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  • Error in Ordinary Differential Equation representation

    - by Priya M
    UPDATE I am trying to find the Lyapunov Exponents given in link LE. I am trying to figure it out and understand it by taking the following eqs for my case. These are a set of ordinary differential equations (these are just for testing how to work with cos and sin as ODE) f(1)=ALPHA*(y-x); f(2)=x*(R-z)-y; f(3) = 10*cos(x); and x=X(1); y=X(2); cos(y)=X(3); f1 means dx/dt;f2 dy/dt and f3 in this case would be -10sinx. However,when expressing as x=X(1);y=X(2);i am unsure how to express for cos.This is just a trial example i was doing so as to know how to work with equations where we have a cos,sin etc terms as a function of another variable. When using ode45 to solve these Eqs [T,Res]=sol(3,@test_eq,@ode45,0,0.01,20,[7 2 100 ],10); it throws the following error ??? Attempted to access (2); index must be a positive integer or logical. Error in ==> Eq at 19 x=X(1); y=X(2); cos(x)=X(3); Is my representation x=X(1); y=X(2); cos(y)=X(3); alright? How to resolve the error? Thank you

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  • ASP.NET MVC 2.0 + Implementation of a IRouteHandler goes not fire

    - by Peter
    Can anybody please help me with this as I have no idea why public IHttpHandler GetHttpHandler(RequestContext requestContext) is not executing. In my Global.asax.cs I have public class MvcApplication : System.Web.HttpApplication { public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = "" } // Parameter defaults ); routes.Add("ImageRoutes", new Route("Images/{filename}", new CustomRouteHandler())); } protected void Application_Start() { RegisterRoutes(RouteTable.Routes); } } //CustomRouteHandler implementation is below public class CustomRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { // IF I SET A BREAK POINT HERE IT DOES NOT HIT FOR SOME REASON. string filename = requestContext.RouteData.Values["filename"] as string; if (string.IsNullOrEmpty(filename)) { // return a 404 HttpHandler here } else { requestContext.HttpContext.Response.Clear(); requestContext.HttpContext.Response.ContentType = GetContentType(requestContext.HttpContext.Request.Url.ToString()); // find physical path to image here. string filepath = requestContext.HttpContext.Server.MapPath("~/logo.jpg"); requestContext.HttpContext.Response.WriteFile(filepath); requestContext.HttpContext.Response.End(); } return null; } } Can any body tell me what I'm missing here. Simply public IHttpHandler GetHttpHandler(RequestContext requestContext) does not fire. I havn't change anything in the web.config either. What I'm missing here? Please help.

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  • A GUID as the MySQL table's Primary Key or as a separate column

    - by Ben
    I have a multi-process program that performs, in a 2 hour period, 5-10 million inserts to a 34GB table within a single Master/Slave MySQL setup (plus an equal number of reads in that period). The table in question has only 5 fields and 3 (single field) indexes. The primary key is auto-incrementing. I am far from a DBA, but the database appears to be crippled during this two hour period. So, I have a couple of general questions. 1) How much bang will I get out of batching these writes into units of 10? Currently, I am writing each insert serially because, after writing, I immediately need to know, in my program, the resulting primary key of each insert. The PK is the only unique field presently and approximating the order of insertion with something like a Datetime field or a multi-column value is not acceptable. If I perform a bulk insert, I won't know these IDs, which is a problem. So, I've been thinking about turning the auto-increment primary key into a GUID and enforcing uniqueness. I've also been kicking around the idea of creating a new column just for the purposes of the GUID. I don't really see the what that achieves though, that the PK approach doesn't already offer. As far as I can tell, the big downside to making the PK a randomly generated number is that the index would take a long time to update on each insert (since insertion order would not be sequential). Is that an acceptable approach for a table that is taking this number of writes? Thanks, Ben

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  • How to set App as site.com/ in Kohana3

