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• Rails: Generated tokens missing occasionally

  - by Vincent Chan

  We generate an unique token for each user and store it on database. Everything is working fine in the local environment. However, after we upload the codes to the production server on Engine Yard, things become weird. We tried to register an account right after the deploy. It is working fine and we can see the token in the db. But after that, when we register new accounts, we cannot see any tokens. We only have NULL in the db. Not sure what caused this problem because we can't re-produce this in the local machine. Thanks for your help.

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• Linq In Clause & Predicate building

  - by Michael G

  I have two tables. Report and ReportData. ReportData has a constraint ReportID. How can I write my linq query to return all Report objects where the predicate conditions are met for ReportData? Something like this in SQL: SELECT * FROM Report as r Where r.ServiceID = 3 and r.ReportID IN (Select ReportID FROM ReportData WHERE JobID LIKE 'Something%') This is how I'm building my predicate: Expression<Func<ReportData, bool>> predicate = PredicateBuilder.True<ReportData>(); predicate = predicate.And(x => x.JobID.StartsWith(QueryConfig.Instance.DataStreamName)); var q = engine.GetReports(predicate, reportsDataContext); reports = q.ToList(); This is my query construction at the moment: public override IQueryable<Report> GetReports(Expression<Func<ReportData, bool>> predicate, LLReportsDataContext reportDC) { if (reportDC == null) throw new ArgumentNullException("reportDC"); var q = reportDC.ReportDatas.Where(predicate).Where(r => r.ServiceID.Equals(1)).Select(r => r.Report); return q; }

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• Why does C# not implement GetHashCode for Collections?

  - by Peterdk

  I am porting something from Java to C#. In Java the hashcode of a ArrayList depends on the items in it. In C# I always get the same hashcode from a List... Why is this? For some of my objects the hashcode needs to be different because the objects in their list property make the objects non-equal. I would expect that a hashcode is always unique for the object's state and only equals another hashcode when the object is equal. Am I wrong?

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• Oracle - Is there any effects of not having a primary key on a table ?

  - by Sathya

  We use sequence numbers for primary keys on the tables. There are some tables where we dont really use the primary key for any querying purpose. But, we have Indexes on other columns. These are non-unique indexes. The queries use these non-primary key columns in the WHERE conditions. So, I dont really see any benefit of having a primary key on such tables. My experience with SQL 2000 was that, it used to replicate tables which had some primary key. Otherwise it would not. I am using Oracle 10gR2. I would like to know if there are any such side-effects of having tables that dont have primary key.

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• "partial views" best practices for 'container' divs?

  - by ropstah

  What is the 'best' way to handle the html markup for partial views? (which are also refreshed using AJAX) The biggest issue I run into is where to place the 'container' div... Consider having a masterpage and a partial view. (class="" could be interchanged with id="" depending if the partial is guaranteed to be unique, however this isn't really important to the issue i think) Masterpage: <div id="place1" class="placeholder"> <!-- render partial --> </div> Partial: <div id="partial1" class="partial"> <!-- content --> </div> I feel that something isn't being done right. However I cannot remove the div in the masterpage, because I need that to 'encapsulate' the response from AJAX partial updates. And also I cannot move the div in the partial to the masterpage, because that would require to move 'partial' info to the masterpage... How do you handle this?

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• How do people manage changes to common library files stored across mutiple (Mercurial) repositories?

  - by mckoss

  This is perhaps not a question unique to Mercurial, but that's the SCM that I've been using most lately. I work on multiple projects and tend to copy source code for libraries or utilities from a previous project to get a leg up on starting a new project. The problem comes in when I want to merge all the changes I made in my latest project, back into a "master" copy of those shared library files. Since the files stored in disjoint repositories will have distinct version histories, Mercurial won't be able to perform an intelligent merge if I just copy the files back to the master repo (or even between two independent projects). I'm looking for an easy way to preserve the change history so I can merge library files back to the master with a minimum of external record keeping (which is one of the reasons I'm using SVN less as merges require remembering when copies were made across branches). Perhaps I need to do a bit more up-front organization of my repository to prepare for a future merge back to a common master.

