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• How to show percentage of 'memory used' in a win32 process?

  - by pj4533

  I know that memory usage is a very complex issue on Windows. I am trying to write a UI control for a large application that shows a 'percentage of memory used' number, in order to give the user an indication that it may be time to clear up some memory, or more likely restart the application. One implementation used ullAvailVirtual from MEMORYSTATUSEX as a base, then used HeapWalk() to walk the process heap looking for additional free memory. The HeapWalk() step was needed because we noticed that after a while of running the memory allocated and freed by the heap was never returned and reported by the ullAvailVirtual number. After hours of intensive working, the ullAvailVirtual number no longer would accurately report the amount of memory available. However, this method proved not ideal, due to occasional odd errors that HeapWalk() would return, even when the process heap was not corrupted. Further, since this is a UI control, the heap walking code was executing every 5-10 seconds. I tried contacting Microsoft about why HeapWalk() was failing, escalated a case via MSDN, but never got an answer other than "you probably shouldn't do that". So, as a second implementation, I used PagefileUsage from PROCESS_MEMORY_COUNTERS as a base. Then I used VirtualQueryEx to walk the virtual address space adding up all regions that weren't MEM_FREE and returned a value for GetMappedFileNameA(). My thinking was that the PageFileUsage was essentially 'private bytes' so if I added to that value the total size of the DLLs my process was using, it would be a good approximation of the amount of memory my process was using. This second method seems to (sorta) work, at least it doesn't cause crashes like the heap walker method. However, when both methods are enabled, the values are not the same. So one of the methods is wrong. So, StackOverflow world...how would you implement this? which method is more promising, or do you have a third, better method? should I go back to the original method, and further debug the odd errors? should I stay away from walking the heap every 5-10 seconds? Keep in mind the whole point is to indicate to the user that it is getting 'dangerous', and they should either free up memory or restart the application. Perhaps a 'percentage used' isn't the best solution to this problem? What is? Another idea I had was a color based system (red, yellow, green, which I could base on more factors than just a single number)

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• Exception opening TAdoDataset: Arguments are of the wrong type, are out of acceptable range, or are

  - by Dave Falkner

  I've been trying to debug the following problem for several weeks now - this method is called from several places within the same datamodule, but this exception (from the subject line of this post) only occurs when integers for a certain purpose (pickup orders vs. orders that we ship through a carrier) are used - and don't ask me how the application can tell the difference between one integer's purpose and another! Furthermore, I cannot duplicate this issue on my machine - the error occurs on a warehouse machine but not my own development machine, even when working with the same production database. I have suspected an MDAC version conflict between the two machines, but have run a version checker and confirmed that both machines are running 2.8, and additionally have confirmed this by logging the TAdoDataset's .Version property at runtime. function TdmESShip.SecondaryID(const PrimaryID : Integer ): String; begin try with qESPackage2 do begin if Active then Close; LogMessage('-----------------------------------'); LogMessage('Version: ' + FConnection.Version); LogMessage('DB Info: ' + FConnection.Properties['Initial Catalog'].Value + ' ' + FConnection.Properties['Data Source'].Value); LogMessage('Setting the parameter.'); Parameters.ParamByName('ParameterName').Value := PrimaryID; LogMessage('Done setting the parameter.'); Open; Ninety-nine times out of 100 this logging code logs a successful operation as follows: Version: 2.8 DB Info: (database name and instance) Setting the parameter. Done setting the parameter. Opened the dataset. But then whenever a "pickup" order is processed, this exception gets thrown whenever the dataset is opened: Version: 2.8 DB Info: (database name and instance) Setting the parameter. Done setting the parameter. GetESPackageID() threw an exception. Type: EOleException, Message: Arguments are of the wrong type, are out of acceptable range, or are in conflict with one another Error: Arguments are of the wrong type, are out of acceptable range, or are in conflict with one another for packageID 10813711 I've tried eliminating the parameter and have built the commandtext for this dataset programmatically, suspecting that some part of the TParameter's configuration might be out of whack, but the same error occurs under the same circumstances. I've tried every combination of TParameter properties that I can think of - this is the millionth TParameter I've created for my millionth dataset, and I've never encountered this error. I've even created a second dataset from scratch and removed all references to the original dataset in case some property of the original dataset in the .dfm might be corrupted, but the same error occurs under the same circumstances. The commandtext for this dataset is a simple select ValueA from TableName where ValueB = @ParameterB I'm about ready to do something extreme, such as writing a web service to look these values up - it feels right now as though I could destroy my machine, rebuild it, rewrite this entire application from scratch, and the application would still know to throw an exception whenever I try to look up a secondary value from a primary value, but only for pickup orders, and only from the one machine in the warehouse, but I'm probably missing something simple. So, any help anyone could provide would be greatly appreciated.

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• Call asp.net web service from php

  - by SamB09

  Hi im calling an aps.net web service from a php service. The service searches both databases with a search parameter. Im not sure how to pass a search parameter to the asp.net service. Code is below. ( there is no search paramter currently but im just interested in how it would be passed to the asp.net service) $link = mysql_connect($host, $user, $passwd); mysql_select_db($dbName); $query = 'SELECT firstname, surname, phone, location FROM staff ORDER BY surname'; $result = mysql_query($query,$link); // if there is a result if ( mysql_num_rows($result) > 0 ) { // set up a DOM object $xmlDom1 = new DOMDocument(); $xmlDom1->appendChild($xmlDom1->createElement('directory')); $xmlRoot = $xmlDom1->documentElement; // loop over the rows in the result while ( $row = mysql_fetch_row($result) ) { $xmlPerson = $xmlDom1->createElement('staff'); $xmlFname = $xmlDom1->createElement('fname'); $xmlText = $xmlDom1->createTextNode($row[0]); $xmlFname->appendChild($xmlText); $xmlPerson->appendChild($xmlFname); $xmlSname = $xmlDom1->createElement('sname'); $xmlText = $xmlDom1->createTextNode($row[1]); $xmlSname->appendChild($xmlText); $xmlPerson->appendChild($xmlSname); $xmlTel = $xmlDom1->createElement('phone'); $xmlText = $xmlDom1->createTextNode($row[2]); $xmlTel->appendChild($xmlText); $xmlPerson->appendChild($xmlTel); $xmlLoc = $xmlDom1->createElement('loc'); $xmlText = $xmlDom1->createTextNode($row[3]); $xmlLoc->appendChild($xmlText); $xmlPerson->appendChild($xmlLoc); $xmlRoot->appendChild($xmlPerson); } } // // instance a SOAP client to the dotnet web service and read it into a DOM object // (this really should have an exception handler) // $client = new SoapClient('http://stuiis.cms.gre.ac.uk/mk05/dotnet/dataBind01/phoneBook.asmx?WSDL'); $xmlString = $client->getDirectoryDom()->getDirectoryDomResult->any; $xmlDom2 = new DOMDocument(); $xmlDom2->loadXML($xmlString); // merge the second DOM object into the first foreach ( $xmlDom2->documentElement->childNodes as $staffNode ) { $xmlPerson = $xmlDom1->createElement($staffNode->nodeName); foreach ( $staffNode->childNodes as $xmlNode ) { $xmlElement = $xmlDom1->createElement($xmlNode->nodeName); $xmlText = $xmlDom1->createTextNode($xmlNode->nodeValue); $xmlElement->appendChild($xmlText); $xmlPerson->appendChild($xmlElement); } $xmlRoot->appendChild($xmlPerson); } // return result echo $xmlDom

