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  • Can I safely bind to data on multi-threaded applications?

    - by Paul
    Hi everyone, I'm trying to solve a classic problem - I have a multi-threaded application which runs some processor-intensive calculations, with a GUI interface. Every time one of the threads has completed a task, I'd like to update a status on a table taskID | status I use DataGridView and BindingList in the following way: BindingList<Task> tasks; dataGridView.DataSource = tasks public class Task : INotifyPropertyChanged { ID{get;} Status{get;set;} } Can a background thread safely update a task's status? and changes will be seen in the correct order in the GUI? Second Question: When do I need to call to PropertyChanged? I tried running with and without the call, didn't seem to bother.. Third Question: I've seen on MSDN that dataGridView uses BindingSource as a mediator between DataGridView.DataSource and BindingList Is this really necessary?

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  • Database design advice needed.

    - by user346271
    Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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  • How do I transfer configuration data into injected objects?

    - by louis
    I used to use Spring.Net and want to switch to Ninject 1.5 (I have to use .NET2, since some unlucky guy like me still needs to consider users working with win 2k). I used to have everything done in xml and only invoke the container during startup. In this way, only very limited codes are depending on container. I have scenarios like this and I wonder how to do the same in Ninject. I have external config file, which are the items the end users can change basing on their environment/preferences. And some of my objects depends on those values to initialize. Mostly they are primary values, but some times can be list/dictionaries/etc.

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  • calling hibernate callback

    - by vrkmurali
    HibernateCallback callback=new HibernateCallback() { @Override public Object doInHibernate(Session session) throws HibernateException, SQLException { Transaction transaction=session.beginTransaction(); Query query2 = session.createSQLQuery( "select user_id,user_name from usermasterdao where user_id not in('select usermaster_id from LoginHistoryDAO where logindate between :fromdate and :todate')"); ((SQLQuery) query2).addEntity(UserMasterDAO.class); //query.setParameter("stockCode", "7277"); query2.setParameter("todate", toDate); query2.setParameter("fromdate", fromDate); List result2 = query2.list(); listofNotUsing=result2; System.out.println(result2.size()+"sizeeee"); transaction.commit(); return result2;}} while executing the command getting error like as follows com.vaadin.event.ListenerMethod$MethodException: Invocation of method notUsingButton in com.iton.ioffice.admin.LoginHistory failed. at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:530) at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164) at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219) at com.vaadin.ui.Button.fireClick(Button.java:567) at com.vaadin.ui.Button.changeVariables(Button.java:223) at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVariables(AbstractCommunicationManager.java:1460) at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1404) at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1329) at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:761) at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:318) at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Thread.java:619) Caused by: org.springframework.orm.hibernate3.HibernateQueryException: could not locate named parameter [todate]; nested exception is org.hibernate.QueryPa rameterException: could not locate named parameter [todate] at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:656) at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412) at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:411) at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:339) at com.iton.ioffice.admin.DAO.impl.UserServiceDAOImpl.outOfProcess(UserServiceDAOImpl.java:304) at com.iton.ioffice.admin.LoginHistory.notUsingButton(LoginHistory.java:298) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:520) ... 23 more Caused by: org.hibernate.QueryParameterException: could not locate named parameter [todate] at org.hibernate.engine.query.ParameterMetadata.getNamedParameterDescriptor(ParameterMetadata.java:99) at org.hibernate.engine.query.ParameterMetadata.getNamedParameterExpectedType(ParameterMetadata.java:105) at org.hibernate.impl.AbstractQueryImpl.determineType(AbstractQueryImpl.java:437) at org.hibernate.impl.AbstractQueryImpl.setParameter(AbstractQueryImpl.java:407) at com.iton.ioffice.admin.DAO.impl.UserServiceDAOImpl$4.doInHibernate(UserServiceDAOImpl.java:285) at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:406) ... 31 more please help me

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  • How can i attach data to a JTA transaction? (or uniquely identify it)

