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• Rails 3 fields_for agressive loading?

  - by Seth

  Hi all, I'm trying to optimize (limit) queries in a view. I am using the fields_for function. I need to reference various properties of the object, such as username for display purposes. However, this is a rel table, so I need to join with my users table. The result is N sub-queries, 1 for each field in fields_for. It's difficult to explain, but I think you'll understand what I'm asking if I paste my code: <%= form_for @election do |f| %> <%= f.fields_for :voters do |voter| %> <%= voter.hidden_field :id %> <%= voter.object.user.preferred_name %> <% end %> <% end %> I have like 10,000 users, and many times each election will include all 10,000 users. That's 10,000 subqueries every time this view is loaded. I want fields_for to JOIN on users. Is this possible? I'd like to do something like: ... <%= f.fields_for :voters, :joins => :users do |voter| %> ... <% end %> ... But that, of course, doesn't work :(

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• TreeView update bug in the VB.NET

  - by CFP

  Consider the following code: Dim Working As Boolean = False Private Sub TreeView1_AfterCheck(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterCheck If Working Then Exit Sub Working = True e.Node.Checked = Not e.Node.Checked Working = False End Sub Private Sub TreeView1_MouseClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TreeView1.MouseClick If e.Button = Windows.Forms.MouseButtons.Right Then MsgBox("Checked = " & TreeView1.SelectedNode.Checked) End Sub Where TreeView1 is a TreeView added to the form, with CheckBoxes set to true and one node added. The code basically cancel any node checking occuring on the form. Single-clicking the top node to check it works well : your click is immediately canceled. Yet if you double-click the checkbox, it will display a tick. But verifying the check state through a right click will yield a Checked = False dialog. How come? Is it a bug (I'm using the latest .Net Framework 4.0, and he same occurs in 2.0), or am I doing something wrong here? Is there a work around? Thanks! EDIT: Additionally, the MouseDoubleClick event is not raised before you click once again. EDIT 2: Posted a bug report at Microsoft Connect

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• i not find how in powershell pass through http autentification then use a webservices (lotus/domino)

  - by user1716616

  We have here a domino/lotus webservices i want use with powershell. probleme is in front of webservices lotus admin ask a http autentification. how i can use this webservice?? here what i tryed first scrap the first page and get cookie. $url = "http://xxxxxxx/names.nsf?Login" $CookieContainer = New-Object System.Net.CookieContainer $postData = "Username=web.services&Password=jesuisunestar" $buffer = [text.encoding]::ascii.getbytes($postData) [net.httpWebRequest] $req = [net.webRequest]::create($url) $req.method = "POST" $req.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8" $req.Headers.Add("Accept-Language: en-US") $req.Headers.Add("Accept-Encoding: gzip,deflate") $req.Headers.Add("Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7") $req.AllowAutoRedirect = $false $req.ContentType = "application/x-www-form-urlencoded" $req.ContentLength = $buffer.length $req.TimeOut = 50000 $req.KeepAlive = $true $req.Headers.Add("Keep-Alive: 300"); $req.CookieContainer = $CookieContainer $reqst = $req.getRequestStream() $reqst.write($buffer, 0, $buffer.length) $reqst.flush() $reqst.close() [net.httpWebResponse] $res = $req.getResponse() $resst = $res.getResponseStream() $sr = new-object IO.StreamReader($resst) $result = $sr.ReadToEnd() this seem work but now no idea how i can use cookie with a webservicesproxy??? ps: i success have this to work with c# + visualstudio (just the class reference is autobuilt and i don't understand half of this but it allow me to use .CookieContenaire on the generated webservice )

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• Weird behavior of matching array keys after json_decode()

  - by arnorhs

  I've got some very weird behavior in my PHP code. I don't know if this is actually a good SO question, since it almost looks like a bug in PHP. I had this problem in a project of mine and isolated the problem: // json object that will be converted into an array $json = '{"5":"88"}'; $jsonvar = (array) json_decode($json); // notice: Casting to an array // Displaying the array: var_dump($jsonvar); // Testing if the key is there var_dump(isset($jsonvar["5"])); var_dump(isset($jsonvar[5])); That code outputs the following: array(1) { ["5"]=> string(2) "88" } bool(false) bool(false) The big problem: Both of those tests should produce bool(true) - if you create the same array using regular php arrays, this is what you'll see: // Let's create a similar PHP array in a regular manner: $phparr = array("5" => "88"); // Displaying the array: var_dump($phparr); // Testing if the key is there var_dump(isset($phparr["5"])); var_dump(isset($phparr[5])); The output of that: array(1) { [5]=> string(2) "88" } bool(true) bool(true) So this doesn't really make sense. I've tested this on two different installations of PHP/apache. You can copy-paste the code to a php file yourself to test it. It must have something to do with the casting from an object to an array.

