Search Results

Search found 5157 results on 207 pages for 'logic gates'.

Page 173/207 | < Previous Page | 169 170 171 172 173 174 175 176 177 178 179 180  | Next Page >

  • Meteor: how to update DOM via Javascript without a page refresh?

    - by strack
    UPDATE: It looks like this script may be the catalyst I'm looking for. Will test it and answer/close this question if so. I'm sure I'll find the answer to this eventually, but I'm putting it out there now, in case someone else knows it right off... I am using RaphaelJS to manipulate the DOM (adds a bunch of SVG tags to an identified DIV), and I want to re-render those specific DOM parts, if there's an update to the MongoDB collection. As an example: -Let's say that I have a collection called PiePieces. -When the page is first rendered/ called, let's pretend that the number of pieces in the collection is 4. -I programmatically add a pie piece using console: PiePieces.insert({...}) -I want the page to update like it would for a standard handlebars binding situation, but the problem is, the new entry needs to go through the Raphael script, which performs direct DOM manipulation. So, the logic would go something like this: MongoDB collection update event - Client function call to manipulate DOM - DOM modified/ page updated without a refresh. I've tried implementing this by reading values from the DOM itself, and I can get the updated DOM, but the entire page refreshes and/or I have to manually refresh the page, OR the DOM tree isn't completed yet, and so it's blank until I refresh. Can you point me in the right direction, maybe with a small code snippet/example? (if something similar already exists, just tell me where and I'll go digging) Thanks in advance! (I am LOVING Meteor so far...)

    Read the article

  • Android OpenGL es "glDrawTexfOES" draws upside down

    - by Alle
    I'm using OpenGL for Android to draw my 2D images. Whenever I draw something using the code: gl.glViewport(aspectRatioOffset, 0, screenWidth, screenHeight); gl.glMatrixMode(GL10.GL_PROJECTION); gl.glLoadIdentity(); GLU.gluOrtho2D(gl, aspectRatioOffset, screenWidth + aspectRatioOffset,screenHeight, 0); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glEnable(GL10.GL_TEXTURE_2D); gl.glBindTexture(GL10.GL_TEXTURE_2D, myScene.neededGraphics.get(ID).get(animationID).get(animationIndex)); crop[0] = 0; crop[1] = 0; crop[2] = width; crop[3] = height; ((GL11Ext)gl).glDrawTexfOES(x, y, z, width, height) I get an upside down result. I'v seen people solve this through doing: crop[0] = 0; crop[1] = height; crop[2] = width; crop[3] = -height; This does however hurt the logic in my application, so I would like the result to not be flipped upside down. Does anyone know why it happen, and any way of avoiding or solving it?

    Read the article

  • Why is a DataViewManager not sorting?

    - by Alarion
    First off, a quick rundown of what the code is doing. I have two tables: Companies and Clients. There is a one to many relationship between Companies and Clients (one company can have many clients). In some processing logic, I have both tables loaded into a DataSet - each are DataTables. I have added a DataRelation to set the relationship, and it works when I use GetChildRows on a record from the Companies table. However, I need to sort the records returned. After googling around some it looks like the DataViewManager is the way to go, and I have examined several basic examples. However, I cannot get my rows sorted. Am I missing something, or am I not using this how it is supposed to be used? Example code: Dim ldvmManager As New DataViewManager(mdsData) ldvmManager.DataViewSettings("Companies").Sort = "comName ASC" ldvmManager.DataViewSettings("Clients").ApplyDefaultSort = False ldvmManager.DataViewSettings("Clients").Sort = "entLastName ASC, entFirstName ASC" For Each mdrCurrentCompany in ldvmManager.DataViewSettings("Companies").Table.Rows Dim ldrClients() as DataRow = mdrCurrentCompany.GetChildRows("CompaniesClients") Next No matter what I do, the first Client returned has a last name that starts with a 'B' and the second has one that starts with a 'A'. From there, the order is all mixed up. If I use my entire data instead of the subset I was using to test with, the first Client returned has a last name that starts with 'J'. It seems like it is still using whatever default sort was being used before I tried to use the DataViewManager. Any ideas?