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• Appending data into Listview control

  - by strakastroukas

  In my webpage i use the following in order filling the listview control <asp:ListView ID="ListView1" runat="server"> <layouttemplate> <asp:PlaceHolder id="itemPlaceholder" runat="server" /></layouttemplate> <ItemTemplate> <tr> <td><asp:Label ID="Label1" runat="server" Text = '<%# DataBinder.Eval(Container.DataItem, "Ans1") %>' Visible = '<%# DataBinder.Eval(Container.DataItem, "Ans1Visible") %>'></asp:Label> <br /> <asp:Label ID="Label2" runat="server" Text = '<%# DataBinder.Eval(Container.DataItem, "Ans2") %>' Visible = '<%# DataBinder.Eval(Container.DataItem, "Ans2Visible") %>'></asp:Label> <br /> <asp:Label ID="Label3" runat="server" Text = '<%# DataBinder.Eval(Container.DataItem, "Ans3") %>' Visible = '<%# DataBinder.Eval(Container.DataItem, "Ans3Visible") %>'></asp:Label> <br /> <asp:Label ID="Label4" runat="server" Text = '<%# DataBinder.Eval(Container.DataItem, "Ans4") %>' Visible = '<%# DataBinder.Eval(Container.DataItem, "Ans4Visible") %>'></asp:Label> <br /> <asp:Label ID="Label5" runat="server" Text = '<%# DataBinder.Eval(Container.DataItem, "Ans5") %>' Visible = '<%# DataBinder.Eval(Container.DataItem, "Ans5Visible") %>'></asp:Label> <br /> <asp:Label ID="Label6" runat="server" Text = '<%# DataBinder.Eval(Container.DataItem, "Ans6") %>' Visible = '<%# DataBinder.Eval(Container.DataItem, "Ans6Visible") %>'></asp:Label> </td> </tr> </ItemTemplate> </asp:ListView> Now i would like to add numbers to the labels before they are rendered. For example currently the data displayed are like Tennis Football Basketball Nfl Nba Polo and the output i would like to have is 1. Tennis 2. Football 3. Basketball 4. Nfl 5. Nba 6. Polo Could i use ListView1_ItemCreated or the ListView1_ItemDataBound event to achieve this? If that is true, could you point me a place to start?

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• Contact Bubble EditText

  - by toobsco42

  I am trying to create contact bubbles in the MultiAutoCompleteTextView similiar to how it is implemented in the Google+ app. Below is a screen shot: . I have tried to extend the DynamicDrawableSpan class in order to get a spannable drawable in the background of a span of text public class BubbleSpan extends DynamicDrawableSpan { private Context c; public BubbleSpan(Context context) { super(); c = context; } @Override public Drawable getDrawable() { Resources res = c.getResources(); Drawable d = res.getDrawable(R.drawable.oval); d.setBounds(0, 0, 100, 20); return d; } } Where my oval.xml drawable is defined as so: <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval"> <solid android:color="#00000000"/> <stroke android:width="4dp" android:color="#99000000" android:dashWidth="4dp" android:dashGap="2dp" /> <padding android:left="7dp" android:top="7dp" android:right="7dp" android:bottom="7dp" /> <corners android:radius="4dp" /> </shape> In my Activity class that has the MulitAutoCompleteTextView, I set the bubble span like so: final Editable e = tv.getEditableText(); final SpannableStringBuilder sb = new SpannableStringBuilder(); sb.append("some sample text"); sb.setSpan(new BubbleSpan(getApplicationContext()), 0, 6, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE); e.append(sb); However, instead of the oval shape displaying behind the first 6 characters in the string, the characters are not visible and there is no oval drawable in the background. If i change the BubbleSpan's getDrawable() method to use a .png instead of a shape drawable: public Drawable getDrawable() { Resources res = c.getResources(); Drawable d = res.getDrawable(android.R.drawable.bottom_bar); d.setBounds(0, 0, 100, 20); return d; } Then the .png will show up but the characters in the string that are a part of the span will not show up. How can I make it so that the characters in the span are displayed in the foreground, meanwhile a custom shape drawable gets displayed in the background? I attempted to also use an ImageSpan instead of subclassing DynamicDrawableSpan but was unsuccessful.

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• Using multiple aggregate functions in an algebraic expression in (ANSI) SQL statement

  - by morpheous

  I have the following aggregate functions (AGG FUNCs): foo(), foobar(), fredstats(), barneystats(). I want to know if I can use multiple AGG FUNCs in an algebraic expression. This may seem a strange/simplistic question for seasoned SQL developers - however, the but the reason I ask is that so far, all AGG FUNCs examples I have seen are of the simplistic variety e.g. max(salary) < 100, rather than using the AGG FUNCs in an expression which involves using multiple AGG FUNCs in an expression (like agg_func1() agg_func2()). The information below should help clarify further. Given tables with the following schemas: CREATE TABLE item (id int, length float, weight float); CREATE TABLE item_info (item_id, name varchar(32)); # Is it legal (ANSI) SQL to write queries of this format ? SELECT id, name, foo, foobar, fredstats FROM A, B (SELECT id, foo(123) as foo, foobar('red') as foobar, fredstats('weight') as fredstats FROM item GROUP BY id HAVING [ALGEBRAIC EXPRESSION] ORDER BY id AS A), item_info AS B WHERE item.id = B.id Where: ALGEBRAIC EXPRESSION is the type of expression that can be used in a WHERE clause - for example: ((foo(x) < foobar(y)) AND foobar(y) IN (1,2,3)) OR (fredstats(x) <> 0)) I am using PostgreSQL as the db, but I would prefer to use ANSI SQL wherever possible. Assuming it is legal to include AGG FUNCS in the way I have done above, I'd like to know: Is there a more efficient way to write the above query ? Is there any way I can speed up the query in terms of a judicious choice of indexes on the tables item and item_info ? Is there a performance hit of using AGG FUNCs in an algebraic expression like I am (i.e. an expression involving the output of aggregate functions rather than constants? Can the expression also include 'scaled' AGG FUNC? (for example: 2*foo(123) < -3*foobar(456) ) - will scaling (i.e. multiplying an AGG FUNC by a number have an effect on performance?) How can I write the query above using INNER JOINS instead?