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• Detect whether or not a specific attribute was valid on the model

  - by Sir Code-A-Lot

  Having created my own validation attribute deriving from System.ComponentModel.DataAnnotations.ValidationAttribute, I wish to be able to detect from my controller, whether or not that specific attribute was valid on the model. My setup: public class MyModel { [Required] [CustomValidation] [SomeOtherValidation] public string SomeProperty { get; set; } } public class CustomValidationAttribute : ValidationAttribute { public override bool IsValid(object value) { // Custom validation logic here } } Now, how do I detect from the controller whether validation of CustomValidationAttribute succeeded or not? I have been looking at the Exception property of ModelError in the ModelState, but I have no way of adding a custom exception to it from my CustomValidationAttribute. Right now I have resorted to checking for a specific error message in the ModelState: public ActionResult PostModel(MyModel model) { if(ModelState.Where(i => i.Value.Errors.Where((e => e.ErrorMessage == CustomValidationAttribute.SharedMessage)).Any()).Any()) DoSomeCustomStuff(); // The rest of the action here } And changed my CustomValidationAttribute to: public class CustomValidationAttribute : ValidationAttribute { public static string SharedMessage = "CustomValidationAttribute error"; public override bool IsValid(object value) { ErrorMessage = SharedMessage; // Custom validation logic here } } I don't like relying on string matching, and this way the ErrorMessage property is kind of misused. What are my options?

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• Session does not giving right records?

  - by Jugal

  I want to keep one session, but when I rollback transaction then transaction gets isActive=false, so I can not commit and rollback in next statements by using same transaction. then I need to create new transaction but what is going wrong here ? var session = NHibernateHelper.OpenSession();/* It returns new session. */ var transaction1 = session.BeginTransaction(); var list1 = session.Query<Make>().ToList(); /* It returs 4 records. */ session.Delete(list1[2]); /* After Rollback, transaction is isActive=false so I can not commit * and rollback from this transaction in future. so I need to create new transaction. */ transaction1.Rollback(); var transaction2 = session.BeginTransaction(); /* It returns 3 records. * I am not getting object(which was deleted but after that rollback) here why ? */ var list2 = session.Query<Make>().ToList(); Anyone have idea what is going wrong here ? I am not getting deleted object which was rollback.

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• Preloading Image Bug in IE6-8

  - by Kevin C.

  Page in question: http://phwsinc.com/our-work/one-rincon-hill.asp In IE6-8, when you click the left-most thumbnail in the gallery, the image never loads. If you click the thumbnail a second time, then it will load. I'm using jQuery, and here's my code that's powering the gallery: $(document).ready(function() { // PROJECT PHOTO GALLERY var thumbs = $('.thumbs li a'); var photoWrapper = $('div.photoWrapper'); if (thumbs.length) { thumbs.click( function(){ photoWrapper.addClass('loading'); var img_src = $(this).attr('href'); // The two lines below are what cause the bug in IE. They make the gallery run much faster in other browsers, though. var new_img = new Image(); new_img.src = img_src; var photo = $('#photo'); photo.fadeOut('slow', function() { photo.attr('src', img_src); photo.load(function() { photoWrapper.removeClass('loading'); photo.fadeIn('slow'); }); }); return false; }); } }); A coworker told me that he's always had problems with the js Image() object, and advised me to just append an <img /> element inside of a div set to display:none;, but that's a little messy for my tastes--I liked using the Image() object, it kept things nice and clean, no unnecessary added HTML markup. Any help would be appreciated. It still works without the image preloading, so if all else fails I'll just wrap the preloading in an if !($.browser.msie){ } and call it a day.

