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  • @PrePersist with entity inheritance

    - by gerry
    I'm having some problems with inheritance and the @PrePersist annotation. My source code looks like the following: _the 'base' class with the annotated updateDates() method: @javax.persistence.Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public class Base implements Serializable{ ... @Id @GeneratedValue protected Long id; ... @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date creationDate; @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date lastModificationDate; ... public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } public Date getLastModificationDate() { return lastModificationDate; } public void setLastModificationDate(Date lastModificationDate) { this.lastModificationDate = lastModificationDate; } ... @PrePersist protected void updateDates() { if (creationDate == null) { creationDate = new Date(); } lastModificationDate = new Date(); } } _ now the 'Child' class that should inherit all methods "and annotations" from the base class: @javax.persistence.Entity @NamedQueries({ @NamedQuery(name=Sensor.QUERY_FIND_ALL, query="SELECT s FROM Sensor s") }) public class Sensor extends Entity { ... // additional attributes @Column(nullable=false) protected String value; ... // additional getters, setters ... } If I store/persist instances of the Base class to the database, everything works fine. The dates are getting updated. But now, if I want to persist a child instance, the database throws the following exception: MySQLIntegrityConstraintViolationException: Column 'CREATIONDATE' cannot be null So, in my opinion, this is caused because in Child the method "@PrePersist protected void updateDates()" is not called/invoked before persisting the instances to the database. What is wrong with my code?

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  • Searching with a UISearchbar is slow and blocking the main thread.

    - by Robert
    I have a Table with over 3000 entries and searching is very slow. At the moment I am doing just like in the 'TableSearch' example code (but without scopes) - (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString { [self filterContentForSearchText: searchString]; // Return YES to cause the search result table view to be reloaded. return YES; } And the filterContentForSearchText method is as follows: - (void) filterContentForSearchText:(NSString*)searchText { // Update the filtered array based on the search text // First clear the filtered array. [filteredListContent removeAllObjects]; // Search the main list whose name matches searchText // add items that match to the filtered array. if (fetchedResultsController.fetchedObjects) { for (id object in fetchedResultsController.fetchedObjects) { NSString* searchTarget = [tableTypeDelegate getStringForSearchFilteringFromObject:object]; if ([searchTarget rangeOfString:searchText options:(NSCaseInsensitiveSearch|NSDiacriticInsensitiveSearch)].location != NSNotFound) { [filteredListContent addObject:object]; } } } } My question is twofold: How do can I make the searching process faster? How can I stop the search from blocking the main thread? i.e. stop it preventing the user from typing more characters. For the second part, I tried "performSelector:withObject:afterDelay:" and "cancelPreviousPerformRequests..." without much success. I suspect that I will need to use threading instead, but I do not have much experience with it.

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  • Getting values from the html to the controller

    - by tina
    Hi, I'm trying to access the values a user introduces in a table from my controller. This table is NOT part of the model, and the view source code is something like: <table id="tableSeriales" summary="Seriales" class="servicesT" cellspacing="0" style="width: 100%"> <tr> <td class="servHd">Seriales</td> </tr> <tr id="t0"> <td class="servBodL"> <input id="0" type="text" value="1234" onkeypress = "return handleKeyPress(event, this.id);"/> <input id="1" type="text" value="578" onkeypress = "return handleKeyPress(event, this.id);"/> . . . </td> </tr> </table> How can I get those values (1234, 578) from the controller? Receiving a formcollection doesn't work since it does not get the table... Thank you.

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  • Javascript problem with location.href.

    - by Patrick
    Hello! I have a textbox and whenever the user presses a key it's checked to see if the user pressed enter. If the enter key is pressed, i want to add all the info in the textbox and transfer the user to a different url. <script language="javascript" type="text/javascript"> function checkEnter(e){ //e is event object passed from function invocation var characterCode; if(e && e.which){ //if which property of event object is supported (NN4) e = e; characterCode = e.which; //character code is contained in NN4's which property } else{ e = event; characterCode = e.keyCode; //character code is contained in IE's keyCode property } if (characterCode == 13) { //if generated character code is equal to ascii 13 (if enter key) var searchLink = '/Search/?Keywords=' + document.getElementById('<%= searchBox.ClientID %>').value; transferUser(searchLink); return false; } else{ return true; } } function transferUser(url) { window.location.href = url; window.location.replace(url); } </script> Search: <input name="ctl00$searchBox" type="text" id="ctl00_searchBox" class="header_line_search_box_textbox" onKeyPress="checkEnter(event);" /> I have tried every possible combination, but nothing happens. The site just refreshes itself. I also need somehow to convert the text from the user to html safe, must like the HttpUtility.EncodeUrl in aspx.