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• can we use both custom button and inbuilt button in datagridview

  - by Srikanth Mattihalli

  HI all, I am using Datagridview in asp.net. I have used custom buttons of up and down in the datagridview along with edit,delete and paging options. I am handling the up down buttons by raising events in rowcommand and the code is as below string command = e.CommandName; Response.Write(e.CommandArgument.ToString()); int index = Convert.ToInt32(e.CommandArgument.ToString()); int count = GridView1.Rows.Count; int keyValue = Convert.ToInt32(GridView1.Rows[index].Cells1.Text); string value = GridView1.Rows[index].Cells[4].Text; SqlConnection conn = new SqlConnection(SqlDataSource1.ConnectionString); SqlCommand cmd = new SqlCommand(); if (command == "up") { if (index > 0) { index = index - 1; int keyValue1 = Convert.ToInt32(GridView1.Rows[index].Cells[1].Text); string value1 = GridView1.Rows[index].Cells[4].Text; cmd.Connection = conn; cmd.CommandText = "UPDATE [category] SET [order_id] = '" + value + "' WHERE [category_id]=" + keyValue1 + ";UPDATE [category] SET [order_id] = '" + value1 + "' WHERE [category_id]=" + keyValue + ";"; conn.Open(); cmd.ExecuteNonQuery(); conn.Close(); } } else if (command == "down") { if (index < count - 1) { index = index + 1; int keyValue1 = Convert.ToInt32(GridView1.Rows[index].Cells[1].Text); string value1 = GridView1.Rows[index].Cells[4].Text; cmd.Connection = conn; cmd.CommandText = "UPDATE [category] SET [order_id] = '" + value + "' WHERE [category_id]=" + keyValue1 + ";UPDATE [category] SET [order_id] = '" + value1 + "' WHERE [category_id]=" + keyValue + ";"; conn.Open(); cmd.ExecuteNonQuery(); conn.Close(); } } Response.Redirect("Default.aspx"); Designer file " DeleteCommand="DELETE FROM [category] WHERE [category_id] = @category_id" InsertCommand="INSERT INTO [category] ([categoryname], [navigation_url], [order_id]) VALUES (@categoryname, @navigation_url, @order_id)" SelectCommand="SELECT * FROM [category] order by order_id" UpdateCommand="UPDATE [category] SET [categoryname] = @categoryname, [navigation_url] = @navigation_url, [order_id] = @order_id WHERE [category_id] = @category_id" After this my edit,delete and paging is not working bcoz of event conflicts. Can anyone plz help me on this, so that i will be able to use both custom buttons(up and down) and edit,delete and paging features.

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• Java map / nio / NFS issue causing a VM fault: "a fault occurred in a recent unsafe memory access op

  - by Matthew Bloch

  I have written a parser class for a particular binary format (nfdump if anyone is interested) which uses java.nio's MappedByteBuffer to read through files of a few GB each. The binary format is just a series of headers and mostly fixed-size binary records, which are fed out to the called by calling nextRecord(), which pushes on the state machine, returning null when it's done. It performs well. It works on a development machine. On my production host, it can run for a few minutes or hours, but always seems to throw "java.lang.InternalError: a fault occurred in a recent unsafe memory access operation in compiled Java code", fingering one of the Map.getInt, getShort methods, i.e. a read operation in the map. The uncontroversial (?) code that sets up the map is this: /** Set up the map from the given filename and position */ protected void open() throws IOException { // Set up buffer, is this all the flexibility we'll need? channel = new FileInputStream(file).getChannel(); MappedByteBuffer map1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size()); map1.load(); // we want the whole thing, plus seems to reduce frequency of crashes? map = map1; // assumes the host writing the files is little-endian (x86), ought to be configurable map.order(java.nio.ByteOrder.LITTLE_ENDIAN); map.position(position); } and then I use the various map.get* methods to read shorts, ints, longs and other sequences of bytes, before hitting the end of the file and closing the map. I've never seen the exception thrown on my development host. But the significant point of difference between my production host and development is that on the former, I am reading sequences of these files over NFS (probably 6-8TB eventually, still growing). On my dev machine, I have a smaller selection of these files locally (60GB), but when it blows up on the production host it's usually well before it gets to 60GB of data. Both machines are running java 1.6.0_20-b02, though the production host is running Debian/lenny, the dev host is Ubuntu/karmic. I'm not convinced that will make any difference. Both machines have 16GB RAM, and are running with the same java heap settings. I take the view that if there is a bug in my code, there is enough of a bug in the JVM not to throw me a proper exception! But I think it is just a particular JVM implementation bug due to interactions between NFS and mmap, possibly a recurrence of 6244515 which is officially fixed. I already tried adding in a "load" call to force the MappedByteBuffer to load its contents into RAM - this seemed to delay the error in the one test run I've done, but not prevent it. Or it could be coincidence that was the longest it had gone before crashing! If you've read this far and have done this kind of thing with java.nio before, what would your instinct be? Right now mine is to rewrite it without nio :)

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• What Can I Do To One Of My Team Number (Good Friend As Well) Who Lost His Passion.