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• How to lazy load a data structure (python)

  - by Anton Geraschenko

  I have some way of building a data structure (out of some file contents, say): def loadfile(FILE): return # some data structure created from the contents of FILE So I can do things like puppies = loadfile("puppies.csv") # wait for loadfile to work kitties = loadfile("kitties.csv") # wait some more print len(puppies) print puppies[32] In the above example, I wasted a bunch of time actually reading kitties.csv and creating a data structure that I never used. I'd like to avoid that waste without constantly checking if not kitties whenever I want to do something. I'd like to be able to do puppies = lazyload("puppies.csv") # instant kitties = lazyload("kitties.csv") # instant print len(puppies) # wait for loadfile print puppies[32] So if I don't ever try to do anything with kitties, loadfile("kitties.csv") never gets called. Is there some standard way to do this? After playing around with it for a bit, I produced the following solution, which appears to work correctly and is quite brief. Are there some alternatives? Are there drawbacks to using this approach that I should keep in mind? class lazyload: def __init__(self,FILE): self.FILE = FILE self.F = None def __getattr__(self,name): if not self.F: print "loading %s" % self.FILE self.F = loadfile(self.FILE) return object.__getattribute__(self.F, name) What might be even better is if something like this worked: class lazyload: def __init__(self,FILE): self.FILE = FILE def __getattr__(self,name): self = loadfile(self.FILE) # this never gets called again # since self is no longer a # lazyload instance return object.__getattribute__(self, name) But this doesn't work because self is local. It actually ends up calling loadfile every time you do anything.

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• What is a simple way to add a timer to a method

  - by John

  The following is in C#. I'm trying to do something very simple (I think). I have a method that loads an XML document XDocument doc = XDocument.Load(uri); , but I don't want to tie up pc resources if there are issues (connectivity, document size, etc.). So I'd like to be able to add a timeout variable that will cut the method off after a given number of seconds. I'm a newbie when it comes to asynchronous programming and find it confusing that there are so many examples written so many different ways . . . and none of them appear simple. I'd like a simple solution, if possible. Here's my thoughts so far on possible solution paths: 1) A method that wraps the existing load public XDocument LoadXDocument(string uri, int timeout){ //code } 2) A wrapper, but as an extension method XDocument doc = XDocument.LoadWithTimeout(string uri, int timeout); 3) A generic extension method. Object obj = SomeStaticClass.LoadWithTimeout(??? method, int timeout); 3), on its face seems really nice, because it would mean being able to generically add timeouts to many different method calls and not specifically tied to one type of object, but I suspect that it is either i)impossible or ii) very difficult. Please assist. Thanks.

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• xpath php attributes not working?

  - by Jared

  Getting this error Call to a member function attributes() on a non-object I have found multiple answers to this on SO, but none of them seem to solve my problem? Here is the XML: <Routes> <Route type="source" name="incoming"> </Route> <Routes> Here is the PHP: $doc = new SimpleXMLElement('routingConfig.xml', null, true); class traverseXML { function getData() { global $doc; $routeCount = count($doc -> xpath("Route")); //this value returns correctly $routeArr = array(); for ($i = 1; $i <= $routeCount; $i++) { $name = $doc -> Route[$i] -> attributes() -> name; array_push($routeArr, $name); } return $routeArr; } } $traverseXML = new traverseXML; var_dump($traverseXML -> getData()); I understand what the error means, but how is it a non-object? How do I return the name attribute of Routes/Route[1] ?

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• Problem consuming a dataset via a .NET web service from Flex-ActionScript

  - by DEH

  Hi, I am returning a .NET dataset to Flex Actionscript via a web service. Actionscript snippet as follows: var websvc:WebService = new WebService(); websvc.useProxy=false; websvc.wsdl = "http://localhost:13229/test/mysvc.asmx?WSDL"; websvc.loadWSDL(); var operation:Operation = new Operation(null, "GetData"); operation.arguments.command="xx_gethierdata_"+mode+"_"+identifier; operation.addEventListener(ResultEvent.RESULT, onResultHandler, false, 0, true); operation.addEventListener(FaultEvent.FAULT, onFaultHandler, false, 0, true); operation.resultFormat="object"; websvc.operations = [operation]; operation.send(); Once in the onResultHandler function I have access to the datatable - I then want to grab the column names. The following code outputs my column names: for each (var tcolumn:Object in datatable.Columns){trace('Column:'+tcolumn);} This works ok, but the column names are encoded, so a column name that is actually "1-9" is output as "_x005B_1-9_x005D_" Anyone know the best way to decode the column name? I could replace all the encoding strings, but surely there is a better way? Thanks

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• How would I associate a "Note" class to 4+ classes without creating lookup table for each associatio