    - by Drew
    Hi all! I've only just started using Kohana ( 3 hours ago), and so far it's blown my socks off (and I'm wearing slippers, so that's quite impressive). Right now, I have a controller 'Controller_FrontPage' with associated views and models and I'm trying to get it accesible from the root of my website (eg, http://www.mysite.com/). If I edit the default controller in the bootstrap from: Route::set('default', '(<controller>(/<action>(/<id>)))') ->defaults(array( 'controller' => 'welcome', 'action' => 'index', )); to 'controller' => '', I get an error, could not find controller_ (which makes sense), and if I change it to 'controller' => '/', I get an error, could not find controller_/ (which also makes sense). If I set 'controller' => 'FrontPage', everything works fine, but all my links (html::anchor(...)) point to http://www.mysite.com/FrontPage/*. Is there a way to have all the anchors point to http://www.mysite.com/*?

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  • odd nullreference error at foreach when rendering view

    - by giddy
    This error is so weird I Just can't really figure out what is really wrong! In UserController I have public virtual ActionResult Index() { var usersmdl = from u in RepositoryFactory.GetUserRepo().GetAll() select new UserViewModel { ID = u.ID, UserName = u.Username, UserGroupName = u.UserGroupMain.GroupName, BranchName = u.Branch.BranchName, Password = u.Password, Ace = u.ACE, CIF = u.CIF, PF = u.PF }; if (usersmdl != null) { return View(usersmdl.AsEnumerable()); } return View(); } My view is of type @model IEnumerable<UserViewModel> on the top. This is what happens: Where and what exactly IS null!? I create the users from a fake repository with moq. I also wrote unit tests, which pass, to ensure the right amount of mocked users are returned. Maybe someone can point me in the right direction here? Top of the stack trace is : at lambda_method(Closure , User ) at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext() at ASP.Index_cshtml.Execute() Is it something to do with linq here? Tell me If I should include the full stack trace.

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  • Can the Subversion client (svn) derefence symbolic links as if they were files?

    - by Ryan B. Lynch
    I have a directory on a Linux system that mostly contains symlinks to files on a different filesystem. I'd like to add the directory to a Subversion repository, dereferencing the symlinks in the process (treating them as the files they point to, rather than links). Generally, I'd like to be able to handle any working-copy operations with this behavior, but the 'svn add' command is where it starts, I think. The SVN client utility doesn't appear to have any options related to symlink dereferencing in the working copy. I didn't find any references to this in the manual (http://svnbook.red-bean.com/en/1.5/index.html), either. I found a poster on the SVN users mailing list who asked the same question but never received an answer, here: http://markmail.org/message/ngchfnzlmm43yj7h (That poster ended up using hard links instead of symlinks. That technique is not an option, in my case, because the real underlying files reside on a separate filesystem.) I'm using Subversion v1.6.1 on Fedora 11. For what it's worth, I know that there are alternative tools/techniques that could help approximate this behavior, but which I have to discard for various reasons. I've already considered [and dust-binned] these possibilities: - a "union" mount, merging all of the the directories containing the real files, with the SVN working-copy directory as the "top" layer in the union; - copying/moving the real files to the same filesystem as the SVN working-copy, and using hardlinks instead of symlinks; - non-SVN version control systems. These were all neat ideas, and I'm sure they are good solutions to other problems, but they won't work given the constraints of this environment and situation.

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  • NHibernate query against the key field of a dictionary (map)