    Read the article

  • Representing versions of objects with CakePHP

    - by user636901
    Hi people, Have just started to get into CakePHP since a couple of weeks back. I have some experience with MVC-frameworks, but this problem holds me back a bit. I am currently working on a model foo, containing a primary id and some attributes. Since a complete history of the changes of foo is necessary, the content of foo is saved in the table foo_content. The two tables are connected through foo_content.foo_id = foo.id, in Cake with a foo hasMany foo_content-relationship. To track the versions of foo, foo_content also contains the column version, and foo itself the field currentVersion. The version is an number incremented by one everytime the user updates foo. This is an older native PHP-app btw, to be rewritten on top of Cake. 9 times out of 10 in the app, the most recent version (foo.currentVersion) is the db-entry that need to be represented in the frontend. My question is simply: is there someway of representing this directly in the model? Or does this kind of logic simply need to be defined in the controller? Most grateful for your help!

    Read the article

  • PHP: Three item validation comparison

    - by DavidYell
    I have 3 featured product panels on the homepage, and I'm writing a CMS page for it. I'm trying to validate the items. They are selected via three <select> elements, featured1, featured2 and featured3. The default is <option value="0" selected>Select an element</option> I need to validate the $_POST to ensure that the user hasn't selected the same product for more than one of the panels. I have worked out that each $_POST needs to be $_POST['featuredN'] > 0 but I can't seem to find a logical way of processing the 7 potential outcomes. Using a logic table, where 1 is a set value. 1 2 3 ------- 0 0 0 1 1 1 1 0 0 0 1 0 0 0 1 1 1 0 0 1 1 If an item is 0, then I will not update it, but I want the user to be able to update a single item if needs be. I cannot find a logical way to see if the item is not 0, and then compare it to another item if that also is not 0. So far my colleague suggested, adding up the values. Which works to see if condition 1 0 0 0 is not met. I have a vague feeling that some form of recursive function might be in order, but I can't quite get my brain to help me on this one! So to the collective brain! :)

    Read the article

  • Javascript code refactoring and assessment

    - by neitony
    I'm using javascript to toggle the display state of some objects based on the time of day. A sample of the code is given below. I was wondering if anyone could give a suggestion as to how I can refactor this code while at the same time improving the logic. switch(tcode) { case 'eur' : eur.setAttribute('style', 'display:block; opacity:0.5'); us.style.display = 'none'; asia.style.display = 'none'; us_inactive.style.display = 'block'; asia_inactive.style.display = 'block'; break; case 'us' : us.style.display = 'block'; eur.style.display = 'none'; asia.style.display = 'none'; eur_inactive.style.display = 'block'; asia_inactive.style.display = 'block'; break; case 'asia' : asia.setAttribute('style', 'display:block; opacity:0.5'); us.style.display = 'none'; eur.style.display = 'none'; eur_inactive.style.display = 'block'; us_inactive.style.display = 'block';

    Read the article

  • perl system command return code

    - by Mel
    I have a script that has been running for over a year and now it is failing: It is creating a command file: open ( FTPFILE, ">get_list"); print FTPFILE "dir *.txt"\n"; print FTPFILE "quit\n"; close FTPFILE; Then I run the system command: $command = "ftp ".$Server." < get_list | grep \"\^-\" >new_list"; $code = system($command); The logic the checks: if ($code == 0) { do stuff } else { log error } It is logging an error. When I print the $code variable, I am getting 256. I used this command to parse the $? variable: $exit_value = $? >> 8; $signal_num = $? & 127; $dumped_core = $? & 128; print "Exit: $exit_value Sig: $signal_num Core: $dumped_core\n"; Results: Exit: 1 Sig: 0 Core: 0 Thanks for any help/insight.