  - by Gthompson83

  Im creating a project tasklist application. I have project, section, task, issue classes, and would like to use one class to be able to add simple notes to any object instance of those classes. The task, issue tables both use a standard identity field as a primary key. The section table has a two field primary key. The project table has a single int primary key defined by the user. Is there a way to associate the note class with each of these without using a seperate lookup table for each class? I'm not so sure my original idea is a decent way to implement this. I considered the following (each variable mapping to a field n the notes table. Private _NoteId As Integer Private _ProjectId As Integer Private _SectionId As Integer Private _SectionId2 As Integer Private _TaskId As Integer Private _IssueId As Integer Private _Note As String Private _UserId As Guid Then I would be able to write seperate methods (getProjectNotes, getTaskNotes) to get notes attached to each class. I started writing this a few weeks ago but got pulled away before i could finish. When revisiting this code today my first thought "this is retarded". Thoughts on drawbacks to this design?

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• GWT + JDO + ArrayList

  - by dvieira

  Hi, I'm getting a Null ArrayList in a program i'm developing. For testing purposes I created this really small example that still has the same problem. I already tried diferent Primary Keys, but the problem persists. Any ideas or suggestions? 1-Employee class @PersistenceCapable(identityType = IdentityType.APPLICATION) public class Employee { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String key; @Persistent private ArrayList<String> nicks; public Employee(ArrayList<String> nicks) { this.setNicks(nicks); } public String getKey() { return key; } public void setNicks(ArrayList<String> nicks) { this.nicks = nicks; } public ArrayList<String> getNicks() { return nicks; } } 2-EmployeeService public class BookServiceImpl extends RemoteServiceServlet implements EmployeeService { public void addEmployee(){ ArrayList<String> nicks = new ArrayList<String>(); nicks.add("name1"); nicks.add("name2"); Employee employee = new Employee(nicks); PersistenceManager pm = PMF.get().getPersistenceManager(); try { pm.makePersistent(employee); } finally { pm.close(); } } /** * @return * @throws NotLoggedInException * @gwt.typeArgs <Employee> */ public Collection<Employee> getEmployees() { PersistenceManager pm = getPersistenceManager(); try { Query q = pm.newQuery("SELECT FROM " + Employee.class.getName()); Collection<Employee> list = pm.detachCopyAll((Collection<Employee>)q.execute()); return list; } finally { pm.close(); } } }

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• Execute files included in Resource folder

  - by Sumeet Pujari

  In WPF application where I have included some files in resources, I want to execute them on a button click. How do I specify a path in Process.Start(). private void button1_Click_2(object sender, RoutedEventArgs e) { Process.Start("test.txt"); } Or is there any other way? private void button1_Click_2(object sender, RoutedEventArgs e) { string path = System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) + @"\test.txt"; if (File.Exists(path)) { Process.Start(new ProcessStartInfo(path)); } else { MessageBox.Show("No file found"+path); } I added a message box and it showed No files found. :( EDIT: I Tried to check the path after publishing and this what i got. No File Found With a Path - C:\Users\Administrator\AppData\Local\Apps\2.0... test.txt Before I published the Application I got a path which id No File Found at ..project..\bin\Debug\test.txt which is obvious since my Resource file not included there its Under a Resource Folder and not Debug when i add a test file in debug it open without any problem. Can someone Help throwing some light on this case. EDIT: I want to open a file from Resource directory @ C:\Users\Administrator\Documents\Visual Studio 2010\Projects\FastFix\FastFix\Resources Which would be included in my project when i am going to publish it is going to run as a standalone application without installation.

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• XML digital signature interface

  - by yeekang

  I am trying to call a WebService and it requires me to prepare an XML digital signature interface. I came across this website and it shows how to sign an XML document. My problem now is that I do not create the XML document myself. My code is as follows: string myResult; GenericWS.ServicesService a = new GenericWS.ServicesService(); GenericWS.Service2 b = new GenericWS.Service2(); b.Something = "3"; X509Certificate cert = X509Certificate.CreateFromCertFile("C:\\somepath\\somecert.cer"); a.ClientCertificates.Add(cert); ServicePointManager.ServerCertificateValidationCallback = delegate (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; }; myResult= a.WSRequest(b).WSReturnValue.ToString(); Label1.Text = myResult; Basically, the WSRequest() will generate the body of the SOAP message. However, in order to sign the SOAP message, I need to pass in the XML file that needs to be signed. I tried to serialize the object and cast it as XML and pass it into the signature interface but I do not have another method that I can invoke to call the webmethod. Is there any other solution?