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  • Question about Client IDs

    - by George
    I have a user control that is emmitting javascript using the ClientId function. For example: Out &= "ValidatorHookupControlID(" & Quote & ddlMonth.ClientID & Quote & "), document.all(" & Quote & CustomValidator1.ClientID & Quote & "));" & vbCrLf It appears to me that the ClientID function DOES not return the ultimate ID that is sent to the browser. Instead, the ClientID function only appears to be aware of its current parent control, which in this case is a the User Control and so the ID that is returned is the ID "dtmPassportExpirationDate_ddlMonth" When in fact the usercontrol is included in a master page and the ultimate ID that is used is: "ctl00_phPageContent_dtmPassportExpirationDate_ddlMonth" I may be nuts, but that's what it appears to be doing. I expect that the ClientID function would return the ultimate ID used in the HTML. Am I missing something?

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  • Controller class not available in Add View ASP.NET MVC

    - by Tassadaque
    Hi I have created the following controller i want to add view that should have the data access class UserMagnament.Controller.menuitems but when i add view by right clicking on view folder,it is not showing "UserMagnament.Controller.menuitems" in add data class using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using UserManagement.Models; namespace UserManagement.Controllers { public class menuitems { EvoLetDataContext db1 = new EvoLetDataContext(); public menuitems() { } public IQueryable<UMUserType> menuitems() { return db1.UMUserTypes; //this.Packages = _SysPackage; //this.Modules = _SysModule; } public List<SysPackage> Packages { get; private set; } public List<SysModule> Modules { get; private set; } } public class Default1Controller : Controller { // // GET: /Default1/ public ActionResult Index() { return View(new menuitems()); } } }

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  • How do you pass a BitmapImage from a background thread to the UI thread in WPF?

    - by DanM
    I have a background thread that generates a series of BitmapImage objects. Each time the background thread finishes generating a bitmap, I would like to show this bitmap to the user. The problem is figuring out how to pass the BitmapImage from the background thread to the UI thread. This is an MVVM project, so my view has an Image element: <Image Source="{Binding GeneratedImage}" /> My view-model has a property GeneratedImage: private BitmapImage _generatedImage; public BitmapImage GeneratedImage { get { return _generatedImage; } set { if (value == _generatedImage) return; _generatedImage= value; RaisePropertyChanged("GeneratedImage"); } } My view-model also has the code that creates the background thread: public void InitiateGenerateImages(List<Coordinate> coordinates) { ThreadStart generatorThreadStarter = delegate { GenerateImages(coordinates); }; var generatorThread = new Thread(generatorThreadStarter); generatorThread.ApartmentState = ApartmentState.STA; generatorThread.IsBackground = true; generatorThread.Start(); } private void GenerateImages(List<Coordinate> coordinates) { foreach (var coordinate in coordinates) { var backgroundThreadImage = GenerateImage(coordinate); // I'm stuck here...how do I pass this to the UI thread? } } I'd like to somehow pass backgroundThreadImage to the UI thread, where it will become uiThreadImage, then set GeneratedImage = uiThreadImage so the view can update. I've looked at some examples dealing with the WPF Dispatcher, but I can't seem to come up with an example that addresses this issue. Please advise.

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

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

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  • How To Share Information Between Django and Javascript?

    - by Randy
    So I am pretty new to both Django and Javascript (I am using JQuery) and I am wondering if I am doing a hack or if there are more slick ways to send client-side displayed database ids to the django server-side. Here is my process: I have a dataTable (http://datatables.net) that I am displaying rows of data by using the bProcessing option to use AJAX to retrieve records from the database. The URL in my urls.py is something like: url(r'^assets/activitylog/(?P<cid>.*)$', views.getActivityTable_ajax, name="activitylog_table"), and my dataTable ajax-relavant code is something like: "sAjaxSource": "/assets/activitylog/" + getIDFromHTML(), where the javascript function getIDFromHTML() grabs <cid> that is used by the Django view is simply: function getIDFromHTML(){ // Simply return the text in the #release_id div element from the HTML return $("#release_id").html(); }; This is the part that seems "hacky" to me. I am inserting into my template code the database id that I am using in the datatables URL (with display:none in the css) just so I can pass it back to the view. Most of this is necessitated because one cannot use django template tags in the javascript code unless the code is embedded into the HTML itself, which I am not (and will not) do. The only other thing that I have found is to change the URL to get rid of the parameter passed in to: url(r'^assets/activitylog', views.getActivityTable_ajax, name="activitylog_table"), and change the view code to: def getActivityTable_ajax(request): """Returns the activity for a given pid from HTTP GET ajax reqest""" pid = int(urlparse.urlparse(request.META['HTTP_REFERER']).path.split('/')[-1]) # rest of view code here... since the id that I need is on the end of this referer url. This way I don't have to monkey around with embedding the hidden database id into the HTML and passing it back to via ajax the the table population view code. Is it okay to use HTTP_REFERER in the request object in this manner? Am I going about this in the totally wrong way? Thanks in advance!

