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• Why put a DAO layer over a persistence layer (like JDO or Hibernate)

  - by Todd Owen

  Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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• swf listens to XML, AS3

  - by VideoDnd

  My swf listens to XML from a socket and document. How do I get 'my variables' to grab XML from the socket instead of the XML document? PURPOSE My purpose is to control variables with a XML Socket Server. I hope my question is clear, but ask if there's any questions. EXAMPLE Flash File import flash.net.*; import flash.display.*; import flash.events.*; import flash.system.Security; import flash.utils.Timer; import flash.events.TimerEvent; //MY VARIABLES, LINE 8-12 var timer:Timer = new Timer(10); var myString:String = ""; var count:int = 0; var myStg:String = ""; var fcount:int = 0; var xml_s=new XMLSocket(); xml_s.addEventListener(Event.CONNECT, socket_event_catcher);//OnConnect// xml_s.addEventListener(Event.CLOSE, socket_event_catcher);//OnDisconnect// xml_s.addEventListener(IOErrorEvent.IO_ERROR, socket_event_catcher);//Unable To Connect// xml_s.addEventListener(DataEvent.DATA, socket_event_catcher);//OnDisconnect// xml_s.connect("localhost", 1999); function socket_event_catcher(Event):void { switch (Event.type) { case 'ioError' : trace("ioError: " + Event.text);//Unable to Connect :(// break; case 'connect' : trace("Connection Established!");//Connected :)// break; case 'data' : trace("Received Data: " + Event.data); //var myXML:XML=new XML(Event.data); //trace("myXML.body.file: " + myXML.body.file); //var myLoader:String=myXML.body.file; //var urlReq:URLRequest=new URLRequest(myLoader); //trace("file to load URL: " + urlReq); break; case 'close' : trace("Connection Closed!");//OnDisconnect :( // xml_s.close(); break; } } //LOAD XML var myXML:XML; var myLoader:URLLoader = new URLLoader(); myLoader.load(new URLRequest("time.xml")); myLoader.addEventListener(Event.COMPLETE, processXML); //var myXML:XML=new XML(Event.data); //trace("myXML.body.file: " + myXML.body.file); //var DOINK:String=myXML.body.file; //var urlReq:URLRequest=new URLRequest(DOINK); //trace("file to load URL: " + urlReq); //PARSE XML function processXML(e:Event):void { myXML = new XML(e.target.data); trace(myXML.COUNT.text()); //-77777 //grab the data as a string myString = myXML.COUNT.text() //grab the data as an int count = int(myXML.COUNT.text()); //grab the data as a string myString = myXML.COUNT.text() //grab the data as an int count = int(myXML.COUNT.text()); //grab the data as a string myStg = myXML.COUNT.text() //grab the data as an int fcount = int(myXML.COUNT.text()); //grab the data as a string myStg = myXML.COUNT.text() //grab the data as an int fcount = int(myXML.COUNT.text()); trace("String: ", myString); trace("Int: ", count); trace(count - 1); //just to show you that it's a number that you can do math with (-77778) //TEXT var text:TextField = new TextField(); text.text = myString; addChild(text); } Ruby Server 'Snippet' msg1 = {"msg" => {"head" => {"type" => "frctl", "seq_no" => seq_no, "version" => 1.0}, "SESSION" => {"text" => "88888", "timer" => -1000, "count" => 10, "fcount" => "10"}}} XML <?xml version="1.0" encoding="utf-8"?> <SESSION> <TIMER TITLE="speed">100</TIMER> <COUNT TITLE="starting position">88888</COUNT> <FCOUNT TITLE="ramp">1000</FCOUNT> </SESSION> ENVIROMENT AS3 Ruby 186-25 PROBLEM Coding errors "coercion of value"

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• Mysql InnoDB performance optimization and indexing

  - by Davide C

  Hello everybody, I have 2 databases and I need to link information between two big tables (more than 3M entries each, continuously growing). The 1st database has a table 'pages' that stores various information about web pages, and includes the URL of each one. The column 'URL' is a varchar(512) and has no index. The 2nd database has a table 'urlHops' defined as: CREATE TABLE urlHops ( dest varchar(512) NOT NULL, src varchar(512) DEFAULT NULL, timestamp timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, KEY dest_key (dest), KEY src_key (src) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 Now, I need basically to issue (efficiently) queries like this: select p.id,p.URL from db1.pages p, db2.urlHops u where u.src=p.URL and u.dest=? At first, I thought to add an index on pages(URL). But it's a very long column, and I already issue a lot of INSERTs and UPDATEs on the same table (way more than the number of SELECTs I would do using this index). Other possible solutions I thought are: -adding a column to pages, storing the md5 hash of the URL and indexing it; this way I could do queries using the md5 of the URL, with the advantage of an index on a smaller column. -adding another table that contains only page id and page URL, indexing both columns. But this is maybe a waste of space, having only the advantage of not slowing down the inserts and updates I execute on 'pages'. I don't want to slow down the inserts and updates, but at the same time I would be able to do the queries on the URL efficiently. Any advice? My primary concern is performance; if needed, wasting some disk space is not a problem. Thank you, regards Davide