  - by skyflyer

  It seems this question is not program related, but there are lot of similar questions. So please bear with me! By the way, I am programmer and my team is also charging a software project. And SO is the only place which solved me lot of thorny troubles!THANK YOU GUYS! I joined my company with him years ago. At that time he was quite passionate on his job which is a front-end development. He gave us lot of useful suggestions concerning his work like design. And I believed he was a smart guy. I believe he still is smart too by the way. One years later, however, he seemed lost his passion and fooling around every day, did not care about his work any more and produced poorwork. Even worse he literally stopped learning new skills and honing his work related skills. For me it is horrible, we got to keep abreast with new technology development, otherwise we will be throw out. Since we were just coworkers, I did not care about it too much except mentioned my thoughts several times. But last month, we resembled a new group and assigned very important project. And I am the team leader, sadly! My boss gave me lot of support and expectation as well. I did a pretty good job before and I am very optimism to our future. But as a team, if my team does not work hard, we will be doomed to failure no matter how hard I work and push. In order to revitalize his passion, I tried couple of ways like talking to him about my concern and my boss's angry. I offered his new task which is quite new to him. I even persuaded my boss to give him new incentive package. But all of them knocked wall. His reaction was just he did not care. Even worse he did not want to talk about his situation. I want to be hard on him, but since we are friends and coworkers, I really can not see it will work. Even it works, I can not so quickly change my self from friend and coworker into manager. As a novice in management, I am really overwhelmed! I do not want get him fired, we are friends and I do not see him fired as my team number. What can I do? Thank you guys!

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• How can I refactor out needing so many for-loops in rails?

  - by Angela

  I need help refactoring this multi-loop thing. Here is what I have: Campaign has_many Contacts Campaign also has many templates for EVent (Email, Call, and Letter). I need a list of all the Emails, Calls and Letters that are "overdue" for every Contact that belongs to a Campaign. Overdue is determined by a from_today method which looks at the date the Contact was entered in the system and the number of days that needs to pass for any given Event. from_today() outputs the number of days from today that the Event should be done for a given Contact. Here is what I've done, it works for all Emails in a Campaign across all contacts. I was going to try to create another each do loop to change the class names. Wasn't sure where to begin: named_scope, push some things into a method, etcetera, or -- minimum to be able to dynamically change the class names so at least it loops three timees across the different events rather than repeating the code three times: <% @campaigns.each do |campaign| %> <h2><%= link_to campaign.name, campaign %></h2> <% @events.each do |event| %> <%= event %> <% for email in campaign.emails %> <h4><%= link_to email.title, email %> <%= email.days %> days</h4> <% for contact in campaign.contacts.find(:all, :order => "date_entered ASC" ) %> <% if (from_today(contact, email.days) < 0) %> <% if show_status(contact, email) == 'no status'%> <p> <%= full_name(contact) %> is <%= from_today(contact,email.days).abs%> days overdue: <%= do_event(contact, email) %> </p> <% end %> <% end %> <% end %> <% end %> <% end %> <% end %>

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• Multiplying field value with retreived value jQuery

  - by Efe

  I pull product price from another page. Then I multiply it with quantity entered in the quantity input field. The problem is, if I forget to enter quantity value before I pull product price data or if I change the quantity field later, the final total price is not updated. I hope I clearly explained it. javascript: $('#AddProduct').click(function() { var i = 0; var adding = $(+(i++)+'<div class="row'+(i)+'"><div class="column width50"><input type="text" id="PRODUCTNAME" name="PRODUCTNAME'+(i)+'" value="" class="width98" /><input type="hidden" class="PRODUCTID" name="PRODUCTID" /><input type="hidden" class="UNITPRICE" name="UNITPRICE'+(i)+'" /><small>Search Products</small></div><div class="column width20"><input type="text" class="UNITQUANTITY" name="UNITQUANTITY'+(i)+'" value="" class="width98" /><small>Quantity</small></div><div class="column width30"><span class="prices">Unit Price:<span class="UNITPRICE"></span><br />Total Price:<span class="TOTALPRICE"></span><br /><a href="#" id="RemoveProduct(".row'+(i)+'");">Remove</a></span></div>'); $('#OrderProducts').append(adding); adding.find("#PRODUCTNAME").autocomplete("orders.cs.asp?Process=ListProducts", { selectFirst: false }).result(function(event, data, formatted) { if (data) { adding.find(".UNITPRICE").html(data[1]); adding.find(".PRODUCTID").val(data[2]); adding.find(".TOTALPRICE").html(data[1] * $('.UNITQUANTITY').val()); } }); return false; }); $('#RemoveProduct').click(function() { $().remove(); return false; }); my html: <fieldset> <h2>Order Items</h2> <div id="OrderProducts"> <a href="#" id="AddProduct"><img src="icons/add.png" alt="Add" /></a> </div> </fieldset> edit Now I totaly messed it up. Removing a row is not working anymore as well... Test link: http://refinethetaste.com/html/cp/?Section=orders&Process=AddOrder#

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• Add new row to asp .net grid view using button

  - by SARAVAN

  Hi, I am working in ASP .net 2.0. I am a learner. I have a grid view which has a button in it. Please find the asp mark up below <form id="form1" runat="server"> <div> <asp:GridView ID="myGridView" runat="server"> <Columns> <asp:TemplateField> <ItemTemplate> <asp:Button CommandName="AddARowBelow" Text="Add A Row Below" runat="server" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> </div> </form> Please find the code behind below. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Data; using System.Web.UI.WebControls; namespace GridViewDemo { public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { DataTable dt = new DataTable("myTable"); dt.Columns.Add("col1"); dt.Columns.Add("col2"); dt.Columns.Add("col3"); dt.Rows.Add(1, 2, 3); dt.Rows.Add(1, 2, 3); dt.Rows.Add(1, 2, 3); dt.Rows.Add(1, 2, 3); dt.Rows.Add(1, 2, 3); myGridView.DataSource = dt; myGridView.DataBind(); } protected void myGridView_RowCommand(object sender, GridViewCommandEventArgs e) { } } } I was thinking that when I click the command button, it would fire the mygridview_rowcommand() but instead it threw an error as follows: Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" % in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation. Can any one let me know on where I am going wrong?