    - by kwyjibo
    I have a getStockQuote() function that will get a current stock quote for a symbol from the stock market. My goal is that within a JTA transaction, the first call to getStockQuote() will fetch a stock quote, but all subsequent calls within the same transaction will reuse the same stock quote (e.g.: it will not try to fetch a new quote). If a different transaction starts, or another transaction runs concurrently, i would expect the other transaction to fetch its own stock quote on its first call. This would be similar to how you can configure JPA providers to only fetch a database row from the database once, and use the cached value for subsequent access to the same database row within the transaction. Does anyone have tips on how this can be achieved?

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  • How to properly assign a value to the member of a struct that has a class data type?

    - by sasayins
    Hi, Please kindly see below for the codes. Its compiling successfully but the expected result is not working. Im very confused because my initialization of the array is valid, //cbar.h class CBar { public: class CFoo { public: CFoo( int v ) : m_val = v {} int GetVal() { return m_val; } private: int m_val; }; public: static const CFoo foo1; static const CFoo foo2; public: CBar( CFoo foo ) m_barval( foo.GetVal() ){} int GetFooVal() { return m_barval; } private: int m_barval; }; //cbar.cpp const CBar::CFoo foo1 = CBar::CFoo(2); const CBar::CFoo foo2 = CBar::CFoo(3); //main.cpp struct St { CBar::CFoo foo; }; St st[] = { CBar::foo1, CBar::foo2 }; for( int i=0; i<sizeof(st)/sizeof(St); i++ ) { CBar cbar( st[i].foo ); std::cout << cbar.GetFooVal() << std::endl; } But then when I change the St::foo to a pointer. And like assign the address of CBar::foo1 or CBar::foo2, its working, like this, //main.cpp struct St { const CBar::CFoo *foo; }; St st[] = { &CBar::foo1, &CBar::foo2 }; for( int i=0; i<sizeof(st)/sizeof(St); i++ ) { CBar cbar( *st[i].foo ); std::cout << cbar.GetFooVal() << std::endl; } The real problem is. The app should output 2 3 Please advice. Many thanks.

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  • Best tree/heap data structure for fixed set of nodes with changing values + need top 20 values?

    - by user350139
    I'm writing something like a game in C++ where I have a database table containing the current score for each user. I want to read that table into memory at the start of the game, quickly change each user's score while the game is being played in response to what each user does, and then when the game ends write the current scores back to the database. I also want to be able to find the 20 or so users with the highest scores. No users will be added or deleted during the short period when the game is being played. I haven't tried it yet, but updating the database might take too much time during the period when the game is being played. Fixed set of users (might be 10,000 to 50,000 users) Will map user IDs to their score and other user-specific information. User IDs will be auto_increment values. If the structure has a high memory overhead that's probably not an issue. If the program crashes during gameplay it can just be re-started. Quickly get a user's current score. Quickly add to a user's current score (and return their current score) Quickly get 20 users with highest score. No deletes. No inserts except when the structure is first created, and how long that takes isn't critical. Getting the top 20 users will only happen every five or ten seconds, but getting/adding will happen much more frequently. If not for the last, I could just create a memory block equal to sizeof(user) * max(user id) and put each user at user id * sizeof(user) for fast access. Should I do that plus some other structure for the Top 20 feature, or is there one structure that will handle all of this together?

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  • getting a combo box that has a row source equal to a query - and the query takes data from a form -

    - by primus285
    I have a combo box with a row source based on an SQL query about like SELECT DISTINCT Database_New.ASEC FROM Database_New WHERE Database_New.Date= DateSerial([cboYear], 1, 1) And Database_New.Date<= DateSerial([cboYear], 12, 31); the trouble is that if I change the value of cboYear, the values in the drop down cboASEC do not update. I have to open the query, save it and close it to get the thing to update while I have the form open. Is there a way to get the cboASEC to update somehow? maybe a little tidbit of code in the cboYear - afterupdate?