    - by Carl Raymond
    I have an object model where a Calendar object has an IDictionary<MembershipUser, Perms> called UserPermissions, where MembershipUser is an object, and Perms is a simple enumeration. This is in the mapping file for Calendar as <map name="UserPermissions" table="CalendarUserPermissions" lazy="true" cascade="all"> <key column="CalendarID"/> <index-many-to-many class="MembershipUser" column="UserGUID" /> <element column="Permissions" type="CalendarPermission" not-null="true" /> </map> Now I want to execute a query to find all calendars for which a given user has some permission defined. The permission is irrelevant; I just want a list of the calendars where a given user is present as a key in the UserPermissions dictionary. I have the username property, not a MembershipUser object. How do I build that using QBC (or HQL)? Here's what I've tried: ISession session = SessionManager.CurrentSession; ICriteria calCrit = session.CreateCriteria<Calendar>(); ICriteria userCrit = calCrit.CreateCriteria("UserPermissions.indices"); userCrit.Add(Expression.Eq("Username", username)); return calCrit.List<Calendar>(); This constructed invalid SQL -- the WHERE clause contained WHERE membership1_.Username = @p0 as expected, but the FROM clause didn't include the MemberhipUsers table. Also, I really had to struggle to learn about the .indices notation. I found it by digging through the NHibernate source code, and saw that there's also .elements and some other dotted notations. Where's a reference to the allowed syntax of an association path? I feel like what's above is very close, and just missing something simple.

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  • PHP static function self:: in joomla JFactory class explanation?

    - by Carbon6
    Hi I'm looking at the code of Joomla and trying to figure out what exactly happends in this function. index.php makes a call to function $app = JFactory::getApplication('site'); jfactory.php code public static function getApplication($id = null, $config = array(), $prefix='J') { if (!self::$application) { jimport('joomla.application.application'); self::$application = JApplication::getInstance($id, $config, $prefix); } return self::$application; } application.php code.. public static function getInstance($client, $config = array(), $prefix = 'J') { static $instances; if (!isset($instances)) { $instances = array(); } ....... more code ........ return $instances[$client]; } Now I cannot figure out in function getApplication why is self:$application used. self::$application = JApplication::getInstance($id, $config, $prefix); $application is always null, what is the purpose of using this approach. I tryied modifying it to $var = JApplication::getInstance($id, $config, $prefix); and returnig it but it doesn't work. I would be very glad if someone with more knowledge could explain what is happening here detailed as possible. Many thanks.

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  • How would I go about sharing variables in a C++ class with Lua?

    - by Nicholas Flynt
    I'm fairly new to Lua, I've been working on trying to implement Lua scripting for logic in a Game Engine I'm putting together. I've had no trouble so far getting Lua up and running through the engine, and I'm able to call Lua functions from C and C functions from Lua. The way the engine works now, each Object class contains a set of variables that the engine can quickly iterate over to draw or process for physics. While game objects all need to access and manipulate these variables in order for the Game Engine itself to see any changes, they are free to create their own variables, a Lua is exceedingly flexible about this so I don't forsee any issues. Anyway, currently the Game Engine side of things are sitting in C land, and I really want them to stay there for performance reasons. So in an ideal world, when spawning a new game object, I'd need to be able to give Lua read/write access to this standard set of variables as part of the Lua object's base class, which its game logic could then proceed to run wild with. So far, I'm keeping two separate tables of objects in place-- Lua spawns a new game object which adds itself to a numerically indexed global table of objects, and then proceeds to call a C++ function, which creates a new GameObject class and registers the Lua index (an int) with the class. So far so good, C++ functions can now see the Lua object and easily perform operations or call functions in Lua land using dostring. What I need to do now is take the C++ variables, part of the GameObject class, and expose them to Lua, and this is where google is failing me. I've encountered a very nice method here which details the process using tags, but I've read that this method is deprecated in favor of metatables. What is the ideal way to accomplish this? Is it worth the hassle of learning how to pass class definitions around using libBind or some equivalent method, or is there a simple way I can just register each variable (once, at spawn time) with the global lua object? What's the "current" best way to do this, as of Lua 5.1.4?