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• Read variable-length records from a buffer - weird memory issues

  - by bsg

  Hi, I'm trying to implement an i/o intensive quicksort (C++ qsort) on a very large dataset. In the interests of speed, I'd like to read in a chunk of data at a time into a buffer and then use qsort to sort it inside the buffer. (I am currently working with text files but would like to move to binary soon.) However, my data is composed of variable-length records, and qsort needs to be told the length of the record in order to sort. Is there any way to standardize this? The only thing I could think of was rather convoluted: my program currently reads from the buffer until it hits a linefeed character ('10' in ascii), transferring each character over to another array. When it finds a linefeed (the delimiter in the input file), it fills the number of spaces remaining in the buffer for that record (record size is set to 30) with null characters. This way, I should end up with a buffer full of fixed-size records to give qsort. I know there are several problems with my approach, one being that it's just clumsy, another that the record size might conceivably be larger than 30, but is generally much less. Is there a better way of doing this? As well, my current code doesn't even work. When I debug it, it seems to be transferring characters from one buffer to the other, but when I try to print out the buffer, it contains only the first record. Here is my code: FILE *fp; unsigned char *buff; unsigned char *realbuff; FILE *inputFiles[NUM_INPUT_FILES]; buff = (unsigned char *) malloc(2048); realbuff = (unsigned char *) malloc(NUM_RECORDS * RECORD_SIZE); fp = fopen("postings0.txt", "r"); if(fp) { fread(buff, 1, 2048, fp); /*for(int i=0; i <30; i++) cout << buff[i] <<endl;*/ int y=0; int recordcounter = 0; //cout << buff; for(int i=0;i <100; i++) { if(buff[i] != char(10)) { realbuff[y] = buff[i]; y++; recordcounter++; } else { if(recordcounter < RECORD_SIZE) for(int j=recordcounter; j < RECORD_SIZE;j++) { realbuff[y] = char(0); y++; } recordcounter = 0; } } cout << realbuff <<endl; cout << buff; } else cout << "sorry"; Thank you very much, bsg

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• GAE Datastore: persisting referenced objects

  - by David

  Two "I'm sorries" to begin with: 1) I've looked for a solution (here, and elsewhere), and couldn't find the answer. 2) English is not my mother tongue, so I may have some typos and the sort - please ignore them. To the point: I am trying to persist Java objects to the GAE datastore. I am not sure as to how to persist object having ("non-trivial") referenced object. That is, assume I have the following. public class Father { String name; int age; Vector<Child> offsprings; //this is what I call "non-trivial" reference //ctor, getters, setters... } public class Child { String name; int age; Father father; //this is what I call "non-trivial" reference //ctor, getters, setters... } The name field is unique in each type domain, and is considered a Primary-Key. In order to persist the "trivial" (String, int) fields, all I need is to add the correct annotation. So far so good. However, I don't understand how should I persist the home-brewed (Child, Father) types referenced. Should I: Convert each such reference to hold the Primary-Key (a name String, in this example) instead of the "actual" object. So, Vector<Child> offsprings; becomes Vector<String> offspringsNames; ? If that is the case, how do I handle the object at run-time? Do I just query for the Primary-Key from Class.getName, to retrieve the refrenced objects? Convert each such reference to hold the actual Key provided to me by the Datastore upon the proper put() operation? So, Vector<Child> offsprings; becomes Vector<Key> offspringsHashKeys; ? I would very much appreciate all kinds of comments. I have read ALL the offical relevant GAE docs/example. Throughout, they always persist "trivial" references, natively supported by the Datastore (e.g. in the Guestbook example, only Strings, and Longs). Many thanks, David

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• Algorithm for finding symmetries of a tree

  - by Paxinum

  I have n sectors, enumerated 0 to n-1 counterclockwise. The boundaries between these sectors are infinite branches (n of them). The sectors live in the complex plane, and for n even, sector 0 and n/2 are bisected by the real axis, and the sectors are evenly spaced. These branches meet at certain points, called junctions. Each junction is adjacent to a subset of the sectors (at least 3 of them). Specifying the junctions, (in pre-fix order, lets say, starting from junction adjacent to sector 0 and 1), and the distance between the junctions, uniquely describes the tree. Now, given such a representation, how can I see if it is symmetric wrt the real axis? For example, n=6, the tree (0,1,5)(1,2,4,5)(2,3,4) have three junctions on the real line, so it is symmetric wrt the real axis. If the distances between (015) and (1245) is equal to distance from (1245) to (234), this is also symmetric wrt the imaginary axis. The tree (0,1,5)(1,2,5)(2,4,5)(2,3,4) have 4 junctions, and this is never symmetric wrt either imaginary or real axis, but it has 180 degrees rotation symmetry if the distance between the first two and the last two junctions in the representation are equal. Edit: This is actually for my research. I have posted the question at mathoverflow as well, but my days in competition programming tells me that this is more like an IOI task. Code in mathematica would be excellent, but java, python, or any other language readable by a human suffices. Here are some examples (pretend the double edges are single and we have a tree) http://www2.math.su.se/~per/files.php?file=contr_ex_1.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_2.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_5.pdf Example 1 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,3). Example 2 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,1). Example 5 is described as (0,1,4,5)(1,2,3,4) with distances (2). So, given the description/representation, I want to find some algorithm to decide if it is symmetric wrt real, imaginary, and rotation 180 degrees. The last example have 180 degree symmetry. (These symmetries corresponds to special kinds of potential in the Schroedinger equation, which has nice properties in quantum mechanics.)

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• Workflow for statistical analysis and report writing

  - by ws

  Does anyone have any wisdom on workflows for data analysis related to custom report writing? The use-case is basically this: Client commissions a report that uses data analysis, e.g. a population estimate and related maps for a water district. The analyst downloads some data, munges the data and saves the result (e.g. adding a column for population per unit, or subsetting the data based on district boundaries). The analyst analyzes the data created in (2), gets close to her goal, but sees that needs more data and so goes back to (1). Rinse repeat until the tables and graphics meet QA/QC and satisfy the client. Write report incorporating tables and graphics. Next year, the happy client comes back and wants an update. This should be as simple as updating the upstream data by a new download (e.g. get the building permits from the last year), and pressing a "RECALCULATE" button, unless specifications change. At the moment, I just start a directory and ad-hoc it the best I can. I would like a more systematic approach, so I am hoping someone has figured this out... I use a mix of spreadsheets, SQL, ARCGIS, R, and Unix tools. Thanks! PS: Below is a basic Makefile that checks for dependencies on various intermediate datasets (w/ ".RData" suffix) and scripts (".R" suffix). Make uses timestamps to check dependencies, so if you 'touch ss07por.csv', it will see that this file is newer than all the files / targets that depend on it, and execute the given scripts in order to update them accordingly. This is still a work in progress, including a step for putting into SQL database, and a step for a templating language like sweave. Note that Make relies on tabs in its syntax, so read the manual before cutting and pasting. Enjoy and give feedback! http://www.gnu.org/software/make/manual/html%5Fnode/index.html#Top R=/home/wsprague/R-2.9.2/bin/R persondata.RData : ImportData.R ../../DATA/ss07por.csv Functions.R $R --slave -f ImportData.R persondata.Munged.RData : MungeData.R persondata.RData Functions.R $R --slave -f MungeData.R report.txt: TabulateAndGraph.R persondata.Munged.RData Functions.R $R --slave -f TabulateAndGraph.R report.txt