    Read the article

  • Java Detect Variable Change Using PropertyChangeSupport and PropertyChangeListener

    - by Sam
    I'm trying to print out debug statements when some third party code changes a variable. For example, consider the following: public final class MysteryClass { private int secretCounter; public synchronized int getCounter() { return secretCounter; } public synchronized void incrementCounter() { secretCounter++; } } public class MyClass { public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // add code here to detect calls to incrementCounter and print a debug message } I don't have the ability to change the 3rd party MysteryClass, so I thought that I could use PropertyChangeSupport and PropertyChangeListener to detect changes to the secretCounter: public class MyClass implements PropertyChangeListener { private PropertyChangeSupport propertySupport = new PropertyChangeSupport(this); public MyClass() { propertySupport.addPropertyChangeListener(this); } public void propertyChange(PropertyChangeEvent evt) { System.out.println("property changing: " + evt.getPropertyName()); } public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // do logic which involves increment and getting the value of MysteryClass } } Unfortunately, this did not work and I have no debug messages printed out. Does anyone see what is wrong with my implementation of the PropertyChangeSupport and Listener interfaces? I want to print a debug statement whenever incrementCounter is called or the value of secretCounter changes.

    Read the article

  • Should I *always* import my file references into the database in drupal?

    - by sprugman
    I have a cck type with an image field, and a unique_id text field. The file name of the image is based on the unique_id. All of the content, including the image itself is being generated automatically via another process, and I'm parsing what that generates into nodes. Rather than creating separate fields for the id and the image, and doing an official import of the image into the files table, I'm tempted to only create the id field and create the file reference in the theme layer. I can think of pros and cons: 1) Theme Layer Approach Pros: makes the import process much less complex don't have to worry about syncing the db with the file system as things change more flexible -- I can move my images around more easily if I want Cons: maybe not as much The Drupal Way™ not as pure -- I'll wind up with more logic on the theme side. 2) Import Approach Pros: import method is required if we ever wanted to make the files private (we won't.) safer? Maybe I'll know if there's a problem with the image at import time, rather than view time. Since I'll be bulk importing, that might make a difference. if I delete a node through the admin interface, drupal might be able to delete the file for me, as well. Con: more complex import and maintenance All else being equal, simpler is always better, so I'm leaning toward #1. Are there any other issues I'm missing? (Since this is an open ended question, I guess I'll make it a community wiki, whatever that means.)

    Read the article

  • What is a good use case for static import of methods?

    - by Miserable Variable
    Just got a review comment that my static import of the method was not a good idea. The static import was of a method from a DA class, which has mostly static methods. So in middle of the business logic I had a da activity that apparently seemed to belong to the current class: import static some.package.DA.*; class BusinessObject { void someMethod() { .... save(this); } } The reviewer was not keen that I change the code and I didn't but I do kind of agree with him. One reason given for not static-importing was it was confusing where the method was defined, it wasn't in the current class and not in any superclass so it too some time to identify its definition (the web based review system does not have clickable links like IDE :-) I don't really think this matters, static-imports are still quite new and soon we will all get used to locating them. But the other reason, the one I agree with, is that an unqualified method call seems to belong to current object and should not jump contexts. But if it really did belong, it would make sense to extend that super class. So, when does it make sense to static import methods? When have you done it? Did/do you like the way the unqualified calls look? EDIT: The popular opinion seems to be that static-import methods if nobody is going to confuse them as methods of the current class. For example methods from java.lang.Math and java.awt.Color. But if abs and getAlpha are not ambiguous I don't see why readEmployee is. As in lot of programming choices, I think this too is a personal preference thing. Thanks for your response guys, I am closing the question.