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• Prevent lazy loading in nHibernate

  - by Ciaran

  Hi, I'm storing some blobs in my database, so I have a Document table and a DocumentContent table. Document contains a filename, description etc and has a DocumentContent property. I have a Silverlight client, so I don't want to load up and send the DocumentContent to the client unless I explicity ask for it, but I'm having trouble doing this. I've read the blog post by Davy Brion. I have tried placing lazy=false in my config and removing the virtual access modifier but have had no luck with it as yet. Every time I do a Session.Get(id), the DocumentContent is retrieved via an outer join. I only want this property to be populated when I explicity join onto this table and ask for it. Any help is appreciated. My NHibernate mapping is as follows: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Jrm.Model" namespace="Jrm.Model"> <class name="JrmDocument" lazy="false"> <id name="JrmDocumentID"> <generator class="native" /> </id> <property name="FileName"/> <property name="Description"/> <many-to-one name="DocumentContent" class="JrmDocumentContent" unique="true" column="JrmDocumentContentID" lazy="false"/> </class> <class name="JrmDocumentContent" lazy="false"> <id name="JrmDocumentContentID"> <generator class="native" /> </id> <property name="Content" type="BinaryBlob" lazy="false"> <column name="FileBytes" sql-type="varbinary(max)"/> </property> </class> </hibernate-mapping> and my classes are: [DataContract] public class JrmDocument : ModelBase { private int jrmDocumentID; private JrmDocumentContent documentContent; private long maxFileSize; private string fileName; private string description; public JrmDocument() { } public JrmDocument(string fileName, long maxFileSize) { DocumentContent = new JrmDocumentContent(File.ReadAllBytes(fileName)); FileName = new FileInfo(fileName).Name; } [DataMember] public virtual int JrmDocumentID { get { return jrmDocumentID; } set { jrmDocumentID = value; OnPropertyChanged("JrmDocumentID"); } } [DataMember] public JrmDocumentContent DocumentContent { get { return documentContent; } set { documentContent = value; OnPropertyChanged("DocumentContent"); } } [DataMember] public virtual long MaxFileSize { get { return maxFileSize; } set { maxFileSize = value; OnPropertyChanged("MaxFileSize"); } } [DataMember] public virtual string FileName { get { return fileName; } set { fileName = value; OnPropertyChanged("FileName"); } } [DataMember] public virtual string Description { get { return description; } set { description = value; OnPropertyChanged("Description"); } } } [DataContract] public class JrmDocumentContent : ModelBase { private int jrmDocumentContentID; private byte[] content; public JrmDocumentContent() { } public JrmDocumentContent(byte[] bytes) { Content = bytes; } [DataMember] public int JrmDocumentContentID { get { return jrmDocumentContentID; } set { jrmDocumentContentID = value; OnPropertyChanged("JrmDocumentContentID"); } } [DataMember] public byte[] Content { get { return content; } set { content = value; OnPropertyChanged("Content"); } } }

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• Beyond core java

  - by Paul

  Coming to the end of the first year of my CS degree, we've done some Java but just the core stuff; manipulating strings and arrays, inheritance, implementing logic etc. I visit this website daily and I see so much stuff that is beyond me; using frameworks; managing databases etc. It makes me feel like I've just learned the syntax of Java, and there is so much more to do with it. My question is though, how do I get there? I don't think I'm advanced enough to join an open source project, which seems to be suggested often (though I'd love to) and I've looked at other similar questions on here (like this one) but even then I don't think that'd work for me.. firstly, could somebody try give me some commonly used frameworks etc and how and what they are used for? Where would be a good place to start? How did you get started in using the things you do? Or perhaps you think I'm going down the wrong route. Should I learn another language, and just wait until the moment occurs where it's clear what I should be doing? I'm only in the first year of my degree, so far we've lightly covered Haskell and Java, and I've done a little HTML and CSS in my free time. I know that next year we cover python, so perhaps I should just wait till then and see if I prefer that? I feel like I also risk learning something in depth and then never using it... I suppose I'm also asking for personal experiences; was there a point where you felt you'd exceeded the basic grasp of a language (does not necessarily have to be Java related) and reach a more "advanced" level? I guess I'll put subjective tag on this, but really I just want to know how to get beyond the basic understanding of a language.