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• Unrequired property keeps getting data-val-required attribute

  - by frennky

  This is the model with it's validation: [MetadataType(typeof(TagValidation))] public partial class Tag { } public class TagValidation { [Editable(false)] [HiddenInput(DisplayValue = false)] public int TagId { get; set; } [Required] [StringLength(20)] [DataType(DataType.Text)] public string Name { get; set; } //... } Here is the view: <h2>Create</h2> <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script> @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>Tag</legend> <div>@Html.EditorForModel()</div> <p> <input type="submit" value="Create" /> </p> </fieldset> } <div> @Html.ActionLink("Back to List", "Index") </div> And here is what get's renderd: <form action="/Tag/Create" method="post"> <fieldset> <legend>Tag</legend> <div><input data-val="true" data-val-number="The field TagId must be a number." data-val-required="The TagId field is required." id="TagId" name="TagId" type="hidden" value="" /> <div class="editor-label"><label for="Name">Name</label></div> <div class="editor-field"><input class="text-box single-line" data-val="true" data-val-length="The field Name must be a string with a maximum length of 20." data-val-length-max="20" data-val-required="The Name field is required." id="Name" name="Name" type="text" value="" /> <span class="field-validation-valid" data-valmsg-for="Name" data-valmsg-replace="true"></span></div> ... </fieldset> </form> The problem is that TagId validation gets generated althoug thare is no Required attribute set on TagId property. Because of that I can't even pass the client-side validation in order to create new Tag in db. What am I missing?

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• CSS3's border-radius property and border-collapse:collapse don't mix. How can I use border-radius to

  - by vamin

  Edit - Original Title: Is there an alternative way to achieve border-collapse:collapse in CSS (in order to have a collapsed, rounded corner table)? Since it turns out that simply getting the table's borders to collapse does not solve the root problem, I have updated the title to better reflect the discussion. I am trying to make a table with rounded corners using the CSS3 border-radius property. The table styles I'm using look something like this: table { -moz-border-radius:10px; -webkit-border-radius:10px; border-radius:10px} Here's the problem. I also want to set the border-collapse:collapse property, and when that is set border-radius no longer works (at least in Firefox)(edit- I thought this might just be a difference in mozilla's implementation, but it turns out this is the way it's supposed to work according to the w3c). Is there a CSS-based way I can get the same effect as border-collapse:collapse without actually using it? Edits: I've made a simple page to demonstrate the problem here (Firefox/Safari only). It seems that a large part of the problem is that setting the table to have rounded corners does not affect the corners of the corner td elements. If the table was all one color, this wouldn't be a problem since I could just make the top and bottom td corners rounded for the first and last row respectively. However, I am using different background colors for the table to differentiate the headings and for striping, so the inner td elements would show their rounded corners as well. Summary of proposed solutions: Surrounding the table with another element with round corners doesn't work because the table's square corners "bleed through." Specifying border width to 0 doesn't collapse the table. Bottom td corners still square after setting cellspacing to zero. Using javascript instead- works by avoiding the problem. Possible solutions: The tables are generated in php, so I could just apply a different class to each of the outer th/tds and style each corner separately. I'd rather not do this, since it's not very elegant and a bit of a pain to apply to multiple tables, so please keep suggestions coming. Possible solution 2 is to use javascript (jQuery, specifically) to style the corners. This solution also works, but still not quite what I'm looking for (I know I'm picky). I have two reservations: 1) this is a very lightweight site, and I'd like to keep javascript to the barest minimum 2) part of the appeal that using border-radius has for me is graceful degradation and progressive enhancement. By using border-radius for all rounded corners, I hope to have a consistently rounded site in CSS3-capable browsers and a consistently square site in others (I'm looking at you, IE). I know that trying to do this with CSS3 today may seem needless, but I have my reasons. I would also like to point out that this problem is a result of the w3c speficication, not poor CSS3 support, so any solution will still be relevant and useful when CSS3 has more widespread support.

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• PHP 5.2 Function needed for GENERIC sorting of a recordset array

  - by donbriggs

  Somebody must have come up with a solution for this by now. We are using PHP 5.2. (Don't ask me why.) I wrote a PHP class to display a recordset as an HTML table/datagrid, and I wish to expand it so that we can sort the datagrid by whichever column the user selects. In the below example data, we may need to sort the recordset array by Name, Shirt, Assign, or Age fields. I will take care of the display part, I just need help with sorting the data array. As usual, I query a database to get a result, iterate throught he result, and put the records into an assciateiave array. So, we end up with an array of arrays. (See below.) I need to be able to sort by any column in the dataset. However, I will not know the column names at design time, nor will I know if the colums will be string or numeric values. I have seen a ton of solutions to this, but I have not seen a GOOD and GENERIC solution Can somebody please suggest a way that I can sort the recordset array that is GENERIC, and will work on any recordset? Again, I will not know the fields names or datatypes at design time. The array presented below is ONLY an example. UPDATE: Yes, I would love to have the database do the sorting, but that is just not going to happen. The queries that we are running are very complex. (I am not really querying a table of Star Trek characters.) They include joins, limits, and complex WHERE clauses. Writing a function to pick apart the SQL statement to add an ORDER BY is really not an option. Besides, sometimes we already have the array that is a result of the query, rather than the ability to run a new query. Array ( [0] => Array ( [name] => Kirk [shrit] => Gold [assign] => Bridge ) [1] => Array ( [name] => Spock [shrit] => Blue [assign] => Bridge ) [2] => Array ( [name] => Uhura [shrit] => Red [assign] => Bridge ) [3] => Array ( [name] => Scotty [shrit] => Red [assign] => Engineering ) [4] => Array ( [name] => McCoy [shrit] => Blue [assign] => Sick Bay ) )

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• How do I change a child's parent in NHibernate when cascade is delete-all-orphan?

  - by Daniel T.