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• Can this line of code really throw an IndexOutOfRange exception?

  - by Jonathan M

  I am getting an IndexOutOfRange exception on the following line of code: var searchLastCriteria = (SearchCriteria)Session.GetSafely(WebConstants.KeyNames.SEARCH_LAST_CRITERIA); I'll explain the above here: SearchCriteria is an Enum with only two values Session is the HttpSessionState GetSafely is an extension method that looks like this: public static object GetSafely(this HttpSessionState source, string key) { try { return source[key]; } catch (Exception exc) { log.Info(exc); return null; } } WebConstants.KeyNames.SEARCH_LAST_CRITERIA is simply a constant I've tried everything to replicate this error, but I cannot reproduce it. I am beginning to think the stack trace is wrong. I thought perhaps the exception was actually coming from the GetSafely call, but it is swallowing the exceptions, so that can't be the case, and even if it was, it should show up in the stack trace. Is there anything in the line of code above that could possible throw an IndexOutOfRange exception? I know the line will throw an NullReferenceException if GetSafely returns null, and it will also throw an InvalidCastException if it returns anything that cannot be cast to SearchCriteria, but an IndexOutOfRange exception? I'm scratching my head here. Here is the stack trace: $LOG--> 2010-06-11 07:01:33,814 [ERROR] SERVERA (14) Web.Global - Index was outside the bounds of the array. System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.IndexOutOfRangeException: Index was outside the bounds of the array. at IterateSearchResult(Boolean next) in C:\Projects\Web\UserControls\AccountHeader.ascx.cs:line 242 at nextAccountLink_Click(Object sender, EventArgs e) in C:\Projects\Web\UserControls\AccountHeader.ascx.cs:line 232

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• problem with converting simple code from Winform to silverlight app.

  - by Sara

  Hi. I have this code for window form application and I have been attempting to convert it to a Silverlight application but it does not work!. There is a Textbox and I attached KeyDown event handler to it. when the user press the arrow key ( left or right) while the focus on the textbox, it will write . or -. When it is window form i used e.KeyCode and Keys.Right and its works great but when it is silverlight I used e.Key and key.Right and the program doesn't work good because the arrows do the 2 functions moving and write ./-. How I can work this out in Silverlight? (My English not good) The code ( window form): private void textBox1_KeyDown(object sender, KeyEventArgs e) { if (sender is TextBox) { TextBox textBox = (TextBox)sender; if (e.KeyCode == Keys.Left || e.KeyCode == Keys.Right) { e.Handled = true; char insert; if (e.KeyCode == Keys.Left) { insert = '.'; } else { insert = '-'; } int i = textBox.SelectionStart; textBox.Text = textBox.Text.Insert(i, insert.ToString()); textBox.Select(i + 1, 0); } } } (and Silverlight): private void textBox1_KeyDown(object sender, KeyEventArgs e) { if (sender is TextBox) { TextBox textBox = (TextBox)sender; if (e.Key == Key.Left || e.Key == Key.Right) { e.Handled = true; char insert; if (e.Key == Key.Left) { insert = '.'; } else { insert = '-'; } int i = textBox.SelectionStart; textBox.Text = textBox.Text.Insert(i, insert.ToString()); textBox.Select(i + 1, 0); } } } I don't understand, is there huge different effect between using Keycode/Keys and Key/Key or because something else?

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• How does Access 2007's moveNext/moveFirst/, etc., feature work?

  - by Chris M

  I'm not an Access expert, but am an SQL expert. I inherited an Access front-end referencing a SQL 2005 database that worked OK for about 5000 records, but is failing miserably for 800k records... Behind the scenes in the SQL profiler & activity manager I see some kind of Access query like: SELECT "MS1"."id" FROM "dbo"."customer" "MS1" ORDER BY "MS1"."id" The MS prefix doesn't appear in any Access code I can see. I'm suspicious of the built-in Access navigation code: DoCmd.GoToRecord , , acNext The GoToRecord has AcRecord constant, which includes things like acFirst, acLast, acNext, acPrevious and acGoTo. What does it mean in a database context to move to the "next" record? This particular table uses an identity column as the PK, so is it internally grabbing all the IDs and then moving to the one that is the next highest??? If so, how would it work if a table was comprised of three different fields for the PK? Or am I on the wrong track, and something else in Access is calling that statement? Unfortunately I see a ton of prepared statements in the profiler. THanks!