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• How to create refresh statements for TableAdapter objects in Visual Studio?

  - by Mark Wilkins

  I am working on developing an ADO.NET data provider and an associated DDEX provider. I am unable to convince the Visual Studio TableAdapater Configuration Wizard to generate SQL statements to refresh the data table after inserts and updates. It generates the insert and delete statements but will not produce the select statements to do the refresh. The functionality referred to can be accessed by dropping a table from the Server Explorer (inside Visual Studio) onto a DataSet (e.g., DataSet1.xsd). It creates a TableAdapter object and configures SELECT, UPDATE, DELETE, and INSERT statements. If you right click on the TableAdapter object, the context menu has a “Configure” option that starts the “TableAdapter Configuration Wizard”. The first dialog of that wizard has an Advanced Options button, which leads to an option titled “Refresh the data table”. When used with SQL Server tables, that option causes a statement of the form “select field1, field2, …” to be added on to the end of the commands for the TableAdapter’s InsertCommand and UpdateCommand. Do you have any idea what type property or interface might need to be exposed from the DDEX provider (or maybe the ADO.NET data provider) in order to make Visual Studio add those refresh statements to the update/insert commands? The MSDN documentation for the Advanced SQL Generation Options Dialog Box has a note stating, “Refreshing the data table is only supported on databases that support batching of SQL statements.” This seems to imply that a .NET data provider might need to expose some property indicating such behavior is supported. But I cannot find it. Any ideas?

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• How to prevent parallel builds per build configuration across multiple Build Agents

  - by vanslly

  I have many build configurations in TeamCity, each servicing a large project. In the past if a build is kicked off the Build Agent could be busy for up to 20min! In order to improve throughput I installed a second Build Agent on the same machine such that if a build run is kicked off by say Build Agent 1 and it is busy for 20min and someone from another project makes a change then Build Agent 2 can do the build for the other project without needing to wait on the current build run to finish. All was well until two successive check-ins resulted in both Build Agents running a build for a single build configuration in parallel. Since some resources are shared, IIS directories & databases, I don't want a single build configuration to run on both Build Agents in parallel. How can I ensure a build isn't triggered if a build is currently running for that build configuration on a different build agent? One way seems to involve environmental variables and ensuring a 50/50 split by Build Agent in terms of build configuration compatibility, but that seems a little clunky.

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• Help to restructure my Doc/View more correctly

  - by Harvey

  Edited by OP. My program is in need of a lot of cleanup and restructuring. In another post I asked about leaving the MFC DocView framework and going to the WinProc & Message Loop way (what is that called for short?). Well at present I am thinking that I should clean up what I have in Doc View and perhaps later convert to non-MFC it that even makes sense. My Document class currently has almost nothing useful in it. I think a place to start is the InitInstance() function (posted below). In this part: POSITION pos=pDocTemplate->GetFirstDocPosition(); CLCWDoc *pDoc=(CLCWDoc *)pDocTemplate->GetNextDoc(pos); ASSERT_VALID(pDoc); POSITION vpos=pDoc->GetFirstViewPosition(); CChildView *pCV=(CChildView *)pDoc->GetNextView(vpos); This seem strange to me. I only have one doc and one view. I feel like I am going about it backwards with GetNextDoc() and GetNextView(). To try to use a silly analogy; it's like I have a book in my hand but I have to look up in it's index to find out what page the Title of the book is on. I'm tired of feeling embarrassed about my code. I either need correction or reassurance, or both. :) Also, all the miscellaneous items are in no particular order. I would like to rearrange them into an order that may be more standard, structured or straightforward. ALL suggestions welcome! BOOL CLCWApp::InitInstance() { InitCommonControls(); if(!AfxOleInit()) return FALSE; // Initialize the Toolbar dll. (Toolbar code by Nikolay Denisov.) InitGuiLibDLL(); // NOTE: insert GuiLib.dll into the resource chain SetRegistryKey(_T("Real Name Removed")); // Register document templates CSingleDocTemplate* pDocTemplate; pDocTemplate = new CSingleDocTemplate( IDR_MAINFRAME, RUNTIME_CLASS(CLCWDoc), RUNTIME_CLASS(CMainFrame), RUNTIME_CLASS(CChildView)); AddDocTemplate(pDocTemplate); // Parse command line for standard shell commands, DDE, file open CCmdLineInfo cmdInfo; ParseCommandLine(cmdInfo); // Dispatch commands specified on the command line // The window frame appears on the screen in here. if (!ProcessShellCommand(cmdInfo)) { AfxMessageBox("Failure processing Command Line"); return FALSE; } POSITION pos=pDocTemplate->GetFirstDocPosition(); CLCWDoc *pDoc=(CLCWDoc *)pDocTemplate->GetNextDoc(pos); ASSERT_VALID(pDoc); POSITION vpos=pDoc->GetFirstViewPosition(); CChildView *pCV=(CChildView *)pDoc->GetNextView(vpos); if(!cmdInfo.m_Fn1.IsEmpty() && !cmdInfo.m_Fn2.IsEmpty()) { pCV->OpenF1(cmdInfo.m_Fn1); pCV->OpenF2(cmdInfo.m_Fn2); pCV->DoCompare(); // Sends a paint message when complete } // enable file manager drag/drop and DDE Execute open m_pMainWnd->DragAcceptFiles(TRUE); m_pMainWnd->ShowWindow(SW_SHOWNORMAL); m_pMainWnd->UpdateWindow(); // paints the window background pCV->bDoSize=true; //Prevent a dozen useless size calculations return TRUE; } Thanks