  I have two entities in a bi-directional one-to-many relationship: public class Storage { public IList<Box> Boxes { get; set; } } public class Box { public Storage CurrentStorage { get; set; } } And the mapping: <class name="Storage"> <bag name="Boxes" cascade="all-delete-orphan" inverse="true"> <key column="Storage_Id" /> <one-to-many class="Box" /> </bag> </class> <class name="Box"> <many-to-one name="CurrentStorage" column="Storage_Id" /> </class> A Storage can have many Boxes, but a Box can only belong to one Storage. I have them mapped so that the one-to-many has a cascade of all-delete-orphan. My problem arises when I try to change a Box's Storage. Assuming I already ran this code: var storage1 = new Storage(); var storage2 = new Storage(); storage1.Boxes.Add(new Box()); Session.Create(storage1); Session.Create(storage2); The following code will give me an exception: // get the first and only box in the DB var existingBox = Database.GetBox().First(); // remove the box from storage1 existingBox.CurrentStorage.Boxes.Remove(existingBox); // add the box to storage2 after it's been removed from storage1 var storage2 = Database.GetStorage().Second(); storage2.Boxes.Add(existingBox); Session.Flush(); // commit changes to DB I get the following exception: NHibernate.ObjectDeletedException : deleted object would be re-saved by cascade (remove deleted object from associations) This exception occurs because I have the cascade set to all-delete-orphan. The first Storage detected that I removed the Box from its collection and marks it for deletion. However, when I added it to the second Storage (in the same session), it attempts to save the box again and the ObjectDeletedException is thrown. My question is, how do I get the Box to change its parent Storage without encountering this exception? I know one possible solution is to change the cascade to just all, but then I lose the ability to have NHibernate automatically delete a Box by simply removing it from a Storage and not re-associating it with another one. Or is this the only way to do it and I have to manually call Session.Delete on the box in order to remove it?

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• Is READ UNCOMMITTED / NOLOCK safe in this situation?

  - by Ben Challenor

  I know that snapshot isolation would fix this problem, but I'm wondering if NOLOCK is safe in this specific case so that I can avoid the overhead. I have a table that looks something like this: drop table Data create table Data ( Id BIGINT NOT NULL, Date BIGINT NOT NULL, Value BIGINT, constraint Cx primary key (Date, Id) ) create nonclustered index Ix on Data (Id, Date) There are no updates to the table, ever. Deletes can occur but they should never contend with the SELECT because they affect the other, older end of the table. Inserts are regular and page splits to the (Id, Date) index are extremely common. I have a deadlock situation between a standard INSERT and a SELECT that looks like this: select top 1 Date, Value from Data where Id = @p0 order by Date desc because the INSERT acquires a lock on Cx (Date, Id; Value) and then Ix (Id, Date), but the SELECT acquires a lock on Ix (Id, Date) and then Cx (Date, Id; Value). This is because the SELECT first seeks on Ix and then joins to a seek on Cx. Swapping the clustered and non-clustered index would break this cycle, but it is not an acceptable solution because it would introduce cycles with other (more complex) SELECTs. If I add NOLOCK to the SELECT, can it go wrong in this case? Can it return: More than one row, even though I asked for TOP 1? No rows, even though one exists and has been committed? Worst of all, a row that doesn't satisfy the WHERE clause? I've done a lot of reading about this online, but the only reproductions of over- or under-count anomalies I've seen (one, two) involve a scan. This involves only seeks. Jeff Atwood has a post about using NOLOCK that generated a good discussion. I was particularly interested in a comment by Rick Townsend: Secondly, if you read dirty data, the risk you run is of reading the entirely wrong row. For example, if your select reads an index to find your row, then the update changes the location of the rows (e.g.: due to a page split or an update to the clustered index), when your select goes to read the actual data row, it's either no longer there, or a different row altogether! Is this possible with inserts only, and no updates? If so, then I guess even my seeks on an insert-only table could be dangerous. Update: I'm trying to figure out how snapshot isolation works. It seems to be row-based, where transactions read the table (with no shared lock!), find the row they are interested in, and then see if they need to get an old version of the row from the version store in tempdb. But in my case, no row will have more than one version, so the version store seems rather pointless. And if the row was found with no shared lock, how is it different to just using NOLOCK?

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• How to successfully implement og:image for the LinkedIn

  - by Sabo

  THE PROBLEM: I am trying, without much success, to implement open graph image on site: http://www.guarenty-group.com/cz/ The homepage is completeply bypassing the og:image tag, where internal pages are reading all images from the site and place og:image as the last option. Other social networks are working fine on both internal pages and homepage. THE CONFIGURATION: I have no share buttons or alike, all I want is to be able to share the link via my profile. The image is well over 300x300px: http://guarenty-group.com/img/gg_seal.png Here is how my head tag looks like: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Guarenty Group : Pojištení pro nájemce a pronajímatelé</title> <meta name="keywords" content="" /> <meta name="description" content="Guarenty Group pojištuje príjem z nájmu pronajímatelum, kauci nájemcum - aby nemuseli platit velkou cástku v hotovostí predem - a dále nájemcum pojištuje príjmy, aby meli na nájem pri nemoci, úrazu ci nezamestnání." /> <meta name="image_src" content="http://guarenty-group.com/img/gg_seal.png" /> <meta name="image_url" content="http://guarenty-group.com/img/gg_seal.png" /> <meta property="og:title" content="Pojištení pro nájemce a pronajímatelé" /> <meta property="og:url" content="http://guarenty-group.com/cz/" /> <meta property="og:image" content="http://guarenty-group.com/img/gg_seal.png" /> <meta property="og:description" content="Guarenty Group pojištuje príjem z nájmu pronajímatelum, kauci nájemcum - aby nemuseli platit velkou cástku v hotovostí predem - a dále nájemcum pojištuje príjmy, aby meli na nájem pri nemoci, úrazu ci nezamestnání [...]" /> ... </head> THE TESTING RESULTS: In order to trick the cache i have tested the site with http://www.guarenty-group.com/cz/?try=N, where I have changed the N every time. The strange thing is that images found for different value of N is different. Sometimes there is no image, sometimes there is 1, 2 or 3 images, but each time there is a different set of images. But, in any case I could not find the image specified in the og:graph! MY QUESTIONS: https://developer.linkedin.com/documents/setting-display-tags-shares is saying one thing, and the personnel on the support forum is saying "over 300" Does anyone know What is the official minimum dimension of the image (both w and h)? Can an image be too large? Should I use the xmlns, should I not use xmlns or it doesn't matter? What are the maximum (and minimum) lengths for og:title and og:description tags? Any other suggestion is of course welcomed :) Thanks in advance, cheers~

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• Validating against a Schema with JAXB