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  • Why would you precede the main() function in C with a data type?

    - by Milktrader
    Many are familiar with the hello world program in C #include <stdio.h> main () { printf ("hello world"); return 0; } Why do some precede the main () function with int as in: int main() Also, I've seen the word 'void' entered inside the () as in: int main(void) It seems like extra typing for nothing, but maybe it's a best practice that pays dividends in other situations? Also, why precede main() with an int if you're returning a character string? If anything, one would expect: char main(void) I'm also foggy about why we return 0 at the end of the function.

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  • Store data in an inconvenient table or create a derived table?

    - by user1705685
    I have a certain predefined database structure that I am stuck with. The question is whether this structure is OK for ORM or I whether should add a processing layer that would create a more convenient structure every time something is inserted into the original DB. To simplify, here's what it kind of looks like. I have a person table: PersonId Name And I have a properties table: PersonId PropertyType PropertyValue So, for person John Doe... (1, 'John Doe') ...I could have three properties: (1, 'phone', '555-55-55'), (1, 'email', '[email protected]), (1, 'type', 'employee') By using ORM I would like to get a "person" object that would have properties "name", "phone", "email", "type". Can Propel do that? How efficient is it? Is it a better idea to create a table with columns "phone", "email", "type" and fill it automatically as new rows are inserted into the properties table?

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  • Best practice: How to persist simple data without a database in django?

    - by Infinity
    I'm building a website that doesn't require a database because a REST API "is the database". (Except you don't want to be putting site-specific things in there, since the API is used by mostly mobile clients) However there's a few things that normally would be put in a database, for example the "jobs" page. You have master list view, and the detail views for each job, and it should be easy to add new job entries. (not necessarily via a CMS, but that would be awesome) e.g. example.com/careers/ and example.com/careers/77/ I could just hardcode this stuff in templates, but that's no DRY- you have to update the master template and the detail template every time. What do you guys think? Maybe a YAML file? Or any better ideas? Thx

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  • oracle index for string column - does format of data affects quality of index?

    - by Jayan
    We have following type of "Unique ID" column for many tables in the database (Oracle). It is a string with following format <randomnumber>-<ascendingnumber>-<machinename> So we have some thing like this U1234-12345-NBBJD U1234-12346-NBBJD U1234-12347-NBBJD U1234-12348-NBBJD U1234-12349-NBBJD The UID value is unique, we have unique index on them. Does the following format is more efficient than above for index scans? NBBJD-U1234-12345 NBBJD-U1234-12346 NBBJD-U1234-12347 NBBJD-U1234-12348 NBBJD-U1234-12349

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  • Is it possible to capture data from a WHERE clause?

    - by Kristopher Ives
    I have a scenario where I'm calculating something in the WHERE clause of my SQL, but I also want to get that calculation - since it's expensive. Is it possible to get the results of something done in the WHERE clause, like this: SELECT `foo` FROM `table` WHERE (foo = LongCalculation()) Wishful thinking, or possible with MySQL?

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  • How can I make the Entity data model designer use my database column descriptions?

    - by Jack
    I am using EF4 with Visual Studio 2010. I have a SQL database already created and all my columns are documented with the Description property in SQL management studio. When I create the edmx in Visual Studio, how can I make it read those descriptions and use them to add comments to my generated classes? I know I can use the Summary and LongDescription in the edmx properties but I'm looking for a way to do this without having to copy and paste every description. Thanks!