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  • How to make a request from an android app that can enter a Spring Security secured webservice method

    - by johnrock
    I have a Spring Security (form based authentication) web app running CXF JAX-RS webservices and I am trying to connect to this webservice from an Android app that can be authenticated on a per user basis. Currently, when I add an @Secured annotation to my webservice method all requests to this method are denied. I have tried to pass in credentials of a valid user/password (that currently exists in the Spring Security based web app and can log in to the web app successfully) from the android call but the request still fails to enter this method when the @Secured annotation is present. The SecurityContext parameter returns null when calling getUserPrincipal(). How can I make a request from an android app that can enter a Spring Security secured webservice method? Here is the code I am working with at the moment: Android call: httpclient.getCredentialsProvider().setCredentials( //new AuthScope("192.168.1.101", 80), new AuthScope(null, -1), new UsernamePasswordCredentials("joeuser", "mypassword")); String userAgent = "Android/" + getVersion(); HttpGet httpget = new HttpGet(MY_URI); httpget.setHeader("User-Agent", userAgent); httpget.setHeader("Content-Type", "application/xml"); HttpResponse response; try { response = httpclient.execute(httpget); HttpEntity entity = response.getEntity(); ... parse xml Webservice Method: @GET @Path("/payload") @Produces("application/XML") @Secured({"ROLE_USER","ROLE_ADMIN","ROLE_GUEST"}) public Response makePayload(@Context Request request, @Context SecurityContext securityContext){ Payload payload = new Payload(); payload.setUsersOnline(new Long(200)); if (payload == null) { return Response.noContent().build(); } else{ return Response.ok().entity(payload).build(); } }

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  • Gui problem after rewriting to MVC