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  • .htaccess redirect or rewrite to default language url

    - by Saif Bechan
    I have a website that is currently in Dutch. Now I want to make the website multi-language starting with English. I am not that good at .htaccess files and the information on the web is quite confusing. The website I have now uses pretty urls, so all my urls look like this: http://mydomain.com/about/info http://mydomain.com/about/contact The code that I use for that is the following: <IfModule mod_rewrite.c> RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-l RewriteRule ^(.*)$ index.php?rt=$1 [L,QSA] </IfModule> I really do not know what this means, esp the [L,QSA]. But it's ok, it works for now. But now I want to add a default redirect to the code. So it becomes as follow http://mydomain.com becomes http://mydomain.com/nl I assume all my old links http://mydomain.com/about/info will not work anymore, but that is a step I am willing to take. Can someone please help me with this code. I have seen a lot of peaces of code, but I can not find the right one.

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  • Rails can't find my route but it exists!

    - by DJTripleThreat
    Ok I have events that I want to publish/unpublish with an extra action (nonRESTful) I watched Ryan Bates' railscast on this: http://railscasts.com/episodes/35-custom-rest-actions and it got me most of the way. I think the problem is that my route is nested in an /admin section so even though when I run rake routes and get: publish_admin_event PUT /admin/events/:id/publish(.:format) {:controller=>"event_services", :action=>"publish"} This won't work in my /views/admin/index.html.erb file: <%= link_to 'Publish', publish_admin_event(event), :method => :put %> because it claims that path doesn't exist! And neither will this: <%= link_to 'Publish', {:controller => :event_services, :action => :publish}, {:method => :put, :id => event} %> and says that "No route matches {:controller=>"event_services", :action=>"publish"}" so what gives? (And I've tried restarting my server so that isn't it.) EDIT: This DOES work: <%= link_to 'Publish', "/admin/events/" + event.id.to_s + "/publish", :method => :put %> But I'd rather NOT do this.

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  • Adding defaults and indexes to a script/generate command in a Rails Template?

    - by charliepark
    I'm trying to set up a Rails Template that would allow for comprehensive set-up of a specific Rails app. Using Pratik Naik's overview (http://m.onkey.org/2008/12/4/rails-templates), I was able to set up a couple of scaffolds and models, with a line that looks something like this ... generate("scaffold", "post", "title:string", "body:string") I'm now trying to add in Delayed Jobs, which normally has a migration file that looks like this: create_table :delayed_jobs, :force => true do |table| table.integer :priority, :default => 0 # Allows some jobs to jump to the front of the queue table.integer :attempts, :default => 0 # Provides for retries, but still fail eventually. table.text :handler # YAML-encoded string of the object that will do work table.text :last_error # reason for last failure (See Note below) table.datetime :run_at # When to run. Could be Time.now for immediately, or sometime in the future. table.datetime :locked_at # Set when a client is working on this object table.datetime :failed_at # Set when all retries have failed (actually, by default, the record is deleted instead) table.string :locked_by # Who is working on this object (if locked) table.timestamps end So, what I'm trying to do with the Rails template, is to add in that :default = 0 into the master template file. I know that the rest of the template's command should look like this: generate("migration", "createDelayedJobs", "priority:integer", "attempts:integer", "handler:text", "last_error:text", "run_at:datetime", "locked_at:datetime", "failed_at:datetime", "locked_by:string") Where would I put (or, rather, what is the syntax to add) the :default values in that? And if I wanted to add an index, what's the best way to do that?

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  • Noob - Cycle through stored names and skip blanks

    - by ActiveJimBob
    NOOB trying to make my code more efficient. On scroll button push, the function 'SetName' stores a number to integer 'iName' which is index against 5 names stored in memory. If a name is not set in memeory, it skips to the next. The code works, but takes up a lot of room. Any advice appreciated. Code: #include <string.h> int iName = 0; int iNewName = 0; BYTE GetName () { return iName; } void SetName (int iNewName) { while (iName != iNewName) { switch (byNewName) { case 1: if (strlen (memory.m_nameA) == 0) new_name++; else iName = iNewName; break; case 2: if (strlen (memory.m_nameB) == 0) new_name++; else iName = iNewName; break; case 3: if (strlen (memory.m_nameC) == 0) new_name++; else iName = iNewName; break; case 4: if (strlen (memory.m_nameD) == 0) new_name++; else iName = iNewName; break; case 5: if (strlen (memory.m_nameE) == 0) new_name++; else iName = iNewName; break; default: iNewName = 1; break; } // end of case } // end of loop } // end of SetName function void main () { while(1) { if (Button_pushed) SetName(GetName+1); } // end of infinite loop } // end of main

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  • MySQL PHP SELECT throwing up an error?