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• What is a good programming language/environment for Linux database applications?

  - by Dkellygb

  I could use some advice on my move from the Windows world to Linux. For my business, I have used VB6 and Microsoft Access with both Access databases and SQL server in the past. The easy to use forms, report writers and programming language were perfect for CRUD apps and analysis for our small hotel/restaurant business. After using Linux at home for some time I would like to convert our small business. Our server is already a Linux box using Samba. I am happy with the OpenOffice.org applications instead of Microsoft Office. The only thing which is holding me back is a desktop database application where I can develop the forms and reports we require. Base does not seem to be up to the job yet from my experience. I would like something like VB.Net with visual studio (express) but I would like to avoid Mono – I just don’t see the point of it. (You can correct me if I’m wrong.) But a good collection of forms, controls and a good report writer would be ideal. I have looked at web based stuff like Ruby on Rails, but I think a webserver for our 5 pc network is overkill. I don’t mind running a proper database on our Ubuntu 9.10 server. I may have exposed a few prejudices above but my mind is open. Any thoughts?

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• What algorithm should i follow to retrieve data in the prescribed format?

  - by Prateek

  I have to retrieve data from a database in which tables are consisting of fields like "ttc, rm, atc and lta" namely. Actually these values are stored on daily basis with a 15 min interval like From_time to_time ttc rm atc lta 00:00 00:15 45 10 35 25, 00:15 00:30 35 10 25 25 and so on .. These values are stored for every day of every month and i want it to be previewed in the prescribed format then what algorithm should i follow. I am confused about how to do comparisons for a format like below mentioned. The format is at this link https://drive.google.com/a/itbhu.ac.in/file/d/0B_J0Ljq64i4Za2J1V0lvbDZ4eGc/edit?usp=sharing To be specific once again, my question is, I have to prepare a report from the retrieved data which is being stored in the databases as explained above. But the report which is going to be prepared will be of entire month. So, to say the least, there may be cases that for two particular days the value of "ttc" would be same for some time so i want it to be listed together (as shown in format). And the confusing part is any of the values "ttc", "rm", "atc", "lta" can be same for any particular interval. So what algorithm should i follow for such comparisons. And if still any query with question, u can ask your doubt. Thanks

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• Why should I use Entity Framework over Linq2SQL ...

  - by Refracted Paladin

  To be clear, I am not asking for a side by side comparision which has already been asked Ad Nauseum here on SO. I am also Not asking if Linq2Sql is dead as I don't care. What I am asking is this.... I am building internal apps only for a non-profit organization. I am the only developer on staff. We ALWAYS use SQL Server as our Database backend. I design and build the Databases as well. I have used L2S successfully a couple of times already. Taking all this into consideration can someone offer me a compelling reason to use EF instead of L2S? I was at Code Camp this weekend and after an hour long demonstration on EF, all of which I could have done in L2S, I asked this same question. The speakers answer was, "L2S is dead..." Very well then! NOT! (see here) I understand EF is what MS WANTS us to use in the future(see here) and that it offers many more customization options. What I can't figure out is if any of that should, or does, matter for me in this environment. One particular issue we have here is that I inherited the Core App which was built on 4 different SQL Data bases. L2S has great difficulty with this but when I asked the aforementioned speaker if EF would help me in this regard he said "No!"