    - by trevor_nise
    I'm practicing MVC style programming. I have a Mastermind game in a single file, working with no problems (maybe apart of the fact that "Check" button is invisible at start). http://paste.pocoo.org/show/226726/ But when I've rewritten it to model, view, controller files - when I click on empty Pin (that should be updated, and repainted with new color) - noting happens. Can anybody see any problems here ? I've tried placing repaint() in different places, but it simply does not work at all :/ Main : public class Main { public static void main(String[] args){ Model model = new Model(); View view = new View("Mastermind", 400, 590, model); Controller controller = new Controller(model, view); view.setVisible(true); } } Model : import java.util.Random; public class Model{ static final int LINE = 5, SCORE = 10, OPTIONS = 20; Pin pins[][] = new Pin[21][LINE]; int combination[] = new int[LINE]; int curPin = 0; int turn = 1; Random generator = new Random(); int repaintPin; boolean pinsRepaint=false; int pinsToRepaint; boolean isUpdate = true, isPlaying = true, isRowFull = false; static final int HIT_X[] = {270,290,310,290,310}, HIT_Y[] = {506,496,496,516,516}; public Model(){ for ( int i=0; i < SCORE; i++ ){ for ( int j = 0; j < LINE; j++ ){ pins[i][j] = new Pin(20,0); pins[i][j].setPosition(j*50+30,510-i*50); pins[i+SCORE][j] = new Pin(8,0); pins[i+SCORE][j].setPosition(HIT_X[j],HIT_Y[j]-i*50); } } for ( int i=0; i < LINE; i++ ){ pins[OPTIONS][i] = new Pin( 20, i+2 ); pins[OPTIONS][i].setPosition( 370,i * 50 + 56); } } void fillHole(int color) { pins[turn-1][curPin].setColor(color+1); pinsRepaint = true; pinsToRepaint = turn; curPin = (curPin+1) % LINE; if (curPin == 0){ isRowFull = true; } pinsRepaint = false; pinsToRepaint = 0; } void check() { int junkPins[] = new int[LINE], junkCode[] = new int[LINE]; int pinCount = 0, pico = 0; for ( int i = 0; i < LINE; i++ ) { junkPins[i] = pins[turn-1][i].getColor(); junkCode[i] = combination[i]; } for ( int i = 0; i < LINE; i++ ){ if (junkPins[i]==junkCode[i]) { pins[turn+SCORE][pinCount].setColor(1); pinCount++; pico++; junkPins[i] = 98; junkCode[i] = 99; } } for ( int i = 0; i < LINE; i++ ){ for ( int j = 0; j < LINE; j++ ) if (junkPins[i]==junkCode[j]) { pins[turn+SCORE][pinCount].setColor(2); pinCount++; junkPins[i] = 98; junkCode[j] = 99; j = LINE; } } pinsRepaint = true; pinsToRepaint = turn + SCORE; pinsRepaint = false; pinsToRepaint=0; if ( pico == LINE ){ isPlaying = false; } else if ( turn >= 10 ){ isPlaying = false; } else{ curPin = 0; isRowFull = false; turn++; } } void combination() { for ( int i = 0; i < LINE; i++ ){ combination[i] = generator.nextInt(6) + 1; } } } class Pin{ private int color, X, Y, radius; public Pin(){ X = 0; Y = 0; radius = 0; color = 0; } public Pin( int r,int c ){ X = 0; Y = 0; radius = r; color = c; } public int getX(){ return X; } public int getY(){ return Y; } public int getRadius(){ return radius; } public void setRadius(int r){ radius = r; } public void setPosition( int x,int y ){ this.X = x ; this.Y = y ; } public void setColor( int c ){ color = c; } public int getColor() { return color; } } View: import java.awt.*; import javax.swing.*; public class View extends Frame{ Model model; JButton checkAnswer; private JPanel button; private static final Color COLORS[] = {Color.black, Color.white, Color.red, Color.yellow, Color.green, Color.blue, new Color(7, 254, 250)}; public View(String name, int w, int h, Model m){ model = m; setTitle( name ); setSize( w,h ); setResizable( false ); this.setLayout(new BorderLayout()); button = new JPanel(); button.setSize( new Dimension(400, 100)); button.setVisible(true); checkAnswer = new JButton("Check"); checkAnswer.setSize( new Dimension(200, 30)); button.add( checkAnswer ); this.add( button, BorderLayout.SOUTH); button.setVisible(true); } @Override public void paint( Graphics g ) { g.setColor( new Color(238, 238, 238)); g.fillRect( 0,0,400,590); for ( int i=0; i < model.pins.length; i++ ) { paintPins(model.pins[i][0],g); paintPins(model.pins[i][1],g); paintPins(model.pins[i][2],g); paintPins(model.pins[i][3],g); paintPins(model.pins[i][4],g); } } @Override public void update( Graphics g ) { if ( model.isUpdate ) { paint(g); } else { model.isUpdate = true; paintPins(model.pins[model.repaintPin-1][0],g); paintPins(model.pins[model.repaintPin-1][1],g); paintPins(model.pins[model.repaintPin-1][2],g); paintPins(model.pins[model.repaintPin-1][3],g); paintPins(model.pins[model.repaintPin-1][4],g); } } void repaintPins( int pin ) { model.repaintPin = pin; model.isUpdate = false; repaint(); } public void paintPins(Pin p, Graphics g ){ int X = p.getX(); int Y = p.getY(); int color = p.getColor(); int radius = p.getRadius(); int x = X-radius; int y = Y-radius; if (color > 0){ g.setColor( COLORS[color]); g.fillOval( x,y,2*radius,2*radius ); } else{ g.setColor( new Color(238, 238, 238) ); g.drawOval( x,y,2*radius-1,2*radius-1 ); } g.setColor( Color.black ); g.drawOval( x,y,2*radius,2*radius ); } } Controller: import java.awt.*; import java.awt.event.*; public class Controller implements MouseListener, ActionListener { private Model model; private View view; public Controller(Model m, View v){ model = m; view = v; view.addWindowListener( new WindowAdapter(){ public void windowClosing(WindowEvent e){ System.exit(0); } }); view.addMouseListener(this); view.checkAnswer.addActionListener(this); model.combination(); } public void actionPerformed( ActionEvent e ) { if(e.getSource() == view.checkAnswer){ if(model.isRowFull){ model.check(); } } } public void mousePressed(MouseEvent e) { Point mouse = new Point(); mouse = e.getPoint(); if (model.isPlaying){ if (mouse.x > 350) { int button = 1 + (int)((mouse.y - 32) / 50); if ((button >= 1) && (button <= 5)){ model.fillHole(button); if(model.pinsRepaint){ view.repaintPins( model.pinsToRepaint ); } } } } } public void mouseClicked(MouseEvent e) {} public void mouseReleased(MouseEvent e){} public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} }

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  • accessing a method from a button within a class?