    - by user1909695
    I am trying to make a comment section on my hand made site, using PHP and MySQL. I have got the comments stored in my database, but when I try to SELECT them my site throws up this error, mysql_result() [function.mysql-result]: Unable to jump to row 0 on MySQL result index 9 in /home/a9210109/public_html/comments.php on line 16 My code so far is below <?php $comment = $_POST['comment']; $mysql_host = ""; $mysql_database = ""; $mysql_user = ""; $mysql_password = ""; mysql_connect($mysql_host,$mysql_user,$mysql_password); @mysql_select_db($mysql_database) or die( "Unable to select database"); $CreateTable = "CREATE TABLE comments (comment VARCHAR(255), time VARCHAR(255));"; mysql_query($CreateTable); $UseComment = "INSERT INTO comments VALUES ('$comment')"; mysql_query($UseComment); $SelectComments = "SELECT * FROM comments"; $comments = mysql_query($SelectComments); $num=mysql_numrows($comments); $variable=mysql_result($comments,$i,"comment"); mysql_close(); ?> <a href="#" onclick="toggle_visibility('hidden');">Show/Hide Comments</a> <?php $i=0; while ($i < $num) { $comment=mysql_result($comments,$i,"comment"); echo "<div id='hidden' style='display:none'><h3>$comment</h3></div>"; $i++; } ?>

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  • Git: changes not reflecting on other checkouts - huh?

    - by Chad Johnson
    Okay, so, I have my branches (git branch -a): * chat master remotes/origin/HEAD -> origin/master remotes/origin/chat I make changes (still with the 'chat' branch checkout out), commit, and push. I go to my server, on which I have a clone of the repository, and I do a fetch: git getch then I switch to the chat branch: git checkout --track -b chat origin/chat and I event do a pull, just to make sure everything is up to date: git pull and my changes from my other computer are NOT. THERE. What the heck am I doing wrong? If I had hair, I would have pulled it out. Thankfully I am bald. When I try a 'git commit' again, I get this # On branch chat # Changed but not updated: # (use "git add/rm <file>..." to update what will be committed) # (use "git checkout -- <file>..." to discard changes in working directory) # # modified: app/controllers/chat_controller.rb # modified: app/views/dashboard/index.html.erb # modified: app/views/dashboard/layout.js.erb # modified: app/views/layouts/dashboard.html.erb # deleted: app/views/project/.tmp_edit.html.erb.55742~ # deleted: app/views/project/.tmp_edit.html.erb.83482~ # modified: public/stylesheets/dashboard/layout.css # # Untracked files: # (use "git add <file>..." to include in what will be committed) # # .loadpath # .project # config/database.yml # config/environments/development.yml # config/environments/production.yml # config/environments/test.yml # log/ no changes added to commit (use "git add" and/or "git commit -a")

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  • jCarousel - achieving an active state AND wrap:circular