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• PHP: Writing non-english characters to XML - encoding problem

  - by Dean

  Hello, I wrote a small PHP script to edit the site news XML file. I used DOM to manipulate the XML (Loading, writing, editing). It works fine when writing English characters, but when non-English characters are written, PHP throws an error when trying to load the file. If I manually type non-English characters into the file - it's loaded perfectly fine, but if PHP writes the non-English characters the encoding goes wrong, although I specified the utf-8 encoding. Any help is appreciated. Errors: Warning: DOMDocument::load() [domdocument.load]: Entity 'times' not defined in filepath Warning: DOMDocument::load() [domdocument.load]: Input is not proper UTF-8, indicate encoding ! Bytes: 0x91 0x26 0x74 0x69 in filepath Here are the functions responsible for loading and saving the file (self-explanatory): function get_tags_from_xml(){ // Load news entries from XML file for display $errors = Array(); if(!$xml_file = load_news_file()){ // Load file // String indicates error presence $errors = "file not found"; return $errors; } $taglist = $xml_file->getElementsByTagName("text"); return $taglist; } function set_news_lang(){ // Sets the news language global $news_lang; if($_POST["news-lang"]){ $news_lang = htmlentities($_POST["news-lang"]); } elseif($_GET["news-lang"]){ $news_lang = htmlentities($_GET["news-lang"]); } else{ $news_lang = "he"; } } function load_news_file(){ // Load XML news file for proccessing, depending on language global $news_lang; $doc = new DOMDocument('1.0','utf-8'); // Create new XML document $doc->load("news_{$news_lang}.xml"); // Load news file by language $doc->formatOutput = true; // Nicely format the file return $doc; } function save_news_file($doc){ // Save XML news file, depending on language global $news_lang; $doc->saveXML($doc->documentElement); $doc->save("news_{$news_lang}.xml"); } Here is the code for writing to XML (add news): <?php ob_start()?> <?php include("include/xml_functions.php")?> <?php include("../include/functions.php")?> <?php get_lang();?> <?php //TODO: ADD USER AUTHENTICATION! if(isset($_POST["news"]) && isset($_POST["news-lang"])){ set_news_lang(); $news = htmlentities($_POST["news"]); $xml_doc = load_news_file(); $news_list = $xml_doc->getElementsByTagName("text"); // Get all existing news from file $doc_root_element = $xml_doc->getElementsByTagName("news")->item(0); // Get the root element of the new XML document $new_news_entry = $xml_doc->createElement("text",$news); // Create the submited news entry $doc_root_element->appendChild($new_news_entry); // Append submited news entry $xml_doc->appendChild($doc_root_element); save_news_file($xml_doc); header("Location: /cpanel/index.php?lang={$lang}&news-lang={$news_lang}"); } else{ header("Location: /cpanel/index.php?lang={$lang}&news-lang={$news_lang}"); } ?> <?php ob_end_flush()?>

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• question about MySQL database migration

  - by WilliamLou

  Hi there: If I have a MySQL database with several tables on a live server, now I would like to migrate this database to another server. Of course, the migration I mean here involves some database tables, for example: add some new columns to several tables, add some new tables etc.. Now, the only method I can think of is to use some php/python(two scripts I know) script, connect two databases, dump the data from the old database, and then write into the new database. However, this method is not efficient at all. For example: in old database, table A has 28 columns; in new database, table A has 29 columns, but the extra column will have default value 0 for all the old rows. My script still needs to dump the data row by row and insert each row into the new database. Is there any tools or a better method than writing a script yourself? Here, I dont need to worry about multithread writing problems etc.., I mean the old database will be down (not open to public usage etc.., only for upgrade ) for a while. Thanks!!

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• Database Error Handling: What if You have to Call Outside service and the Transaction Fails?

  - by Ngu Soon Hui

  We all know that we can always wrap our database call in transaction ( with or without a proper ORM), in a form like this: $con = Propel::getConnection(EventPeer::DATABASE_NAME); try { $con->begin(); // do your update, save, delete or whatever here. $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } This way would guarantee that if the transaction fails, the database is restored to the correct status. But the problem is that let's say when I do a transaction, in addition to that transaction, I need to update another database ( an example would be when I update an entry in a column in databaseA, another entry in a column in databaseB must be updated). How to handle this case? Let's say, this is my code, I have three databases that need to be updated ( dbA, dbB, dbc): $con = Propel::getConnection("dbA"); try { $con->begin(); // update to dbA // update to dbB //update to dbc $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } If dbc fails, I can rollback the dbA but I can't rollback dbb. I think this problem should be database independent. And since I am using ORM, this should be ORM independent as well. Update: Some of the database transactions are wrapped in ORM, some are using naked PDO, oledb ( or whatever bare minimum language provided database calls). So my solution has to take care this. Any idea?

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• Add options to select box without Internet Explorer closing the box?