    - by flo
    #import "GameObject.h" #import "Definitions.h" @implementation GameObject @synthesize owner; @synthesize state; @synthesize mirrored; @synthesize button; @synthesize switcher; - (id) init { if ( self = [super init] ) { [self setOwner: EmptyField]; button = [UIButton buttonWithType:UIButtonTypeCustom]; [self setSwitcher: FALSE]; } return self; } - (UIButton*) display{ button.frame = CGRectMake(0, 0, GO_Width, GO_Height); [button setBackgroundImage:[UIImage imageNamed:BlueStone] forState:UIControlStateNormal]; [button addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside]; return button; } -(void)buttonPressed:(id) sender { //... } } - (void) dealloc { [super dealloc]; } @end Hi! i would like to know if the above is possible somehow within a class (in my case it is called GameObject) or if i HAVE to have the button call a methode in the viewcontroller... the above results with the app crashing. i would call display within a loop on the viewcontroller and id like to change some of the GameObjects instance variables within buttonPressed. Also id like to change some other stuff by calling some other methods from within buttonPressed but i think that will be the lesser of my problems ;) also id like to know how i can pass some variables to the buttonPressed method... cant find it anywhere :( help on this one would be much appreciated ;) thanks flo

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  • innerHTML in IE?

    - by froufrou
    I'm having trouble using innerHTML with my radio type button. <table align="center"> <div class='main'> <span id="js" class='info'> <label><input type="radio" name="js" value="0" size="<?php echo $row['size']; ?>" onclick="js(this.value, this.size);" /><img src="arrowup.png"/></label> <br /> <label><input type="radio" name="js" value="1" size="<?php echo $row['size']; ?>" onclick="js(this.value, this.size);" /><img src="arrowdown.png"/></label> </span> </div> </table> My .js looks like this: var xmlhttp; function getVote(a,b) { xmlhttp=GetXmlHttpObject(); if (xmlhttp==null) { alert ("Browser does not support HTTP Request"); return; } var url="js.php"; url=url+"?js="+a; url=url+"&id="+b; url=url+"&sid="+Math.random(); xmlhttp.onreadystatechange=stateChanged; xmlhttp.open("GET",url,true); xmlhttp.send(null); } function stateChanged() { if (xmlhttp.readyState==4) { document.getElementById("js").innerHTML=xmlhttp.responseText; } } function GetXmlHttpObject() { var objXMLHttp=null; if (window.XMLHttpRequest) { objXMLHttp=new XMLHttpRequest(); } else if (window.ActiveXObject) { objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP"); } return objXMLHttp; } This doesn't work in IE only! Any help?

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  • HTML converted to jQuery collection not searchable with selectors?

    - by jimp
    I am trying to dynamically load a page using $.get(), parse the return with var $content = $(data), and ultimately use selectors to find only certain parts of the document. Only I cannot figure out why the jQuery collection returned from $(data) does not find some very basic selectors. I set up a jsFiddle to illustrate the problem using a very small string of HTML. <html> <head> <title>See Our Events</title> </head> <body><div id="content">testing</div></body> </html> I want to find the <title> node. var html = "<html>\n"+ "<head>\n"+ " <title>See Our Events</title>\n"+ "</head>\n"+ "<body><div id=\"content\">testing</div></body>\n"+ "</html>"; var $content = $(html); console.log($content.find('title').length); // Logs 0. Why? If I wrap a <div> around the HTML, then the selector works. (But if you look at the jsFiddle, other variations of the selector still do not work!) var html = "<div><html>\n"+ "<head>\n"+ " <title>See Our Events</title>\n"+ "</head>\n"+ "<body><div id=\"content\">testing</div></body>\n"+ "</html></div>"; var $content = $(html); console.log($content.find('title').length); // Logs 1. Please look at the jsFiddle, too. It contains more examples than my code here to keep the post easier to read. Why does my otherwise very basic selector not return the title node?

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  • Very slow guards in my monadic random implementation (haskell)