    - by swisstony
    Hey folks A while back I implemented the jCarousel image solution for a client that required a numbered active state. After a bit of googling a found the answer but noticed that the preferred circular option would not work. What would happen is that once the carousel had cycled through all its (5) images, upon the return to the first, the active state would be lost, because, according to jcarousel it was actually the 6th (the index just keeps on incrementing). I just went ahead and instead used wrap:'both' which at least had a correctly functioning active state. However now the client says they dont like this effect and simply want the animation to return to position 1 after the final image. This means I need to get'wrap: 'both' working somehow. Below is my current code. Can someone please solve this one, as its a little above my head! function highlight(carousel, obejctli,liindex,listate){ jQuery('.jcarousel-control a:nth-child('+ liindex +')').attr("class","active"); }; function removehighlight(carousel, obejctli,liindex,listate){ jQuery('.jcarousel-control a:nth-child('+ liindex +')').removeAttr("class","active"); }; jQuery('#mycarousel').jcarousel({ initCallback: mycarousel_initCallback, auto: 5, wrap: 'both', vertical: true, scroll: 1, buttonNextHTML: null, buttonPrevHTML: null, animation: 1000, itemVisibleInCallback: highlight, itemVisibleOutCallback: removehighlight }); }); Thanks in advance

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  • How to get components from a JFrame with a GridLayout?

    - by NlightNfotis
    I have a question about Java and JFrame in particular. Let's say I have a JFrame that I am using with a GridLayout. Supposing that I have added JButtons in the JFrame, how can I gain access to the one I want using it's position (by position, I mean a x and a y, used to define the exact place on the Grid). I have tried several methods, for instance getComponentAt(int x, int y), and have seen that those methods do not work as intended when combined with GridLayout, or at least don't work as intended in my case. So I tried using getComponent(), which seems fine. The latest method, that seems to be on a right track for me is (assuming I have a JFrame with a GridLayout with 7 rows and 7 columns, x as columns, y as rows): public JButton getButtonByXAndY(int x, int y) { return (JButton) this.getContentPane().getComponent((y-1) * 7 + x); } Using the above, say I want to get the JButton at (4, 4), meaning the 25th JButton in the JFrame, I would index through the first 21 buttons at first, and then add 4 more, finally accessing the JButton I want. Problem is this works like that in theory only. Any ideas? P.S sorry for linking to an external website, but stack overflow won't allow me to upload the image, because I do not have the required reputation.

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  • Asp.Net MVC - Binding of parameter to model value!

    - by Pino
    This seems like the model binding is causing me issues. Essentially I have a model called ProductOption and for the purpose of this question it has 2 fields ID (Int) PK ProductID (Int) FK I have a standard route set-up context.MapRoute( "Product_default", "Product/{controller}/{action}/{id}", new { controller = "Product", action = "Index", id = UrlParameter.Optional } ); and if the user wants to add an option the URL is, /Product/Options/Add/1 in the above URL 1 is the ProductID, I have the following code to return a blank model the the view, [HttpGet] public ActionResult Add(int id) { return View("Manage", new ProductOptionModel() { ProductID = id }); } Now in my view I keep a hidden field <%= Html.HiddenFor(x=>x.ID) %> This is used to determine (on submit) if we are editing or adding a new option. However the Model binder in .net seems to replace .ID (Which was 0 when leaving the above get actionresult) with 1 (or the value of the id parameter in the URL) How can I stop or work around this? ViewModel public class ProductExtraModel { //Database public int ID { get; set; } public string Name { get; set; } public int ProductID { get; set; } public ProductModel Product { get; set; } }

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  • Pointing to array element

    - by regular
    What I'm trying to achieve is say i have an array, i want to be able to modify a specific array element throughout my code, by pointing at it. for example in C++ i can do this int main(){ int arr [5]= {1,2,3,4,5}; int *c = &arr[3]; cout << arr[3] <<endl; *c = 0; cout << arr[3]<<endl; } I did some googling and there seems to be a way to do it through 'unsafe', but i don't really want to go that route. I guess i could create a variable to store the indexes, but I'm actually dealing with slightly more complexity (a list within a list. so having two index variables seems to add complexity to the code.) C# has a databinding class, so what I'm currently doing is binding the array element to a textbox (that i have hidden) and modifying that textbox whenever i want to modify the specific array element, but that's also not a good solution (since i have a textbox that's not being used for its intended purpose - a bit misleading).