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• [VB.Net] TreeView update bug in the .net framework

  - by CFP

  Consider the following code: Dim Working As Boolean = False Private Sub TreeView1_AfterCheck(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterCheck If Working Then Exit Sub Working = True e.Node.Checked = Not e.Node.Checked Working = False End Sub Private Sub TreeView1_MouseClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TreeView1.MouseClick If e.Button = Windows.Forms.MouseButtons.Right Then MsgBox("Checked = " & TreeView1.SelectedNode.Checked) End Sub Where TreeView1 is a TreeView added to the form, with CheckBoxes set to true and one node added. The code basically cancel any node checking occuring on the form. Single-clicking the top node to check it works well : your click is immediately canceled. Yet if you double-click the checkbox, it will display a tick. But verifying the check state through a right click will yield a Checked = False dialog. How come? Is it a bug (I'm using the latest .Net Framework 4.0, and he same occurs in 2.0), or am I doing something wrong here? Is there a work around? Thanks! EDIT: Additionally, the MouseDoubleClick event is not raised before you click once again.

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• How to animate a path like it's being drawn, dot by dot? (Raphael.js)

  - by Anton

  How to animate a vector path like it's being drawn by hand? In other words, slowly show the path pixel by pixel. I'm using Raphaël.js, but if your answer is not library specific—like maybe there's some general programming pattern for doing that kind of thing (I'm fairly new to vector animation)—it's welcome! Update I know it's easy to do with straight paths, as easy as an example on that page:: path("M114 253").animate({path: "M114 253 L 234 253"}); But try to change code on that page, say, this way:: path("M114 26").animate({path: "M114 26 C 24 23 234 253 234 253"}); And you'll see what I mean. Path is certainly animated from it initial state (point "M114 26") to the end state (curve "C 24 23 234 253 234 253" starting on point "M114 26"), but not in a way specified in question, not like it's being drawn. (Sorry for not making clear from the start that I don't mean animating straight lines.) I don't see how animateAlong can do that either. It can animate an object along a path, and how can I make this path to gradually show itself while object is being animated along it?

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• Is method reference caching a good idea in Java 8?

  - by gexicide

  Consider I have code like the following: class Foo { Y func(X x) {...} void doSomethingWithAFunc(Function<X,Y> f){...} void hotFunction(){ doSomethingWithAFunc(this::func); } } Consider that hotFunction is called very often. Would it then be advisable to cache this::func, maybe like this: class Foo { Function<X,Y> f = this::func; ... void hotFunction(){ doSomethingWithAFunc(f); } } As far as my understanding of java method references goes, the Virtual Machine creates an object of an anonymous class when a method reference is used. Thus, caching the reference would create that object only once while the first approach creates it on each function call. Is this correct? Should method references that appear at hot positions in the code be cached or is the VM able to optimize this and make the caching superfluous? Is there a general best practice about this or is this highly VM-implemenation specific whether such caching is of any use?

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• Generating all possible subsets of a given QuerySet in Django

  - by Glen

  This is just an example, but given the following model: class Foo(models.model): bar = models.IntegerField() def __str__(self): return str(self.bar) def __unicode__(self): return str(self.bar) And the following QuerySet object: foobar = Foo.objects.filter(bar__lt=20).distinct() (meaning, a set of unique Foo models with bar <= 20), how can I generate all possible subsets of foobar? Ideally, I'd like to further limit the subsets so that, for each subset x of foobar, the sum of all f.bar in x (where f is a model of type Foo) is between some maximum and minimum value. So, for example, given the following instance of foobar: >> print foobar [<Foo: 5>, <Foo: 10>, <Foo: 15>] And min=5, max=25, I'd like to build an object (preferably a QuerySet, but possibly a list) that looks like this: [[<Foo: 5>], [<Foo: 10>], [<Foo: 15>], [<Foo: 5>, <Foo: 10>], [<Foo: 5>, <Foo: 15>], [<Foo: 10>, <Foo: 15>]] I've experimented with itertools but it doesn't seem particularly well-suited to my needs. I think this could be accomplished with a complex QuerySet but I'm not sure how to start.