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  • jquery autosuggest not firing (webform)

    - by Abu Hamzah
    is that something wrong in the below code? its not firing at all $(document).ready(function() { $("#<%=txtHost.ClientID%>").autocomplete("HostService.asmx/GetHosts",{ dataType: 'json' ,contentType: "application/json; charset=utf-8" ,parse: function(data){ var rows = Array(); debugger for(var i = 0; i<data.length; i++){ rows[i] = {data:data[i], value:data[i].LName, result:data[i].LName}; } return rows; } ,formatItem: function(row, i, max){ return data.LName + ", " + data.FName; } }); }); <script src="Scripts/jquery.autocomplete.js" type="text/javascript"></script> <asp:TextBox ID="txtHost" runat='server'></asp:TextBox>

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  • Looping class, for template engine kind of thing

    - by tarnfeld
    Hey, I am updating my class Nesty so it's infinite but I'm having a little trouble.... Here is the class: <?php Class Nesty { // Class Variables private $text; private $data = array(); private $loops = 0; private $maxLoops = 0; public function __construct($text,$data = array(),$maxLoops = 5) { // Set the class vars $this->text = $text; $this->data = $data; $this->maxLoops = $maxLoops; } // Loop funtion private function loopThrough($data) { if( ($this->loops +1) > $this->maxLoops ) { die("ERROR: Too many loops!"); } else { $keys = array_keys($data); for($x = 0; $x < count($keys); $x++) { if(is_array($data[$keys[$x]])) { $this->loopThrough($data[$keys[$x]]); } else { return $data[$keys[$x]]; } } } } // Templater method public function template() { echo $this->loopThrough($this->data); } } ?> Here is the code you would use to create an instance of the class: <?php // The nested array $data = array( "person" => array( "name" => "Tom Arnfeld", "age" => 15 ), "product" => array ( "name" => "Cakes", "price" => array ( "single" => 59, "double" => 99 ) ), "other" => "string" ); // Retreive the template text $file = "TestData.tpl"; $fp = fopen($file,"r"); $text = fread($fp,filesize($file)); // Create the Nesty object require_once('Nesty.php'); $nesty = new Nesty($text,$data); // Save the newly templated text to a variable $message $message = $nesty->template(); // Print out $message on the page echo("<pre>".$message."</pre>"); ?> Any ideas?

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  • Need help debugging a huge chunk of JSON data...

    - by meder
    I have a huge chunk, so large that I can't manually edit the file and need to read it in and do regex operations to see what's wrong. Basically - my server is PHP 5.1.6 and I can't update it. This features an older json_decode which is less featured than the 5.2/5.3 versions. json_decode returns NULL and json_last_error is being invoked but the function doesn't exist except in PHP 5.3 so I'm manually trying to see what's wrong. $regex = '#[^0-9"$a-zA-Z{:}().]#'; $json = preg_replace( $regex, '', $json ); $tree = json_decode ( $json, true ); var_dump($tree); // NULL A snippet of the JSON.. somewhere in the middle {"109":0,"103":1,"102":59,"101":70,"100":4299,"94":0,"50":51,"46":0,"45":0,"44":0,"43":0,"42":0,"23":0,"22":0,"18":0,"17":1,"16":1,"13":160,"8":4298}},"2":{"d":{"109":0,"103":92,"102":54,"101":53,"100":4301,"94":0,"50":4278,"49":328,"46":1,"45":0,"44":1,"43":0,"42":0,"26":0,"23":0,"22":0,"18":0,"17":1,"16":1,"8":4300},"m":{"94":1,"100":1,"26":1,"50":1,"8":1,"49":1,"18":1,"43":1,"42":1,"109":1},"c":{"\/":{"d":{"109":0,"100":4301,"94":0,"50":4278,"49":328,"43":0,"42":0,"26":0,"18":0,"8":4300}},"G":{"d":{"109":1,"100":4303,"94":1,"68":17,"50":64,"49":53,"43":1,"42":1,"34":0,"18":1,"13":2216,"11":0,"8":4302}}}},"3": The }}}} is suspicious but this probably just closes 4 nested object literals. Would appreciate any insight.