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• Are concurrency issues possible when using the WCF Service Behavoir attribute set to ConcurrencyMode

  - by Brandon Linton

  We have a WCF service that makes a good deal of transactional NHibernate calls. Occasionally we were seeing SQL timeouts, even though the calls were updating different rows and the tables were set to row level locking. After digging into the logs, it looks like different threads were entering the same point in the code (our transaction using block), and an update was hanging on commit. It didn't make sense, though, because we believed that the following service class attribute was forcing a unique execution thread per service call: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.PerCall)] We recently changed the concurrency mode to ConcurrencyMode.Single and haven't yet run into any issues, but the bug was very difficult to reproduce (if anyone has any thoughts on flushing a bug like that out, let me know!). Anyway, that all brings me to my question: shouldn't an InstanceContextMode of PerCall enforce thread-safety within the service, even if the ConcurrencyMode is set to multiple? How would it be possible for two calls to be serviced by the same service instance? Thanks!

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• Why does MySQL autoincrement increase on failed inserts?

  - by Sorcy

  A co-worker just made me aware of a very strange MySQL behavior. Assuming you have a table with an auto_increment field and another field that is set to unique (e.g. a username-field). When trying to insert a row with a username thats already in the table the insert fails, as expected. Yet the auto_increment value is increased as can be seen when you insert a valid new entry after several failed attempts. For example, when our last entry looks like this... ID: 10 Username: myname ...and we try five new entries with the same username value on our next insert we will have created a new row like so: ID: 16 Username: mynewname While this is not a big problem in itself it seems like a very silly attack vector to kill a table by flooding it with failed insert requests, as the MySQL Reference Manual states: "The behavior of the auto-increment mechanism is not defined if [...] the value becomes bigger than the maximum integer that can be stored in the specified integer type." Is this expected behavior?

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• phonegap crossplatform redirection to local file

  - by Marco Gagliardi

  Hi I'm developing a phonegap + JQueryMobile app, which should be correctly executed on Android, iOs and WindowsPhone as well. I need to exploit an external service wich requires one callback url to redirect the app to in case of success, and one in case of error (pretty common situation. In my case both will be local files, say www/success.html and www/error.html). Of course I could write different paths for each device (e.g. file:///android_asset/www/success.html on Android), but i'm wondering if the framework provide a more simple elegant solution. So the questions is, how can i get a unique absolute URL wich allows me to perform a cross-platform HTTP redirection from a remote web page to a local file within a phonegap application? Thanks

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• How do i serlialize the product using php?

  - by Ibrahim Azhar Armar

  hi, i am building a real estate application where in it will store the properties and search it. the property will have different categories like (residential, commercial, industrial or agricultural). based upon the category i want to serailize each and every property listing . for example the property with id 1 belongs to resedential will have the serial code rs_SOMERANDOMUNIQUENUMBER. and for commercial it can be cm_SOMERANDOMUNIQUENUMBER and so on. for this my database table looks like this. CREATE TABLE IF NOT EXISTS `propSerials` ( `id` bigint(20) NOT NULL auto_increment, `serial` varchar(50) NOT NULL, `property_id` int(10) UNIQUE NOT NULL, PRIMARY KEY  (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; what would be the best possible format to store the serial with the prefix according to category? thank you

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• Selecting an element based on class and id in jquery - similar to an SQL query

  - by Ankur

  I want to select an element based on it's class and id, I have seen many similar questions on SO. Most of the users ask why would you ever want to do this - which is not very helpful, trust me, this is the simplest way of solving my UI problem, and it's a very unique and intereting UI related to making generic triple stores easily browsable. At the moment the jQUery looks like this: $(document).ready( function() { $(".predicates").hide(); $(".objects").hide(); $("#subject").click( function() { $("#predId, .predicates").toggle(); // this line } ); $("#predId").click( function() { $("#objId, .objects").toggle(); } ); }); The line I am really interested in is this $("#predId, .predicates").toggle(); how do I get the select to ensure that both #predId and .predicates are true, at the moment it seems that only one or the other has to be true. Is there something like an && operator?

