searching & Handling Synonyms: I can query the item_names & item_synonyms tables using name LIKE %QUERY% and obtain the list of item_name_ids that need to be joined with the items table. (Examples of synonyms: "Sony Ericsson", "Sony Ericson", "X10", "X 10") Autocompletion: Again, a simple query to the item_names table. I can avoid the usage of DISTINCT and it minimizes number of variations ("Sony Ericsson Xperia™ X10", "Sony Ericsson - Xperia X10", "Xperia X10, Sony Ericsson") The down side would be: Overhead: When inserting an item, I query item_names to see if this name already exists. If not, I create a new entry. When deleting an item, I count the number of entries with the same name. If this is the only item with that name, I delete the entry from the item_names table (just to keep things clean; accounts for possible erroneous submissions). And updating is the combination of both. Weird Item Names: Store owners sometimes use sentences like "Harry Potter 1, 2 Books + CDs + Magic Hat". There's something off about having so much overhead to accommodate cases like this. This would perhaps be the prime reason I'm tempted to go for a schema like this: items: id | name | picture | price | description | picture (... with item_names and item_synonyms as utility tables that I could query) Is there a better schema you would suggested? Should item names be normalized for autocomplete? Is this probably what Facebook does for "School", "City" entries? Is the first schema or the second better/optimal for search? Thanks in advance! References: (1) Is normalizing a person's name going too far?, (2) Avoiding DISTINCT

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• What are the weaknesses of this user authentication method?

  - by byronh

  I'm developing my own PHP framework. It seems all the security articles I have read use vastly different methods for user authentication than I do so I could use some help in finding security holes. Some information that might be useful before I start. I use mod_rewrite for my MVC url's. Passwords are sha1 and md5 encrypted with 24 character salt unique to each user. mysql_real_escape_string and/or variable typecasting on everything going in, and htmlspecialchars on everything coming out. Step-by step process: Top of every page: session_start(); session_regenerate_id(); If user logs in via login form, generate new random token to put in user's MySQL row. Hash is generated based on user's salt (from when they first registered) and the new token. Store the hash and plaintext username in session variables, and duplicate in cookies if 'Remember me' is checked. On every page, check for cookies. If cookies set, copy their values into session variables. Then compare $_SESSION['name'] and $_SESSION['hash'] against MySQL database. Destroy all cookies and session variables if they don't match so they have to log in again. If login is valid, some of the user's information from the MySQL database is stored in an array for easy access. So far, I've assumed that this array is clean so when limiting user access I refer to user.rank and deny access if it's below what's required for that page. I've tried to test all the common attacks like XSS and CSRF, but maybe I'm just not good enough at hacking my own site! My system seems way too simple for it to actually be secure (the security code is only 100 lines long). What am I missing? I've also spent alot of time searching for the vulnerabilities with mysql_real_escape string but I haven't found any information that is up-to-date (everything is from several years ago at least and has apparently been fixed). All I know is that the problem was something to do with encoding. If that problem still exists today, how can I avoid it? Any help will be much appreciated.

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• how to create a system-wide independent universal counter object primarily for Database keys?

  - by andora

  I would like to create/use a system-wide independent universal 'counter object' that can be called via COM in a thread-safe manner. The counter object will be passed an ID to identify which counter to return, handle the counting, 'persist' the count (occasionally), have reasonable performance (as fast as possible) perhaps capable of 1000 counts per second or better (1mS) and be accessible cross-process/out-of-process. The current count status must be persisted between object restarts/shutdowns. The counter object is liklely to be a 'singleton' type object implemented in some form of free-threaded dictionary, containing maybe 10 counters (perhaps 50 max). The count needs to be monotonic and consistent, (ie: guaranteed unique sequential values). Each counter should have a few methods, like reset, inc, dec, set, clear, remove. As a luxury, I would like to have a variable-increment (ie: 'step by' value). To support thread-safefty, perhaps some sorm of critical-section or mutex call. It just needs to return a long/4byte signed integer. I really want something that can be called from anywhere, including VBScript, so I figure COM is my preferred solution. The primary use of this is for database keys. I am unable to use autoinc or guid type keys and have ruled out database-generated counting systems at this point. I've spent days researching this and I have really struggled to find a solution. The best I can find is a free-threaded dictionary object that can be instantiated using COM+ from Motobit - it seems to offer all the 'basics' and I guess I could create some form of wrapper for this. So, here are my questions: Does such a 'general purpose counter-object already exist? Can you direct me to it? (MS did do an IIS/ASP object called 'MSWC.Counter' but this isn't 'cross-process'/ out-of-process component and isn't thread-safe. (but if it was, it would do!) What is the best way of creating such a Component? (I'd prefer VB6 right-now, [don't ask!] but can do in VB.NET2005 if I had to). I don't have the skills/knowledge/tools to use anything else. I am desparate for a workable solution. I need specific guidance! If anybody can code something up for me I am prepared to pay for it.