    Read the article

  • How to use App.Xaml's ResourseDictionaries with own entry point

    - by Polaris
    Hello friends. I created some logic for singleInstance application and I must to use my own entry point (not App.xaml) for Application. I have some styles in App.xaml which now is not working. How can I use this ResourceDictionaries from my App.xaml for entire project in my situation? My class for manage Application Startup public class SingleInstanceManager : WindowsFormsApplicationBase { App app; public SingleInstanceManager() { this.IsSingleInstance = true; } protected override bool OnStartup(Microsoft.VisualBasic.ApplicationServices.StartupEventArgs e) { try { // First time app is launched app = new App(); App.Current.Properties["rcID"] = e.CommandLine; //IntroLibrary.OpenDocumentFromNotify(); app.Run(); return false; } catch (Exception ex) { MessageBox.Show(ex.Message); return false; } } protected override void OnStartupNextInstance(StartupNextInstanceEventArgs eventArgs) { // Subsequent launches base.OnStartupNextInstance(eventArgs); Intro win = (Intro)app.MainWindow; if (eventArgs != null) { App.Current.Properties["rcID"] = eventArgs.CommandLine[0]; } IntroLibrary.OpenDocumentFromNotify(); app.Activate(); } } and my own Entry Point: public class EntryPoint { [STAThread] public static void Main(string[] args) { SingleInstanceManager manager = new SingleInstanceManager(); manager.Run(args); } } And my App.Xaml code behind: public partial class App : Application { protected override void OnStartup(System.Windows.StartupEventArgs e) { base.OnStartup(e); // Create and show the application's main window Intro window = new Intro(); window.Show(); } public void Activate() { // Reactivate application's main window this.MainWindow.Activate(); } } And my App.xaml has some code which decribe ResourceDictionaries which doesnt work. Why?

    Read the article

  • Wicket: Where to add components? Constructor? Or onBeforeRender?

    - by gmallett
    I'm a Wicket newb. This may just be my ignorance of the Wicket lifecycle so please enlighten me! My understanding is that Wicket WebPage objects are instantiated once and then serialized. This has led to a point of confusion for me, see below. Currently I have a template class which I intend to subclass. I followed the example in the Wicket docs demonstrating how to override the template's behavior in the subclass: protected void onBeforeRender() { add(new Label("title", getTitle())); super.onBeforeRender(); } protected String getTitle() { return "template"; } Subclass: protected String getTitle() { return "Home"; } This works very well. What's not clear to me are the "best practices" for this. It seems like onBeforeRender() is called on every request for the page, no? This seems like there would be substantially more processing done on a page if everything is in onBeforeRender(). I could easily follow the example of the other Wicket examples and add some components in the constructor that I do not want to override, but then I've divided by component logic into two places, something I'm hesitant to do. If I add a component that I intend to be in all subclasses, should I add it to the constructor or onBeforeRender()?

    Read the article

  • Symfony form->bind fails

    - by Shawn Craver
    I'm working with a few custom forms, and one of them isn't binding it's values on a POST. I'm using the same logic for each, and only one of them isn't working. Here's the code: public function executeMediaFileUpload(sfWebRequest $request) { $this->form = new MediaFileUploadForm(); if (!$request->isMethod('POST')) $psk = $request->getParameter('psk'); else { $this->form->bind($request->getParameter($this->form->getName()), $request->getFiles($this->form->getName())); $this->logMessage('VALUE: ' . $this->form->getValue('version')); $psk = $this->form->getValue('application'); } $this->logMessage('PSK: ' . $psk); $app = Doctrine::getTable('Application')->find(array($psk)); $this->form->setDefault('application', $app->getPsk()); $this->form->setDefault('version', $app->getVersion()->getLast()->getPsk()); On the initial GET, I can see the value passed in via psk getting set as the default for application in the generated HTML, and all the values show up in the POST request in Firebug, but after I bind the form, it still contains no values.

    Read the article

  • escape exactly what in javascript

    - by Emin
    Hi all, Being a newbie in javascript I came to a situation where I need more information on escaping characters in a string. Basically I know that in order to escape " I need to replace it with \" but what I don't know is for which characters I need to escape a particular string for. Is there a list of these "characters to escape"? or is it any character that is not a-zA-Z0-9 ? In my situation, I don't have control over the content that is being displayed on my page. Users enter some text and save it. I then use a webservice to extract them from the database, build a json array of objects, then iterate the array when I need to display them. In this case, I have - naturally - no idea of what the text the user has entered and therefore for what characters I need to escape. I also use jQuery for this specific project (just in case it has a function I am not aware of, to do what I need) Providing examples would be appreciated but I also want to learn the theory and logic behind it. Hope someone can be of any help.