  - by fwgx

  I've been looking for solutions to this problem for far too long considering how easy it sounds so I've come for some help. I have an XML Schema which I have used with xjc to create my JAXB binding. This works fine when the XML is well formed. Unfortunately it also doesn't complain when the XML is not well formed. I cannot figure out how to do proper full validation against the schema when I try to unmarshall an XML file. I have managed to use a ValidationEventCollector to handle events, which works for XML parsing errors such as mismatched tags but doesn't raise any events when there is a tag that is required but is completely absent. From what I have seen validation can be done againsta schema, but you must know the path to the schema in order to pass it into the setSchema() method. The problem I have is that the path to the schema is stored in the XML header and I can't knwo at run time where the schema is going to be. Which is why it's stored in the XML file: <?xml version="1.0" encoding="utf-8"?> <DDSSettings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="/a/big/long/path/to/a/schema/file/DDSSettings.xsd"> <Field1>1</Field1> <Field2>-1</Field2> ...etc Every example I see uses setValidating(true), which is now deprecated, so throws an exception. This is the Java code I have so far, which seems to only do XML validation, not schema validation: try { JAXBContext jc = new JAXBContext() { private final JAXBContext jaxbContext = JAXBContext.newInstance("blah"); @Override public Unmarshaller createUnmarshaller() throws JAXBException { Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); ValidationEventCollector vec = new ValidationEventCollector() { @Override public boolean handleEvent(ValidationEvent event) throws RuntimeException { ValidationEventLocator vel = event.getLocator(); if (event.getSeverity() == event.ERROR || event.getSeverity() == event.FATAL_ERROR) { String error = "XML Validation Exception: " + event.getMessage() + " at row: " + vel.getLineNumber() + " column: " + vel.getColumnNumber(); System.out.println(error); } m_unmarshallingOk = false; return false; } }; unmarshaller.setEventHandler(vec); return unmarshaller; } @Override public Marshaller createMarshaller() throws JAXBException { throw new UnsupportedOperationException("Not supported yet."); } @Override @SuppressWarnings("deprecation") public Validator createValidator() throws JAXBException { throw new UnsupportedOperationException("Not supported yet."); } }; Unmarshaller unmarshaller = jc.createUnmarshaller(); m_ddsSettings = (com.ultra.DDSSettings)unmarshaller.unmarshal(new File(xmlfileName)); } catch (UnmarshalException ex) { Logger.getLogger(UniversalDomainParticipant.class.getName()).log( Level.SEVERE, null, ex); } catch (JAXBException ex) { Logger.getLogger(UniversalDomainParticipant.class.getName()).log( Level.SEVERE, null, ex); } So what is the proper way to do this validation? I was expecting there to be a validate() method on the JAXB generated classes, but I guess that would be too simple for Java.

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• Rails. Putting update logic in your migrations

  - by Daniel Abrahamsson

  A couple of times I've been in the situation where I've wanted to refactor the design of some model and have ended up putting update logic in migrations. However, as far as I've understood, this is not good practice (especially since you are encouraged to use your schema file for deployment, and not your migrations). How do you deal with these kind of problems? To clearify what I mean, say I have a User model. Since I thought there would only be two kinds of users, namely a "normal" user and an administrator, I chose to use a simple boolean field telling whether the user was an adminstrator or not. However, after I while I figured I needed some third kind of user, perhaps a moderator or something similar. In this case I add a UserType model (and the corresponding migration), and a second migration for removing the "admin" flag from the user table. And here comes the problem. In the "add_user_type_to_users" migration I have to map the admin flag value to a user type. Additionally, in order to do this, the user types have to exist, meaning I can not use the seeds file, but rather create the user types in the migration (also considered bad practice). Here comes some fictional code representing the situation: class CreateUserTypes < ActiveRecord::Migration def self.up create_table :user_types do |t| t.string :name, :nil => false, :unique => true end #Create basic types (can not put in seed, because of future migration dependency) UserType.create!(:name => "BASIC") UserType.create!(:name => "MODERATOR") UserType.create!(:name => "ADMINISTRATOR") end def self.down drop_table :user_types end end class AddTypeIdToUsers < ActiveRecord::Migration def self.up add_column :users, :type_id, :integer #Determine type via the admin flag basic = UserType.find_by_name("BASIC") admin = UserType.find_by_name("ADMINISTRATOR") User.all.each {|u| u.update_attribute(:type_id, (u.admin?) ? admin.id : basic.id)} #Remove the admin flag remove_column :users, :admin #Add foreign key execute "alter table users add constraint fk_user_type_id foreign key (type_id) references user_types (id)" end def self.down #Re-add the admin flag add_column :users, :admin, :boolean, :default => false #Reset the admin flag (this is the problematic update code) admin = UserType.find_by_name("ADMINISTRATOR") execute "update users set admin=true where type_id=#{admin.id}" #Remove foreign key constraint execute "alter table users drop foreign key fk_user_type_id" #Drop the type_id column remove_column :users, :type_id end end As you can see there are two problematic parts. First the row creation part in the first model, which is necessary if I would like to run all migrations in a row, then the "update" part in the second migration that maps the "admin" column to the "type_id" column. Any advice?

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• LINQ to XML, a problem conceptualizing how the tree should look.

  - by snark

  Have you ever had one of those days when you've dug a hole but your so deep in now that the only option is to keep on digging and see where you come out? I thought just for giggles in the latest component I'm writing to use LINQ to XML because it was about time I saw what all the hooplah was about. The problem: I am making a graph component that contains series of data that get graphed and then you can apply a formula to that series and graph another series then apply a formula to that series and so on. So I figured that I would do so in 2 steps, create (and manage) an XML representaion of the series and how they relate to each other, then pass this xml to a draw engine which draws. Conceptually its a tree, with the exception of the root all child series being based upon a parent (1 parent can have many children. So I should always be adding child nodes to their parent and if I delete a node(series) then I can simply delete the series and its descendants (then draw) and voila all the messy iterating through each node finding parents and children is unneccessary. Trouble is I dont know how to represent this tree in XML i.e. the structure. My first attempt saw me programatically adding each series as siblings, which worked like a treat because I ended up with an ordered list and thus my order of rendering was maintained. I had this <Chart> <Series id="1">seriesText1</Series> <Series id="2">seriesText2</Series> <Series id="3">seriesText3</Series> <Series id="4">seriesText4</Series> </Chart> I'm in a muddle now ... how can I represent a series and a series that has children series. If some-one can give me a hint to how my tree should look (perhaps with a snippet on how to programatically add nodes to their parents) All the examples I have read usually have some container elements such as <ContactS> or <BookS> but my head says I have <series> some of them parent some of them children. Would appreciate a nudge in the right direction.

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