  - by Paul Colby

  Hi, I'm trying to build a web page with a number of drop-down select boxes that load their options asynchronously when the box is first opened. This works very well under Firefox, but not under Internet Explorer. Below is a small example of what I'm trying to achieve. Basically, there is a select box (with the id "selectBox"), which contains just one option ("Any"). Then there is an onmousedown handler that loads the other options when the box is clicked. <html> <head> <script type="text/javascript"> function appendOption(select,option) { try { selectBox.add(option,null); // Standards compliant. } catch (e) { selectBox.add(option); // IE only version. } } function loadOptions() { // Simulate an AJAX request that will call the // loadOptionsCallback function after 500ms. setTimeout(loadOptionsCallback,500); } function loadOptionsCallback() { var selectBox = document.getElementById('selectBox'); var option = document.createElement('option'); option.text = 'new option'; appendOption(selectBox,option); } </script> </head> <body> <select id="selectBox" onmousedown="loadOptions();"> <option>Any</option> </select> </body> </html> The desired behavior (which Firefox does) is: the user see's a closed select box containing "Any". the user clicks on the select box. the select box opens to reveal the one and only option ("Any"). 500ms later (or when the AJAX call has returned) the dropped-down list expands to include the new options (hard coded to 'new option' in this example). So that's exactly what Firefox does, which is great. However, in Internet Explorer, as soon as the new option is added in "4" the browser closes the select box. The select box does contain the correct options, but the box is closed, requiring the user to click to re-open it. So, does anyone have any suggestions for how I can load the select control's options asynchronously without IE closing the drop-down box? I know that I can load the list before the box is even clicked, but the real form I'm developing contains many such select boxes, which are all interrelated, so it will be much better for both the client and server if I can load each set of options only when needed. Also, if the results are loaded synchronously, before the select box's onmousedown handler completes, then IE will show the full list as expected - however, synchronous loading is a bad idea here, since it will completely "lock" the browser while the network requests are taking place. Finally, I've also tried using IE's click() method to open the select box once the new options have been added, but that does not re-open the select box. Any ideas or suggestions would be really appreciated!! :) Thanks! Paul.

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• What ORM for .NET should I use?

  - by eKek0

  I'm relatively new to .NET and have being using Linq2Sql for a almost a year, but it lacks some of the features I'm looking for now. I'm going to start a new project in which I want to use an ORM with the following characteristics: It has to be very productive, I don't want to be dealing with the access layer to save or retrieve objects from or to the database, but it should allows me to easily tweak any object before actually commit it to the database; also it should allows me to work easily with a changing database schema It should allows me to extend the objects mapped from the database, for example to add virtual attributes to them (virtual columns to a table) It has to be (at least almost) database agnostic, it should allows me to work with different databases in a transparent way It has to have not so much configuration or must be based on conventions to make it work It should allows me to work with Linq So, do you know any ORM that I could use? Thank you for your help. EDIT I know that an option is to use NHibernate. This appears as the facto standard for enterprise level applications, but also it seems that is not very productive because its deep learning curve. In other way, I have read in some other post here in SO that it doesn't integrate well with Linq. Is all of that true?

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• What are the options for overriding Django's cascading delete behaviour?

  - by Tom

  Django models generally handle the ON DELETE CASCADE behaviour quite adequately (in a way that works on databases that don't support it natively.) However, I'm struggling to discover what is the best way to override this behaviour where it is not appropriate, in the following scenarios for example: ON DELETE RESTRICT (i.e. prevent deleting an object if it has child records) ON DELETE SET NULL (i.e. don't delete a child record, but set it's parent key to NULL instead to break the relationship) Update other related data when a record is deleted (e.g. deleting an uploaded image file) The following are the potential ways to achieve these that I am aware of: Override the model's delete() method. While this sort of works, it is sidestepped when the records are deleted via a QuerySet. Also, every model's delete() must be overridden to make sure Django's code is never called and super() can't be called as it may use a QuerySet to delete child objects. Use signals. This seems to be ideal as they are called when directly deleting the model or deleting via a QuerySet. However, there is no possibility to prevent a child object from being deleted so it is not usable to implement ON CASCADE RESTRICT or SET NULL. Use a database engine that handles this properly (what does Django do in this case?) Wait until Django supports it (and live with bugs until then...) It seems like the first option is the only viable one, but it's ugly, throws the baby out with the bath water, and risks missing something when a new model/relation is added. Am I missing something? Any recommendations?