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  • Create new or update existing entity at one go with JPA

    - by Alex R
    A have a JPA entity that has timestamp field and is distinguished by a complex identifier field. What I need is to update timestamp in an entity that has already been stored, otherwise create and store new entity with the current timestamp. As it turns out the task is not as simple as it seems from the first sight. The problem is that in concurrent environment I get nasty "Unique index or primary key violation" exception. Here's my code: // Load existing entity, if any. Entity e = entityManager.find(Entity.class, id); if (e == null) { // Could not find entity with the specified id in the database, so create new one. e = entityManager.merge(new Entity(id)); } // Set current time... e.setTimestamp(new Date()); // ...and finally save entity. entityManager.flush(); Please note that in this example entity identifier is not generated on insert, it is known in advance. When two or more of threads run this block of code in parallel, they may simultaneously get null from entityManager.find(Entity.class, id) method call, so they will attempt to save two or more entities at the same time, with the same identifier resulting in error. I think that there are few solutions to the problem. Sure I could synchronize this code block with a global lock to prevent concurrent access to the database, but would it be the most efficient way? Some databases support very handy MERGE statement that updates existing or creates new row if none exists. But I doubt that OpenJPA (JPA implementation of my choice) supports it. Event if JPA does not support SQL MERGE, I can always fall back to plain old JDBC and do whatever I want with the database. But I don't want to leave comfortable API and mess with hairy JDBC+SQL combination. There is a magic trick to fix it using standard JPA API only, but I don't know it yet. Please help.

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  • CSS style refresh in IE after dynamic removal of style link

    - by rybz
    Hi! I've got a problem with the dynamic style manipulation in IE7 (IE8 is fine). Using javascript I need to add and remove the < link / node with the definition of css file. Adding and removing the node as a child of < head / works fine under Firefox. Unfortunately, after removing it in the IE, although The tag is removed properly, the page style does not refresh. In the example below a simple css (makes background green) is appended and removed. After the removal in FF the background turns default, but in IE stays green. index.html <html> <head> </head> <script language="javascript" type="text/javascript"> var node; function append(){ var headID = document.getElementsByTagName("head")[0]; node = document.createElement('link'); node.type = 'text/css'; node.rel = 'stylesheet'; node.href = "s.css"; node.media = 'screen'; headID.appendChild(node); } function remove(){ var headID = document.getElementsByTagName("head")[0]; headID.removeChild(node); } </script> <body> <div onClick="append();"> add </div> <div onClick="remove();"> remove </div> </body> </html> And the style sheet: s.css body { background-color:#00CC33 } Here is the live example: http://rlab.pl/dynamic-style/ Is there a way to get it working?

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  • Why does SQLite take such a long time to fetch the data?

    - by Derk
    I have two possible queries, both giving the result set I want. Query one takes about 30ms, but 150ms to fetch the data from the database. SELECT id FROM featurevalues as featval3 WHERE featval3.feature IN (?,?,?,?) AND EXISTS ( SELECT 1 FROM product_to_value, product_to_value as prod2, features, featurevalues WHERE product_to_value.feature = features.int AND product_to_value.value = featurevalues.id AND features.id = ? AND featurevalues.id IN (?,?) AND product_to_value.product = prod2.product AND prod2.value = featval3.id ) Query two takes about 3ms -this is the one I therefore prefer-, but also takes 170ms to fetch the data. SELECT ( SELECT prod2.value FROM product_to_value, product_to_value as prod2, features, featurevalues WHERE product_to_value.feature = features.int AND product_to_value.value = featurevalues.id AND features.id = ? AND featurevalues.id IN (?,?) AND product_to_value.product = prod2.product AND prod2.value = featval3.id ) as id FROM featurevalues as featval3 WHERE featval3.feature IN (?,?,?,?) The 170ms seems to be related to the number of rows from table featval3. After an index is used on featval3.feature IN (?,?,?,?), 151 items "remain" in featval3. Is there something obvious I am missing regarding the slow fetching? As far as I know everything is properly indexed.. I am confused because the second query only takes a blazing 3ms to run.