    Read the article

  • Dependencyproperty doesn't have value on load

    - by Jakob
    My problem is this, I have a UC called profile that contains another UC called FollowImageControl. In my Profile.xaml i declaretively bind a property of FollowImageControl called FollowerId to a CurrentUserId from Profile.xaml.cs. Problem is that I CurrentUserId is assigned in Profile.xaml.cs; the Profile.xaml code-behind. This means that I do not initially get the FollowerId. I have these methods in the FollowImageControl.xaml.cs: public static readonly DependencyProperty _followUserId = DependencyProperty.Register("FollowUserId", typeof(Guid), typeof(FollowImageControl), null); public Guid FollowUserId { get { return (Guid)GetValue(_followUserId); } set { SetValue(_followUserId, value); } } public FollowImageControl() { // Required to initialize variables InitializeComponent(); LoggedInUserId = WebContext.Current.User.UserId; var ctx = new NotesDomainContext(); if (ctx.IsFollowingUser(LoggedInUserId, FollowUserId).Value) SwitchToDelete.Begin(); } private void AddImg_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { if (LoggedInUserId != FollowUserId) { var ctx = new NotesDomainContext(); ctx.FollowUser(FollowUserId, LoggedInUserId); ctx.SubmitChanges(); } } THE WEIRD THING IS that when i insert breakpoints the FollowerUserId in FollowImageControl() is 0, but it has a value in AddImg_MouseLeftButtonDown, and there is no inbetween logic that sets the value of it. How is this??? Here's a little more code info: This is my binding from profile.xaml <internalCtrl:FollowImageControl FollowUserId="{Binding ElementName=ProfileCtrl, Path=CurrentUserId}" /> this is my constructor in profile.xaml.cs wherein the CurrentUserId is set public static readonly DependencyProperty _CurrentUserId = DependencyProperty.Register("CurrentUserId", typeof(Guid), typeof(Profile), null); public Guid CurrentUserId { get { return (Guid)GetValue(_CurrentUserId); } set { SetValue(_CurrentUserId, value); } } public Profile(Guid UserId) { CurrentUserId = UserId; InitializeComponent(); Loaded += new RoutedEventHandler(Profile_Loaded); } I'm seriously dumbfound that one minute the FollowerId has no value, and the next it holds the right, without me having changed the value in the code-behind.

    Read the article

  • What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

    - by dcuccia
    I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

    Read the article

  • Setup for games animation: How do I know JFrame is finished setting itself up?

    - by Jokkel
    I'm using javax.swing.JFrame to draw game animations using double buffer strategy. First, I set up the frame. JFrame frame = new JFrame(); frame.setVisible(true); Now, I draw an object (let it be a circle, doesn't matter) like this. frame.createBufferStrategy(2); bufferStrategy = frame.getBufferStrategy(); Graphics g = bufferStrategy.getDrawGraphics(); circle.draw(g); bufferStrategy.show(); The problem is that the frame is not always fully set-up when the drawing takes place. Seems like JFrame needs up to three steps in resizing itself, until it reaches it's final size. That makes the drawing slide out of frame or hinders it to appear completely from time to time. I already managed to delay things using SwingUtilities.invokeLater(). While this improved the result, there are still times when the drawing slides away / looks prematurely draw. Any idea / strategy? Thanks in advance. EDIT: Ok thanks so far. I didn't mention that I write a little Pong game in the first place. Sorry for the confusion What I actually looked for was the right setup for accelerated game animations done in Java. While reading through the suggestions I found my question answered (though indirectly) here and this example made things clear for me. A resume for this might be that for animating game graphics in Java, the first step is to get rid of the GUI logic overhead.