    - by danpriduha
    Hi! I was tried to write one random number generator implementation, based on number class. I also add there Monad and MonadPlus instance. What mean "MonadPlus" and why I add this instance? Because of I want to use guards like here: -- test.hs -- import RandomMonad import Control.Monad import System.Random x = Rand (randomR (1 ::Integer, 3)) ::Rand StdGen Integer y = do a <-x guard (a /=2) guard (a /=1) return a here comes RandomMonad.hs file contents: -- RandomMonad.hs -- module RandomMonad where import Control.Monad import System.Random import Data.List data RandomGen g => Rand g a = Rand (g ->(a,g)) | RandZero instance (Show g, RandomGen g) => Monad (Rand g) where return x = Rand (\g ->(x,g)) (RandZero)>>= _ = RandZero (Rand argTransformer)>>=(parametricRandom) = Rand funTransformer where funTransformer g | isZero x = funTransformer g1 | otherwise = (getRandom x g1,getGen x g1) where x = parametricRandom val (val,g1) = argTransformer g isZero RandZero = True isZero _ = False instance (Show g, RandomGen g) => MonadPlus (Rand g) where mzero = RandZero RandZero `mplus` x = x x `mplus` RandZero = x x `mplus` y = x getRandom :: RandomGen g => Rand g a ->g ->a getRandom (Rand f) g = (fst (f g)) getGen :: RandomGen g => Rand g a ->g -> g getGen (Rand f) g = snd (f g) when I run ghci interpreter, and give following command getRandom y (mkStdGen 2000000000) I can see memory overflow on my computer (1G). It's not expected, and if I delete one guard, it works very fast. Why in this case it works too slow? What I do wrong?

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  • Partially constructed object / Multi threading

    - by reto
    Heya! I'm using joda due to it's good reputation regarding multi threading. It goes great distances to make multi threaded date handling efficient, for example by making all Date/Time/DateTime objects immutable. But here's a situation where I'm not sure if Joda is really doing the right thing. It probably is correct, but I'd be very interested to see the explanation for it. When a toString() of a DateTime is being called Joda does the following: /* org.joda.time.base.AbstractInstant */ public String toString() { return ISODateTimeFormat.dateTime().print(this); } All formatters are thread safe, as they are as well ready-only. But what's about the formatter-factory: private static DateTimeFormatter dt; /* org.joda.time.format.ISODateTimeFormat */ public static DateTimeFormatter dateTime() { if (dt == null) { dt = new DateTimeFormatterBuilder() .append(date()) .append(tTime()) .toFormatter(); } return dt; } This is a common pattern in single threaded applications. I see the following dangers: Race condition during null check -- worst case: two objects get created. No Problem, as this is solely a helper object (unlike a normal singleton pattern situation), one gets saved in dt, the other is lost and will be garbage collected sooner or later. the static variable might point to a partially constructed object before the objec has been finished initialization (before calling me crazy, read about a similar situation in this Wikipedia article. So how does Joda ensure that not partially created formatter gets published in this static variable? Thanks for your explanations! Reto

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  • Why can't I extract a C++ type from a Python type using boost::python::extractor?

    - by Robin
    I've wrapped a C++ class using Py++ and everything is working great in Python. I can instantiate the c++ class, call methods, etc. I'm now trying to embed some Python into a C++ application. This is also working fine for the most-part. I can call functions on a Python module, get return values, etc. The python code I'm calling returns one of the classes that I wrapped: import _myextension as myext def run_script(arg): my_cpp_class = myext.MyClass() return my_cpp_class I'm calling this function from C++ like this: // ... excluding error checking, ref counting, etc. for brevity ... PyObject *pModule, *pFunc, *pArgs, *pReturnValue; Py_Initialize(); pModule = PyImport_Import(PyString_FromString("cpp_interface")); pFunc = PyObject_GetAttrString(pModule, "run_script"); pArgs = PyTuple_New(1); PyTuple_SetItem(pArgs, 0, PyString_FromString("an arg")); pReturnValue = PyObject_CallObject(pFunc, pArgs); bp::extract< MyClass& > extractor(pReturnValue); // PROBLEM IS HERE if (extractor.check()) { // This check is always false MyClass& cls = extractor(); } The problem is the extractor never actually extracts/converts the PyObject* to MyClass (i.e. extractor.check() is always false). According to the docs this is the correct way to extract a wrapped C++ class. I've tried returning basic data types (ints/floats/dicts) from the Python function and all of them are extracted properly. Is there something I'm missing? Is there another way to get the data and cast to MyClass?

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  • Subscribe through API .net C#

    - by Younes
    I have to submit subscription data to another website. I have got documentation on how to use this API however i'm not 100% sure of how to set this up. I do have all the information needed, like username / passwords etc. This is the API documentation: https://www.apiemail.net/api/documentation/?SID=4 How would my request / post / whatever look like in C# .net (vs 2008) when i'm trying to acces this API? This is what i have now, I think i'm not on the right track: public static string GArequestResponseHelper(string url, string token, string username, string password) { HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(url); myRequest.Headers.Add("Username: " + username); myRequest.Headers.Add("Password: " + password); HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse(); Stream responseBody = myResponse.GetResponseStream(); Encoding encode = System.Text.Encoding.GetEncoding("utf-8"); StreamReader readStream = new StreamReader(responseBody, encode); //return string itself (easier to work with) return readStream.ReadToEnd(); Hope someone knows how to set this up properly. Thx!