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• Android pluginable application

  - by Alxandr

  I've been trying to create an android-application the last couple of weeks, and mostly everything has worked out great, but there is one thing that I was wondering about, and that is pluginability trough the use of intents. What I'm trying to create is basically a comic-reader. As of the version I use now, I open the application and get a list of commics that are my favourites, then I enter one to get a detailed view, and finally I enter a page. This is managed trough 3 activities. List, Details and Page. However, as of now the application can only read comics of one source (a specialiced xml-feed comming from my server), and I was hoping to be able to expand this a litle (also, the page-activity and some other stuff needs to be cleaned up in, so I'm thinking about remaking from scratch, and just take the first go as a learning-round). And I came up with an idea which I think sounds great, but I don't know if it's possible, but this is what I'm thinking about: The user enters the application and get an (first time empty) list of comics. The user hits a button to find comics, this launces an intent that says something like "find comic" or something like that. This should cause the system to display all matching activities. This would make it possible to provide different comic-providers trough different applications. Another activity kicks in and might displays some options to the user (for instance a file-browser), or might not (in the example of an xml-feed, which should just load). The list is returned to the first activity and displayed to the user. The second (find) activity is closed. The user picks a comic from the list. This should open some details-activity. The details-activity should receive a key which corresponds to the comic selected. This should be unique amongst the comic-providers. The details-view should get it's data trough some cind of content-provider, or an activity (whichever is most suited, if one of them is). The user can select a page. This should be the same routine as step 5. My question is, is this possible in the android system, and if it is, is it a bad idea? And also, is there any better way to achieve more or less the same thing?

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• How does Sentry aggregate errors?

  - by Hugo Rodger-Brown

  I am using Sentry (in a django project), and I'd like to know how I can get the errors to aggregate properly. I am logging certain user actions as errors, so there is no underlying system exception, and am using the culprit attribute to set a friendly error name. The message is templated, and contains a common message ("User 'x' was unable to perform action because 'y'"), but is never exactly the same (different users, different conditions). Sentry clearly uses some set of attributes under the hood to determine whether to aggregate errors as the same exception, but despite having looked through the code, I can't work out how. Can anyone short-cut my having to dig further into the code and tell me what properties I need to set in order to manage aggregation as I would like? [UPDATE 1: event grouping] This line appears in sentry.models.Group: class Group(MessageBase): """ Aggregated message which summarizes a set of Events. """ ... class Meta: unique_together = (('project', 'logger', 'culprit', 'checksum'),) ... Which makes sense - project, logger and culprit I am setting at the moment - the problem is checksum. I will investigate further, however 'checksum' suggests that binary equivalence, which is never going to work - it must be possible to group instances of the same exception, with differenct attributes? [UPDATE 2: event checksums] The event checksum comes from the sentry.manager.get_checksum_from_event method: def get_checksum_from_event(event): for interface in event.interfaces.itervalues(): result = interface.get_hash() if result: hash = hashlib.md5() for r in result: hash.update(to_string(r)) return hash.hexdigest() return hashlib.md5(to_string(event.message)).hexdigest() Next stop - where do the event interfaces come from? [UPDATE 3: event interfaces] I have worked out that interfaces refer to the standard mechanism for describing data passed into sentry events, and that I am using the standard sentry.interfaces.Message and sentry.interfaces.User interfaces. Both of these will contain different data depending on the exception instance - and so a checksum will never match. Is there any way that I can exclude these from the checksum calculation? (Or at least the User interface value, as that has to be different - the Message interface value I could standardise.) [UPDATE 4: solution] Here are the two get_hash functions for the Message and User interfaces respectively: # sentry.interfaces.Message def get_hash(self): return [self.message] # sentry.interfaces.User def get_hash(self): return [] Looking at these two, only the Message.get_hash interface will return a value that is picked up by the get_checksum_for_event method, and so this is the one that will be returned (hashed etc.) The net effect of this is that the the checksum is evaluated on the message alone - which in theory means that I can standardise the message and keep the user definition unique. I've answered my own question here, but hopefully my investigation is of use to others having the same problem. (As an aside, I've also submitted a pull request against the Sentry documentation as part of this ;-)) (Note to anyone using / extending Sentry with custom interfaces - if you want to avoid your interface being use to group exceptions, return an empty list.)

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• Magento user created attribute for products is not saved...

  - by Elzo Valugi

  I am fighting an apparently simple thing for about two days now. I hope somebody can help. I created the myUpdate EAV attribute class Company_Module_Model_Resource_Eav_Mysql4_Setup extends Mage_Eav_Model_Entity_Setup { public function getDefaultEntities() { return array( 'catalog_product' => array( 'entity_model' => 'catalog/product', 'attribute_model' => 'catalog/resource_eav_attribute', 'table' => 'catalog/product', 'additional_attribute_table' => 'catalog/eav_attribute', 'entity_attribute_collection' => 'catalog/product_attribute_collection', 'attributes' => array( 'my_update' => array( 'label' => 'My timestamp', 'type' => 'datetime', 'input' => 'date', 'default' => '', 'class' => 'validate-date', 'backend' => 'eav/entity_attribute_backend_datetime', 'frontend' => '', 'table' => '', 'source' => '', 'global' => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL, 'visible' => true, 'required' => false, 'user_defined' => true, 'searchable' => false, 'filterable' => false, 'comparable' => false, 'visible_on_front' => false, 'visible_in_advanced_search' => false, 'unique' => false, 'apply_to' => 'simple', ) ) ) ); } } The attribute is created OK and on install appears correctly in the list of attributes. Later I do // for product 1 $product->setMyUpdate($stringDate); // string this format: yyyy-MM-dd HH:mm:ss $product->save(); // and saves without issues * in admin module But later when I do: $product = Mage::getModel('catalog/product')->load(1); var_dump($product->getMyUpdate()); // returns null Somehow the data is not really saved.. or I am not retrieving it correctly. Please advice on how to get the data and where the data is saved in the DB so I can check at if the insert is done correctly. Thanks.

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