    Read the article

  • How to end a thread in perl

    - by user1672190
    I am new to perl and i have a question about perl thread. I am trying to create a new thread to check if the running function is timed out, and my way of doing it is as below. Logic is 1.create a new thread 2.run the main function and see if it is timed out, if ture, kill it Sample code: $exit_tread = false; # a flag to make sure timeout thread will run my $thr_timeout = threads->new( \&timeout ); execute main function here; $exit_thread = true # set the flag to true to force thread ends $thr_timeout->join(); #wait for the timeout thread ends Code of timeout function sub timeout { $timeout = false; my $start_time = time(); while (!$exit_thread) { sleep(1); last if (main function is executed); if (time() - $start_time >= configured time ) { logmsg "process is killed as request timed out"; _kill_remote_process(); $timeout = true; last; } } } now the code is running as i expected, but i am just not very clear if the code $exit_thread = true works because there is a "last" at the end of while loop. Can anybody give me a answer? Thanks

    Read the article

  • Typical Search, Result and Detail Workflow Staying Within an Android Tab

    - by Justin
    So, I've been banging my head looking for a good solution for a few days and am stuck. I have a search screen (Activity) in a tab, and after the user enters a value and clicks "search" I would like the results to come back in that same tab, and then if an item from the results is selected, to show more detailed results, in that same tab. I have it all working now in separate activities, and even the first step working in a tab, but as soon as I call the activity to process he search results... i.e. startActivity(i); for the results Activity, the results displayed are not in the tab! I am having a very difficult time getting this flow to work all under a tab. Any thoughts on how to make this happen? I keep hearing that Android views should be used instead of activities, but am I then to assume that all the logic I have right now for 3 activity needs to go inside 1 activity and then I need to handle setting the content and state for each of these cases? Plus, won't the history stack not work as pressing the back button will take the user out of the application, instead of taking them from say the search result to the search screen, or the details to the search results, etc. This seems like a mess. Can anyone show a more complex example of tabs or how one might have a simple search, result and detail workflow staying in a tab? I have seen a few questions on this concept of keeping activities "within a tab", but no good resolution. Please help.

    Read the article

  • Ordering .each results in the view...

    - by bgadoci
    I am wondering if it is possible to dictate the order (i.e. :order = 'created_at DESC') within the view. I realize that logic in the view is not ideal but I seem to be having some problems locating where to affect this output. For instance, here is my code: <% @user.questions.each do |question| %> <%= link_to_unless_current h (question.title), question %> Created about <%= time_ago_in_words h(question.created_at) %> ago Updated about <%= time_ago_in_words h(question.updated_at) %> ago <%= link_to 'Edit', edit_question_path(question) %> | <%= link_to 'Destroy', question, :confirm => 'Are you sure?', :method => :delete %> <% end %> In my QuestionsController I have the following index action but it is not affecting the output from the code above. class QuestionsController < ApplicationController def index @questions = Question.all(:order => 'created_at DESC', :limit => 20) respond_to do |format| format.html # index.html.erb format.xml { render :xml => @questions } end end end

    Read the article

  • How to add clear option to this whiteboard?

    - by swift
    i have to add clear screen option to my whiteboard application, usual procedure is to draw a fill rect to the sizeof the image. But in my app i have transparent panels added one above the other i.e as layers, if i follow the usual procedure the drawing from the underlying panel wont be visible. please tell me any logic to do this. public void createFrame() { JFrame frame = new JFrame(); JLayeredPane layerpane=frame.getLayeredPane(); board= new Whiteboard(client); //board is a transparent panel // tranparent image: board.image = new BufferedImage(590,690, BufferedImage.TYPE_INT_ARGB); board.setBounds(74,23,590,690); board.setImage(image); virtualboard.setImage(image); //virtualboardboard is a transparent panel virtualboard.setBounds(74,23,590,690); JPanel background=new JPanel(); background.setBackground(Color.white); background.setBounds(74,25,590,685); layerpane.add(board,new Integer(5)); layerpane.add(virtualboard,new Integer(4));//Panel where remote user draws layerpane.add(background,new Integer(3)); layerpane.add(board.colourButtons(),new Integer(2)); layerpane.add(board.shapeButtons(),new Integer(1)); layerpane.add(board.createEmptyPanel(),new Integer(0)); }