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  • Efficient algorithm for Next button on a MySQL result set

    - by David Grayson
    I have a website that lets people view rows in a table (each row is a picture). There are more than 100,000 rows. You can view different subsets of the rows, and you can view them with different sort orders. While you are viewing one of the rows, you can click the "Next" or "Previous" buttons to go the next/previous row in the list. How would you implement the "Next" and "Previous" features of the website? More specifically, if you have an arbitrary query that returns a list of up to 100,000+ rows, and you know some information about the current row someone is viewing, how do you determine the NEXT row efficiently? Here is the pseudo-code of the solution I came up with when the website was young, and it worked well when there were only 1000 rows, but now that there are 100,000 rows I think it is eating up too much memory. int nextRowId(string query, int currentRowId) { array allRowIds = mysql_query(query); // Takes up a lot of memory! int currentIndex = (index of currentRowId in allRowIds); // Takes time! return allRowIds[currentIndex+1]; } While you are thinking about this problem, remember that the website can store more information about the current row than just its ID (for example, the position of the current row in the result set), and this information can be used as a hint to help determine the ID of the next row. Edit: Sorry for not mentioning this earlier, but this isn't just a static website: rows can often be added to the list, and rows can be re-ordered in the list. (Much rarer, rows can be removed from the list.) I think that I should worry about that kind of thing, but maybe you can convince me otherwise.

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  • Telerik RadGrid: grid clientside pagination

    - by ram
    I have a web service which returns me some data,I am massaging this data and using this as datasource for my radgrid (telerik). The datasource is quite large, and would like to paginate it. I found couple of problems when I paginate it in the server side I have to bind the grid again for pagination, which essentially means I have to make a call to WS again to get the data. This is an expensive call for me. I would rather forgo the benefits of pagination and would display all the results in the same page, except for it would be a bit clumsy During the postback RadGrid1.Items.Count happens to be the number of items getting paginated (25- in my case) which is expected as all the items in the datasource are not getting bound. This of course is not an issue. The real issue is that we have some checkboxes which get checked based on some business condition. We add this to our business object/DB later. So if the user has not navigated all the pages, these "checked" items do not get added as pagination limits the "Items" in the grid to those which get bound for that particular page index. My Thoughts: I would rather have some sort of client side pagination, where we can hide/show contents than going to the server and doing a databind every time. Though it will return all the results, the UI will not be clumsy and the grid would have "all the items" during postback Is there a way to do it ? If it were a regular asp.net gridView, can someone point me to a good article which would serve my purpose Ram PS: who else think radgrid is crazy ? (unfortunately I did not make this choice)

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  • Exception calling UpdateModel - Value cannot be null or empty

    - by James Alexander
    This is probably something silly I'm missing but I'm definitely lost. I'm using .NET 4 RC and VS 2010. This is also my first attempt to use UpdateModel in .NET 4, but every time I call it, I get an exception saying Value cannont be null or empty. I've got a simple ViewModel called LogOnModel: [MetadataType(typeof(LogOnModelMD))] public class LogOnModel { public string Username { get; set; } public string Password { get; set; } public class LogOnModelMD { [StringLength(3), Required] public object Username { get; set; } [StringLength(3), Required] public object Password { get; set; } } } My view uses the new strongly typed helpers in MVC2 to generate a textbox for username and one for the password. When I look at FormCollection in my controller method, I see values for both coming through. And last but not least, here's are post controller methods: // POST: /LogOn/ [HttpPost] public ActionResult Index(FormCollection form) { var lm = new LogOnModel(); UpdateModel(lm, form); var aservice = new AuthenticationService(); if (!aservice.AuthenticateLocal(lm.Username, lm.Password)) { ModelState.AddModelError("User", "The username or password submitted is invalid, please try again."); return View(lm); } return Redirect("~/Home"); } Can someone please lend some insight into why UpdateModel would be throwing this exception? Thanks!

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