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• issue with tab bar view displaying a compound view

  - by ambertch

  I created a tab bar application, and I make the first tab a table. So I create a tableView controller, and go about setting the class identity of the view controller for the first tab to my tableView controller. This works fine, and I see the contents of the table filling up the whole screen. However, this is not what I actually want in the end goal - I would like a compound window having multiple views: - the aforementioned table - a custom view with data in it So what I do is create a nib for this content (call it contentNib), change the tab's class from the tableView controller to a generic UIViewController, and set the nib of that tab to this new contentNib. In this new contentNib I drag on a tableView and set File's Owner to the TableViewController. I then link the dataSource and delegate to file's owner (which is TableViewController). Surprisingly this does not work and I receive the error: **Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x3b0f910'** This is bewildering to me since the file's owner is the TableViewController, which has been assigned to be both the dataSource and delegate. Does someone have either insight into my confusions, or a link to an example of how to have a compound view include a tableView? *update* I see this in the Apple TableView programming guide: "Note: You should use a UIViewController subclass rather than a subclass of UITableViewController to manage a table view if the view to be managed is composed of multiple subviews, one of which is a table view. The default behavior of the UITableViewController class is to make the table view fill the screen between the navigation bar and the tab bar (if either are present)." <----- I don't really get what this is telling me to do though... if someone can explain or point me to an example I'd be much appreciated!

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• Completed Event not triggering for web service on some systems

  - by Farukh

  Hi, This is rather weird issue that I am facing with by WCF/Silverlight application. I am using a WCF to get data from a database for my Silverlight application and the completed event is not triggering for method in WCF on some systems. I have checked the called method executes properly has returns the values. I have checked via Fiddler and it clearly shows that response has the returned values as well. However the completed event is not getting triggered. Moreover in few of the systems, everything is fine and I am able to process the returned value in the completed method. Any thoughts or suggestions would be greatly appreciated. I have tried searching around the web but without any luck :( Following is the code.. Calling the method.. void RFCDeploy_Loaded(object sender, RoutedEventArgs e) { btnSelectFile.IsEnabled = true; btnUploadFile.IsEnabled = false; btnSelectFile.Click += new RoutedEventHandler(btnSelectFile_Click); btnUploadFile.Click += new RoutedEventHandler(btnUploadFile_Click); RFCChangeDataGrid.KeyDown += new KeyEventHandler(RFCChangeDataGrid_KeyDown); btnAddRFCManually.Click += new RoutedEventHandler(btnAddRFCManually_Click); ServiceReference1.DataService1Client ws = new BEVDashBoard.ServiceReference1.DataService1Client(); ws.GetRFCChangeCompleted += new EventHandler<BEVDashBoard.ServiceReference1.GetRFCChangeCompletedEventArgs>(ws_GetRFCChangeCompleted); ws.GetRFCChangeAsync(); this.BusyIndicator1.IsBusy = true; } Completed Event.... void ws_GetRFCChangeCompleted(object sender, BEVDashBoard.ServiceReference1.GetRFCChangeCompletedEventArgs e) { PagedCollectionView view = new PagedCollectionView(e.Result); view.GroupDescriptions.Add(new PropertyGroupDescription("RFC")); RFCChangeDataGrid.ItemsSource = view; foreach (CollectionViewGroup group in view.Groups) { RFCChangeDataGrid.CollapseRowGroup(group, true); } this.BusyIndicator1.IsBusy = false; } Please note that this WCF has lots of other method as well and all of them are working fine.... I have problem with only this method... Thanks...

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• What kind of data do I pass into a Django Model.save() method?

  - by poswald

  Lets say that we are getting POSTed a form like this in Django: rate=10 items= [23,12,31,52,83,34] The items are primary keys of an Item model. I have a bunch of business logic that will run and create more items based on this data, the results of some db lookups, and some business logic. I want to put that logic into a save signal or an overridden Model.save() method of another model (let's call it Inventory). The business logic will run when I create a new Inventory object using this form data. Inventory will look like this: class Inventory(models.Model): picked_items = models.ManyToManyField(Item, related_name="items_picked_set") calculated_items = models.ManyToManyField(Item, related_name="items_calculated_set") rate = models.DecimalField() ... other fields here ... New calculated_items will be created based on the passed in items which will be stored as picked_items. My question is this: is it better for the save() method on this model to accept: the request object (I don't really like this coupling) the form data as arguments or kwargs (a list of primary keys and the other form fields) a list of Items (The caller form or view will lookup the list of Items and create a list as well as pass in the other form fields) some other approach? I know this is a bit subjective, but I was wondering what the general idea is. I've looked through a lot of code but I'm having a hard time finding a pattern I like.

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