    Read the article

  • Parallelizing L2S Entity Retrieval

    - by MarkB
    Assuming a typical domain entity approach with SQL Server and a dbml/L2S DAL with a logic layer on top of that: In situations where lazy loading is not an option, I have settled on a convention where getting a list of entities does not also get each item's child entities (no loading), but getting a single entity does (eager loading). Since getting a single entity also gets children, it causes a cascading effect in which each child then gets its children too. This sounds bad, but as long as the model is not too deep, I usually don't see performance problems that outweigh the benefits of the ease of use. So if I want to get a list in which each of the items is fully hydrated with children, I combine the GetList and GetItem methods. So I'll get a list and then loop through it getting each item with the full cascade. Even this is generally acceptable in many of the projects I've worked on - but I have recently encountered situations with larger models and/or more data in which it needs to be more efficient. I've found that partitioning the loop and executing it on multiple threads yields excellent results. In my first experiment with a list of 50 items from one particular project, I did 5 threads of 10 items each and got a 3X improvement in time. Of course, the mileage will vary depending on the project but all else being equal this is clearly a big opportunity. However, before I go further, I was wondering what others have done that have already been through this. What are some good approaches to parallelizing this type of thing?

    Read the article

  • Deleting unneeded rows from a table with 2 criteria

    - by stormbreaker
    Hello. I have a many-to-many relations table and I need to DELETE the unneeded rows. The lastviews table's structure is: | user (int) | document (int) | time (datetime) | This table logs the last users which viewed the document. (user, document) is unique. I show only the last 10 views of a document and until now I deleted the unneeded like this: DELETE FROM `lastviews` WHERE `document` = ? AND `user` NOT IN (SELECT * FROM (SELECT `user` FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10) AS TAB) However, now I need to also show the last 5 documents a user has viewed. This means I can no longer delete rows using the previous query because it might delete information I need (say a user didn't view documents in 5 minutes and the rows are deleted) To sum up, I need to delete all the records that don't fit these 2 criterias: SELECT ... FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10 and SELECT * FROM `lastviews` WHERE `user` = ? ORDER BY `time` DESC LIMIT 0, 5 I need the logic. Thanks in advance.

    Read the article

  • .NET 4 ... Parallel.ForEach() question

    - by CirrusFlyer
    I understand that the new TPL (Task Parallel Library) has implemented the Parallel.ForEach() such that it works with "expressed parallelism." Meaning, it does not guarantee that your delegates will run in multiple threads, but rather it checks to see if the host platform has multiple cores, and if true, only then does it distribute the work across the cores (essentially 1 thread per core). If the host system does not have multiple cores (getting harder and harder to find such a computer) then it will run your code sequenceally like a "regular" foreach loop would. Pretty cool stuff, frankly. Normally I would do something like the following to place my long running operation on a background thread from the ThreadPool: ThreadPool.QueueUserWorkItem( new WaitCallback(targetMethod), new Object2PassIn() ); In a situation whereby the host computer only has a single core does the TPL's Parallel.ForEach() automatically place the invocation on a background thread? Or, should I manaully invoke any TPL calls from a background thead so that if I am executing from a single core computer at least that logic will be off of the GUI's dispatching thread? My concern is if I leave the TPL in charge of all this I want to ensure if it determines it's a single core box that it still marshalls the code that's inside of the Parallel.ForEach() loop on to a background thread like I would have done, so as to not block my GUI. Thanks for any thoughts or advice you may have ...

    Read the article

  • Many tables for many users?

    - by Seagull
    I am new to web programming, so excuse the ignorance... ;-) I have a web application that in many ways can be considered to be a multi-tenant environment. By this I mean that each user of the application gets their own 'custom' environment, with absolutely no interaction between those users. So far I have built the web application as a 'single user' environment. In other words, I haven't actually done anything to support multi-users, but only worked on the functionality I want from the app. Here is my problem... What's the best way to build a multi-user environment: All users point to the same 'core' backend. In other words, I build the logic to separate users via appropriate SQL queries (eg. select * from table where user='123' and attribute='456'). Each user points to a unique tablespace, which is built separately as they join the system. In this case I would simply generate ALL the relevant SQL tables per user, with some sort of suffix for the user. (eg. now a query would look like 'select * from table_ where attribute ='456'). In short, it's a difference between "select * from table where USER=" and "select * from table_USER".

    Read the article

< Previous Page | 169 170 171 172 173 174 175 176 177 178 179 180  | Next Page >