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  • Question about ASP.NET MVC and static data (ie. images, scripts, etc)

    - by Pure.Krome
    Hi folks, If i have a request for a resource in my ASP.NET MVC1 (or 2) web app for a static resource, say ... an image or a javascript file or a css file ... does the .NET framework try and see if the request matches the route list ... and eventually can't find a controller for it? eg. Resource: /Content/Images/Foo.png Does this request go through my route list .. fails to match any controllers / actions to this request and then .. i donno ... attempt that path directly?

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  • How can i add to dataGridView1 a data to the last row/column?

    - by user3681442
    In top of form1 i did: private System.Timers.Timer _refreshTimer; private int _thisProcess; Then in the Form1 Load event: _thisProcess = Process.GetCurrentProcess().Id; InitializeRefreshTimer(); PopulateApplications(); Then the timer init method: void InitializeRefreshTimer() { _refreshTimer = new System.Timers.Timer(5000); _refreshTimer.SynchronizingObject = this; _refreshTimer.Elapsed += new System.Timers.ElapsedEventHandler(TimerToUpdate_Elapsed); _refreshTimer.Start(); } Then the timer elapsed event: void TimerToUpdate_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { PopulateApplications(); } In the end the Populate method: void PopulateApplications() { dataGridView1.Rows.Clear(); foreach (Process p in Process.GetProcesses(".")) { if (p.Id != _thisProcess) { try { if (p.MainWindowTitle.Length > 0) { String status = p.Responding ? "Running" : "Not Responding"; dataGridView1.Rows.Add( p.MainWindowTitle, status); } } catch { } } } } The variable status show in the column2 but let's say i want that status will be display for each process/app in column5 ? How can i move it ? EDIT** Tried this: void PopulateApplications() { dataGridView1.Rows.Clear(); foreach (Process p in Process.GetProcesses(".")) { if (p.Id != _thisProcess) { try { if (p.MainWindowTitle.Length > 0) { var icon = Icon.ExtractAssociatedIcon(p.MainModule.FileName); Image ima = icon.ToBitmap(); img.Image = ima; img.HeaderText = "Image"; img.Name = "img"; String status = p.Responding ? "Running" : "Not Responding"; dataGridView1.Rows.Add(img, p.MainWindowTitle, status); } } catch { } } } } I moved the variable img to the top of the form. The problem is i see in each row this: DataGridViewImageColumn { Name=img, Index=-1 } And i don't see the icon it self. Why ?

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  • jQuery Mobile: How to run a callback-function before $.mobile.changePage?

    - by Jugi84
    I'm setting up a mobile app with jQuery Mobile and PhoneGap. What I want to do is that when I click link with id "news_link" I want jQuery to fetch data from database and put it to jQm's collapsible set. In my solution, I've wanted to use $.mobile.changePage inside callback functions because I want to wait until the data has been fetched and put inside the container before the code changes page. Here's the code: $(function() { $('#news_link').click(function(){ loadNewsFromDB(function(){ $.mobile.changePage( $("#news"), { transition: "slideup"} ); }); }); loadNewsFromDB is PhoneGap's SQLite database function which would fetch the data with more callback functions from database. The contents would be put to desired container with .html-function function loadNewsFromDB(){ //some code here theDB.transaction(function(tx) { tx.executeSql(sqlStr, [], onLoadNewsSuccess, onLoadNewsError); },onTxError, onTxSuccess); function onLoadNewsSuccess(tx, results){ //some code here $("#newsSet").html(htmlCodeAndContentToPut); Html is jQm's basic ui-modules: <!-- some html code here --!> <div data-role="page" id="news"> <div data-role="content"> <div id="newsSet" data-role="collapsible-set" data-mini="true"> With debugging I know that the code work up until it works very well unti it arrives to $.mobile.changePage-function. Somehow it doesn't change the page. I've checked the function it works well in other occasions, but not inside callback-functions. I would be very grateful if someone would give me a hand am I not seeing something obviously wrong or is something more specific? What other workarounds there is for fetching the data from SQLite, waiting for data to be fetched, putting the data to container and then changing the pages?

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