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• Display field from another table in SQL

  - by Roland Bengtsson

  I'm a newbie with SQL... Now I want to do display some instances of AddrDistances from DevExpress CxGrid with SQL. Select Cast((DistanceAsMeters * 0.001) as Decimal(8,1)) DistanceAsKm, bold_id, created, fromAddress, toAddress From AddrDistance Where DistanceAsMeters = 0 and PseudoDistanceAsCostKm = 0 and not AddrDistance.bold_id in (select bold_id from DistanceQueryTask) Order By Created Desc This SQL is working and the result is: DistanceAsKM Bold_ID Created FromAddress ToAddress 0 134808 16.02.2010 121795 134570 0 121701 10.03.2010 120850 122991 The result I want is this: DistanceAsKM Bold_ID Created FromAddress ToAddress 0 134808 16.02.2010 Kalmar Stockholm 0 121701 10.03.2010 Falkenberg Oslo So the amount of rows is right but I want to replace the numbers in FromAddress and ToAddress with strings from another table. The numbers shows here is just the boldid. Every object in the database have an unique boldid. The addresses above is stored in table Address and it have a City field with the column and a boldid as a key. What should I write in SQL to get this right ? Is there something in the CxGrid that could help here ? Regards

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• MS Access Mark Duplicates in order of appearance - using the function RankOfDup: (SELECT Count(*) ...)

  - by veska stoyanova

  I'm trying to create Ranking that shows the sequence of agreements for the two fields Customers and Agreements. The number for agreements must be unique, whereas customers can repeat. The formula RankOfDup: (SELECT Count(*) FROM Data a WHERE a.customer=Data.customer And a.agreement >= Data.agreement) Works beautifully but after this query with columns Agreement, Customer and RankofDup, I need to create crosstab that transposes the RankofDub. It works when I make the table first and then create query but my data is too large so I'm trying to put the select query with the ranking in a crosstab query. However, when I try to do this Access gives error message that microsoft jet ... doesn't recognise Data.customer? Any ideas how I can fix this?

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• Drupal: Two-way communication between unregistered customer and admin

  - by Bryan Folds

  I need to setup a system where customers can choose to Request a Quote for a specific holiday package, where they will enter their personal details as well as their holiday requirements (number of rooms, etc.) and will then allow them to view a page which will have a threaded conversation between them and the admin (so the admin can reply to their quote request on the website). The problem is that most customers won't be registered when they want to request a quote, so I was thinking that the Request a Quote page could silently register the customer as a user (using their personal details) on the same page where it asks for their holiday requirements. The other option I can think of would be to not register them and just email them a unique URL where they can view their quote request and reply to the admin. Could you point me in the right direction on how to do either of those?

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• Quickly retrieve the subset of properties used in a huge collection in C#

  - by ccornet

  I have a huge Collection (which I can cast as an enumerable using OfType<()) of objects. Each of these objects has a Category property, which is drawn from a list somewhere else in the application. This Collection can reach sizes of hundreds of items, but it is possible that only, say, 6/30 of the possible Categories are actually used. What is the fastest method to find these 6 Categories? The size of the huge Collection discourages me from just iterating across the entire thing and returning all unique values, so is there a faster method of accomplishing this? Ideally I'd collect the categories into a List.

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• Does my Dictionary must use locking mechanism?

  - by theateist

  Many threads have access to summary. Each thread will have an unique key for accessing the dictionary; Dictionary<string, List<Result>> summary; Do I need locking for following operations? summary[key] = new List<Result>() summary[key].Add(new Result()); It seems that I don't need locking because each thread will access dictionary with different key, but won't the (1) be problematic because of adding concurrently new record to dictionary with other treads?