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• General SQL Server query performance

  - by Kiril

  Hey guys, This might be stupid, but databases are not my thing :) Imagine the following scenario. A user can create a post and other users can reply to his post, thus forming a thread. Everything goes in a single table called Posts. All the posts that form a thread are connected with each other through a generated key called ThreadID. This means that when user #1 creates a new post, a ThreadID is generated, and every reply that follows has a ThreadID pointing to the initial post (created by user #1). What I am trying to do is limit the number of replies to let's say 20 per thread. I'm wondering which of the approaches bellow is faster: 1 I add a new integer column (e.x. Counter) to Posts. After a user replies to the initial post, I update the initial post's Counter field. If it reaches 20 I lock the thread. 2 After a user replies to the initial post, I select all the posts that have the same ThreadID. If this collection has more than 20 items, I lock the thread. For further information: I am using SQL Server database and Linq-to-SQL entity model. I'd be glad if you tell me your opinions on the two approaches or share another, faster approach. Best Regards, Kiril

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• Atomic int writes on file

  - by Waneck

  Hello! I'm writing an application that will have to be able to handle many concurrent accesses to it, either by threads as by processes. So no mutex'es or locks should be applied to this. To make the use of locks go down to a minimum, I'm designing for the file to be "append-only", so all data is first appended to disk, and then the address pointing to the info it has updated, is changed to refer to the new one. So I will need to implement a small lock system only to change this one int so it refers to the new address. How is the best way to do it? I was thinking about maybe putting a flag before the address, that when it's set, the readers will use a spin lock until it's released. But I'm afraid that it isn't at all atomic, is it? e.g. a reader reads the flag, and it is unset on the same time, a writer writes the flag and changes the value of the int the reader may read an inconsistent value! I'm looking for locking techniques but all I find is either for thread locking techniques, or to lock an entire file, not fields. Is it not possible to do this? How do append-only databases handle this? Thanks! Cauê

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• Why am I getting 'Argument count mismatch' error here?

  - by Leon

  I have a Document class, Intro class and Nav class. The Intro class runs first, then sends a custom dispatch event to run the Nav class, but I'm getting this error: removed Intro ArgumentError: Error #1063: Argument count mismatch on com.secrettowriting.StanPlayer.ui::Navigation/addNav(). Expected 0, got 1. at flash.events::EventDispatcher/dispatchEventFunction() at flash.events::EventDispatcher/dispatchEvent() at com.secrettowriting.StanPlayer.display::Intro/removeIntro() at flash.utils::Timer/_timerDispatch() at flash.utils::Timer/tick() The addNav function in the Navigation class should expect 0 arguments/variables and I'm not sending any arguments/variables to it, which is why I'm confused as to why it's saying I'm getting 1. My Document Class: public function HomePlayer():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); stage.scaleMode = StageScaleMode.NO_SCALE; stage.align = StageAlign.TOP_LEFT; // Use when Live //videoURL = this.loaderInfo.parameters.theVIDEO; // Get the Video URL from HTML // Remove when video testing ready videoURL = "videos/WhatDifferentiatesUs.flv"; drawNav(); drawIntro(); } private function drawIntro():void { intro = new Intro(); intro.drawIntro(); intro.addEventListener("onComplete", nav.addNav); stage.addChild(intro); } private function drawNav():void { nav = new Navigation(); nav.drawNav(); stage.addChild(nav); } Intro Class: Public function Intro():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); } public function drawIntro():void { introMov = new IntroMov(); introMov.alpha = 0; addChild(introMov); TweenLite.to(introMov, 3, {alpha:1}); // Timer introFader = new Timer(INTRO_DELAY); introFader.addEventListener(TimerEvent.TIMER, fadeIntro); introFader.start(); introRemover = new Timer(INTRO_DELAY); introRemover.addEventListener(TimerEvent.TIMER, removeIntro); } private function fadeIntro(e:TimerEvent):void { if (i < 30){ i++ } else if (i == 30){ TweenLite.to(introMov, 1.5, {alpha:0}); introFader.removeEventListener(TimerEvent.TIMER, fadeIntro); introRemover.start(); } } private function removeIntro(e:TimerEvent):void { if (n < 10){ n++ } else if (n == 10){ introRemover.removeEventListener(TimerEvent.TIMER, removeIntro); removeChild(introMov); trace("removed Intro"); dispatchEvent (new CustomEvent(CustomEvent.COMPLETE, {})); // ? Intro to Navigation } } Navigation Class functions: public function drawNav():void { weAreA = new WeAreA(); weAreA.alpha = 0; weAreA.x = 20; weAreA.y = 35; introText = new IntroText(); introText.alpha = 0; introText.x = 20; introText.y = 124; chooseAVideo = new ChooseAVideo(); chooseAVideo.alpha = 0; chooseAVideo.x = 20; chooseAVideo.y = 336; } public function addNav():void { addChild(weAreA); addChild(introText); addChild(chooseAVideo); TweenLite.to(weAreA, 2, {alpha:1}); TweenLite.to(introText, 3, {alpha:1}); TweenLite.to(introText, 3, {alpha:1}); }

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• How can I access mainframe data with .Net applications and SQL Queries?