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  • problem with fork()

    - by john
    I'm writing a shell which forks, with the parent reading the input and the child process parsing and executing it with execvp. pseudocode of main method: do{ pid = fork(); print pid; if (p<0) { error; exit; } if (p>0) { wait for child to finish; read input; } else { call function to parse input; exit; } }while condition return; what happens is that i never seem to enter the child process (pid printed is always positive, i never enter the else). however, if i don't call the parse function and just have else exit, i do correctly enter parent and child alternatingly. full code: int main(int argc, char *argv[]){ char input[500]; pid_t p; int firstrun = 1; do{ p = fork(); printf("PID: %d", p); if (p < 0) {printf("Error forking"); exit(-1);} if (p > 0){ wait(NULL); firstrun = 0; printf("\n> "); bzero(input, 500); fflush(stdout); read(0, input, 499); input[strlen(input)-1] = '\0'; } else exit(0); else { if (parse(input) != 0 && firstrun != 1) { printf("Error parsing"); exit(-1); } exit(0); } }while(strcmp(input, "exit") != 0); return 0; }

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  • Asp MVC - "The Id field is required" validation message on Create; Id not set to [Required]

    - by burnt_hand
    This is happening when I try to create the entity using a Create style action in Asp.Net MVC 2. The POCO has the following properties: public int Id {get;set;} [Required] public string Message {get; set} On the creation of the entity, the Id is set automatically, so there is no need for it on the Create action. The ModelState says that "The Id field is required", but I haven't set that to be so. Is there something automatic going on here? EDIT - Reason Revealed The reason for the issue is answered by Brad Wilson via Paul Speranza in one of the comments below where he says (cheers Paul): You're providing a value for ID, you just didn't know you were. It's in the route data of the default route ("{controller}/{action}/{id}"), and its default value is the empty string, which isn't valid for an int. Use the [Bind] attribute on your action parameter to exclude ID. My default route was: new { controller = "Customer", action = "Edit", id = " " } // Parameter defaults EDIT - Update Model technique I actually changed the way I did this again by using TryUpdateModel and the exclude parameter array asscoiated with that. [HttpPost] public ActionResult Add(Venue collection) { Venue venue = new Venue(); if (TryUpdateModel(venue, null, null, new[] { "Id" })) { _service.Add(venue); return RedirectToAction("Index", "Manage"); } return View(collection); }

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  • Binding update on adds news series to WPF Toolkit chart (instead of replacing/updating series)

    - by Mal Ross
    I'm currently recoding a bar chart in my app to make use of the Chart class in the WPF Toolkit. Using MVVM, I'm binding the ItemsSource of a ColumnSeries in my chart to a property on my viewmodel. Here's the relevant XAML: <charting:Chart> <charting:ColumnSeries ItemsSource="{Binding ScoreDistribution.ClassScores}" IndependentValuePath="ClassName" DependentValuePath="Score"/> </charting:Chart> And the property on the viewmodel: // NB: viewmodel derived from Josh Smith's BindableObject public class ExamResultsViewModel : BindableObject { // ... private ScoreDistributionByClass _scoreDistribution; public ScoreDistributionByClass ScoreDistribution { get { return _scoreDistribution; } set { if (_scoreDistribution == value) { return; } _scoreDistribution = value; RaisePropertyChanged(() => ScoreDistribution); } } However, when I update the ScoreDistribution property (by setting it to a new ScoreDistribution object), the chart gets an additional series (based on the new ScoreDistribution) as well as keeping the original series (based on the previous ScoreDistribution). To illustrate this, here are a couple of screenshots showing the chart before an update (with a single data point in ScoreDistribution.ClassScores) and after it (now with 3 data points in ScoreDistribution.ClassScores): Now, I realise there are other ways I could be doing this (e.g. changing the contents of the original ScoreDistribution object rather than replacing it entirely), but I don't understand why it's going wrong in its current form. Can anyone help?