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• Remove Duplicates from JavaScript Array

  - by kramden88

  This seems like such a simple need but I've spent an inordinate amount of time trying to do this to no avail. I've looked at other questions on SO and I haven't found what I need. I have a very simple JavaScript array such as peoplenames = new Array("Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"); that may or may not contain duplicates and I need to simply remove the duplicates and put the unique values in a new array. That's it. I could point to all the codes that I've tried but I think it's useless because they don't work. If anyone has done this and can help me out I'd really appreciate it. JavaScript or jQuery solutions are both acceptable.

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• INSERT INTO ... SELECT FROM ... ON DUPLICATE KEY UPDATE

  - by dnagirl

  I'm doing an insert query where most of many columns would need to be updated to the new values if a unique key already existed. It goes something like this: INSERT INTO lee(exp_id, created_by, location, animal, starttime, endtime, entct, inact, inadur, inadist, smlct, smldur, smldist, larct, lardur, lardist, emptyct, emptydur) SELECT id, uid, t.location, t.animal, t.starttime, t.endtime, t.entct, t.inact, t.inadur, t.inadist, t.smlct, t.smldur, t.smldist, t.larct, t.lardur, t.lardist, t.emptyct, t.emptydur FROM tmp t WHERE uid=x ON DUPLICATE KEY UPDATE ...; //update all fields to values from SELECT, except for exp_id, created_by, location, animal, starttime, endtime I'm not sure what the syntax for the UPDATE clause should be. How do I refer to the current row from the SELECT clause?

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• How can I force a ListView with a custom panel to re-measure when the ListView width goes below the

  - by Scott Whitlock

  Sorry for the long winded question (I'm including background here). If you just want the question, go to the end. I have a ListView with a custom Panel implementation that I'm using to implement something similar to a WrapPanel, but not quite. I'm overriding the MeasureOverride and ArrangeOverride methods in the custom panel. If I do the naive implementation of a WrapPanel in the MeasureOverride method it doesn't work when the ListView is resized. Let's say the custom panel does a measure and the constraint is a width of 100 and let's say I have 3 items that are 40 wide each. The naive approach is to return a size of 80,80 but when I resize the window that the ListView is in, down to say 75, it just turns on the horizontal scrollbar and never calls measure or arrange again (it does keep measuring and arranging if the width is greater than 80). To get around this, I hard coded the measurement to only have a width of the widest item. Then in the arrange, it gives me more space than I asked for and I use as much horizontal space as I can before wrapping. If I resize the window smaller than the smallest item in the ListView, then it turns on the scrollbar, which is great. Unfortunately this is causing a big problem when I have one of these ListViews with a custom panel nested inside of another one. The outside one works ok, but I can't get the inside one to "take as much as it needs". It always sizes to the smallest item, and the only way around it is to set the MinWidth to be something greater than zero. Anyway, stepping back for a second, I think the real way to fix this is to go back to the Naive implementation of the WrapPanel but force it to re-measure when the ListView width goes below the Size I previously returned as a measurement. That should solve my problem with the nested one. So, that's my question: I have a ListView with a custom panel If I return a measurement width on the panel and the ListView is resized to less than that width, it stops calling MeasureOverride How can I get it to continue calling MeasureOverride?

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• Complicated MySQL query?

  - by Scott

  I have two tables: RatingsTable that contains a ratingname and a bit whether it is a positive or negative rating: Good 1 Bad 0 Fun 1 Boring 0 FeedbackTable that contains feedback on things...the person rating, the rating and the thing rated. The feedback can be determined if it's a positive or negative rating based on RatingsTable. Jim Chicken Good Jim Steak Bad Ted Waterskiing Fun Ted Hiking Fun Nancy Hiking Boring I am trying to write an efficient MySQL query for the following: On a page, I want to display the the top 'things' that have the highest proportional positive ratings. I want to be sure that the items from the feedback table are unique...meaning, that if Jim has rated Chicken Good 20 times...it should only be counted once. At some point I will want to require a minimum number of ratings (at least 10) to be counted for this page as well. I'll want to to do the same for highest proportional negative ratings, but I am sure I can tweak the one for positive accordingly.