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  • PHP Form Validation

    - by JM4
    This question will undoubtedly be difficult to answer and ask in a way that makes sense but I'll try my best: I have a form which uses PHP to display certain sections of the form such as: <?php if ($_SESSION['EnrType'] == "Individual") { display only form information for individual enrollment } ?> and <?php if ($_SESSION['Num_Enrs'] > 6) { display only form information for 7 total members enrollment } ?> In each form piece, unique information is collected about each enrollee but the basic criteria for each enrollee is the same, i.e. All enrollee's must use have a value in the FirstName field. Each field is named according to the enrollee number, i.e. Num1FirstName; Num2FirstName. I have a PHP validation script which is absolutely fantastic and am not looking to change it but the issue I am running into is duplication of the script in order to validate ALL fields in one swoop. On submission, all POSTED items are run through my validation script and based on the rules set return an error if they do not equal true. Sample code: if (isset($_POST['submit'])) { // import the validation library require("validation.php"); $rules = array(); // stores the validation rules //All Enrollee Rules $rules[] = "required,Num1FirstName,Num2FirstName,The First Name field is required."; The script above does the following, $rules[] ="REQUIREMENT,fieldname,error message" where requirement gives criteria (in this case, simply that a value is passed), fieldname is the name of the field being validated, and error message returns the error used. My Goal is to use the same formula above and have $rules[] run through ALL firstnames and return the error posted ONLY if they exist (i.e. dont check for member #7's first name if it doesnt exist on the screen). If I simply put a comma between the 'fieldnames' this only checks for the first, then second, and so on so this wont work. Any ideas?

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  • Field Members vs Method Variables?

    - by Braveyard
    Recently I've been thinking about performance difference between class field members and method variables. What exactly I mean is in the example below : Lets say we have a DataContext object for Linq2SQL class DataLayer { ProductDataContext context = new ProductDataContext(); public IQueryable<Product> GetData() { return context.Where(t=>t.ProductId == 2); } } In the example above, context will be stored in heap and the GetData method variables will be removed from Stack after Method is executed. So lets examine the following example to make a distinction : class DataLayer { public IQueryable<Product> GetData() { ProductDataContext context = new ProductDataContext(); return context.Where(t=>t.ProductId == 2); } } (*1) So okay first thing we know is if we define ProductDataContext instance as a field, we can reach it everywhere in the class which means we don't have to create same object instance all the time. But lets say we are talking about Asp.NET and once the users press submit button the post data is sent to the server and the events are executed and the posted data stored in a database via the method above so it is probable that the same user can send different data after one another.If I know correctly after the page is executed, the finalizers come into play and clear things from memory (from heap) and that means we lose our instance variables from memory as well and after another post, DataContext should be created once again for the new page cycle. So it seems the only benefit of declaring it publicly to the whole class is the just number one text above. Or is there something other? Thanks in advance... (If I told something incorrect please fix me.. )

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  • stackoverflow tags and related tags

    - by parminder
    Hi Experts, I am working on a website where a user can add tags to their posted books. It is similar to stackover flow, but I am keeping my tags in differnt table. so here are the tables/class in linq to entities. Books { bookId, Title } Tags { Id Tag } BooksTags { Id BookId TagId } Here are few sample records. Books BookId Title 113421 A 113422 B Tags Id Tag 1 ASP 2 C# 3 CSS 4 VB 5 VB.NET 6 PHP 7 java 8 pascal BooksTags Id BookId TagId 1 113421 1 2 113421 2 3 113421 3 4 113421 4 5 113422 1 6 113422 4 7 113422 8 Question 1 : I need to write something in linq to entities queries which gives me data according to the tags say if I want bookIds where tagid =1 it should return bookid 113421 and 113422 as it exists in both the books, but If I ask data for tags 1 and 2 it should return only book 113421 as that is the only book where both the tags are present. Question 2 : I need tags and their count too to show in related tags, so in first case my related tags class should have following result. RelatedTags Tag Count 2 1 3 1 4 2 8 1 in the second case when two tags are requested the result should be like RelatedTags Tag Count 3 1 4 1 I have get the first thing working by converting a sql query in linqer, but that seems like a hell. so want to know if there is any better idea. I have used dyanmic where clause to include two tags. So if someone can help. It will be much appreciated. Thanks Parminder

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  • Java HashSet using a specified method

    - by threenplusone
    I have a basic class 'HistoryItem' like so: public class HistoryItem private Date startDate; private Date endDate; private Info info; private String details; @Override public int hashCode() { int hash = (startDate == null ? 0 : startDate.hashCode()); hash = hash * 31 + (endDate == null ? 0 : endDate.hashCode()); return hash; } } I am currently using a HashSet to remove duplicates from an ArrayList on the startDate & endDate fields, which is working correctly. However I also need to remove duplicates on different fields (info & details). My question is this. Is there a way to specify a different method which HashSet will use in place of hashCode()? Something like this: public int hashCode_2() { int hash = (info == null ? 0 : info.hashCode()); hash = hash * 31 + (details == null ? 0 : details.hashCode()); return hash; } Set<HistoryItem> removeDups = new HashSet<HistoryItem>(); removeDups.setHashMethod(hashCode_2); Or is there another way that I should be doing this?

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