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• gethostbyname in C

  - by Matic

  I don't know how to write applications in C, but I need a tiny program that does: lh = gethostbyname("localhost"); output = lh->h_name; output variable is to be printed. The above code is used in PHP MongoDB database driver to get the hostname of the computer (hostname is part of an input to generate an unique ID). I'm skeptical that this will return the hostname, so I'd like some proof. Any code examples would be most helpful. Happy day, Matic

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• [C#] How to consume web service adheres to the Event-based Asynchronous Pattern?

  - by codemonkie

  I am following the example from http://msdn.microsoft.com/en-us/library/8wy069k1.aspx to consume a web service implemented (by 3rd party) using the Event-based Asynchronous Pattern. However, my program needs to do multiple calls to the DoStuffAsync() hence will get back as many DoStuffCompleted. I chose the overload which takes an extra parameter - Object userState to distinguish them. My first question is: Is it valid to cast a GUID to Object as below, where GUID is used to generate unique taskID? Object userState = Guid.NewGuid(); Secondly, do I need to spawn off a new thread for each DoStuffAsync() call, since I am calling it multiple times? Also, would be nice to have some online examples or tutorials on this subject. (I've been googling for it the whole day and didn't get much back) Many thanks

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• Simulating a belongs_to_many in rails

  - by DavidP6

  I have a situation where in theory I would need to use a belongs_to_many relationship. I have an Example model and a Sentence model. Each example object has one sentence but these sentences are not necessarily unique. So, for example, I could have two example models that each have one sentence that is the same sentence. I'm not sure how to go about doing this in rails. I tried using has_and_belongs_to_many, but ran into problems. It seems that I only need the belongs_to :many part of that relationship. Ideally it would look something like this, but I know there is no belongs_to :many. Example has_one :sentence end Sentence belongs_to_many :examples end

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• How to perform COUNT() or COUNT(*)

  - by ninumedia

  I have a list of tags in a database. Ex: villan hero spiderman superman superman I wanted to obtain a sorted list of the tag names in ascending order and the number of times the unique tag appeared in the database. I wrote this code: Ex: SELECT hashtag.tag_name, COUNT( * ) AS number FROM hashtag GROUP BY hashtag.tag_name ORDER BY hashtag.tag_name ASC This yields the correct result: hero - 1 spiderman - 1 superman - 2 villan - 1 How can I obtain the full COUNT of this entire list. The answer should be 4 in this case because there are naturally 4 rows. I can't seem to get a correct COUNT() without the statement failing. Thanks so much for the help! :)

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• Checking instance of non-class constrained type parameter for null in generic method

  - by casperOne

  I currently have a generic method where I want to do some validation on the parameters before working on them. Specifically, if the instance of the type parameter T is a reference type, I want to check to see if it's null and throw an ArgumentNullException if it's null. Something along the lines of: // This can be a method on a generic class, it does not matter. public void DoSomething<T>(T instance) { if (instance == null) throw new ArgumentNullException("instance"); Note, I do not wish to constrain my type parameter using the class constraint. I thought I could use Marc Gravell's answer on "How do I compare a generic type to its default value?", and use the EqualityComparer<T> class like so: static void DoSomething<T>(T instance) { if (EqualityComparer<T>.Default.Equals(instance, null)) throw new ArgumentNullException("instance"); But it gives a very ambiguous error on the call to Equals: Member 'object.Equals(object, object)' cannot be accessed with an instance reference; qualify it with a type name instead How can I check an instance of T against null when T is not constrained on being a value or reference type?

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