  - by orandov

  We have a large amount of data stored on an IBM mainframe using VSAM files. A lot of this data is dropped on the network every night in the form of text files to be processed and dumped into FoxPro and SQL Server databases. There are also many text files produced nightly by custom applications that get uploaded to the mainframe to keep everything in sync. Keeping the everything in sync is very tricky, to say the least. We are not getting rid of the mainframe any time soon and we would like to replace all the nightly batch processing with real time access to the mainframe data. We would like to be able to: Read data directly from the mainframe and produce reports based on it. Possibly using SQL queries. Read and Write data from custom .Net applications. We are not looking for a new platform to interface with the mainframe like Information Builders offers. We don't want to build application modules or reports with new "Business Intelligence" tools. We already know how to generate reports and write custom applications using SQL,.Net, Visual Studio, etc. All we are looking for is some sort of adapter to connect to our mainframe data. Any ideas are appreciated.

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• Parsing xml file that comes in as one object per line

  - by Casey

  I haven't been here in so long, I forgot my prior account! Anyways, I am working on parsing an xml document that comes in ugly. It is for banking statements. Each line is a <statement>all tags</statement>. Now, what I need to do is read this file in, and parse the XML document at the same time, while formatting it more human readable too. Point beeing, Original input looks like this: <statement><accountHeader><fiAddress></fiAddress><accountNumber></accountNumber><startDate>20140101</startDate><endDate>20140228</endDate><statementGroup>1</statementGroup><sortOption>0</sortOption><memberBranchCode>1</memberBranchCode><memberName></memberName><jointOwner1Name></jointOwner1Name><jointOwner2Name></jointOwner2Name></summary></statement> <statement><accountHeader><fiAddress></fiAddress><accountNumber></accountNumber><startDate>20140101</startDate><endDate>20140228</endDate><statementGroup>1</statementGroup><sortOption>0</sortOption><memberBranchCode>1</memberBranchCode><memberName></memberName><jointOwner1Name></jointOwner1Name><jointOwner2Name></jointOwner2Name></summary></statement> <statement><accountHeader><fiAddress></fiAddress><accountNumber></accountNumber><startDate>20140101</startDate><endDate>20140228</endDate><statementGroup>1</statementGroup><sortOption>0</sortOption><memberBranchCode>1</memberBranchCode><memberName></memberName><jointOwner1Name></jointOwner1Name><jointOwner2Name></jointOwner2Name></summary></statement> I need the final output to be as follows: <statement> <name></name> <address></address> </statement> This is fine and dandy. I am using the following "very slow considering 5.1 million lines, 254k data file, and about 60k statements takes around 8 minutes". foreach(String item in lines) { XElement xElement = XElement.Parse(item); sr.WriteLine(xElement.ToString().Trim()); } Then when the file is formatted this is what sucks. I need to check every single tag in transaction elements, and if a tag is missing that could be there, I have to fill it in. Our designer software will default prior values in if a tag is possible, and the current objects does not have. It defaults in the value of a prior one that was not Null. "I know, and they swear up and down it is not a bug... ok?" So, that is also taking about 5 to 10 minutes. I need to break all this down, and find a faster method for working with the initial XML. This is a preprocess action, and cannot take that long if not necessary. It just seems redundant. Is there a better way to parse the XML, or is this the best I can do? I parse the XML, write to a temp file, and then read that file in, to the output file inserting the missing tags. 2 IO runs for one process. Yuck.

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• MySQL FULLTEXT not working

  - by Ross

  I'm attempting to add searching support for my PHP web app using MySQL's FULLTEXT indexes. I created a test table (using the MyISAM type, with a single text field a) and entered some sample data. Now if I'm right the following query should return both those rows: SELECT * FROM test WHERE MATCH(a) AGAINST('databases') However it returns none. I've done a bit of research and I'm doing everything right as far as I can tell - the table is a MyISAM table, the FULLTEXT indexes are set. I've tried running the query from the prompt and from phpMyAdmin, with no luck. Am I missing something crucial? UPDATE: Ok, while Cody's solution worked in my test case it doesn't seem to work on my actual table: CREATE TABLE IF NOT EXISTS `uploads` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` text NOT NULL, `size` int(11) NOT NULL, `type` text NOT NULL, `alias` text NOT NULL, `md5sum` text NOT NULL, `uploaded` datetime NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ; And the data I'm using: INSERT INTO `uploads` (`id`, `name`, `size`, `type`, `alias`, `md5sum`, `uploaded`) VALUES (1, '04 Sickman.mp3', 5261182, 'audio/mp3', '1', 'df2eb6a360fbfa8e0c9893aadc2289de', '2009-07-14 16:08:02'), (2, '07 Dirt.mp3', 5056435, 'audio/mp3', '2', 'edcb873a75c94b5d0368681e4bd9ca41', '2009-07-14 16:08:08'), (3, 'header_bg2.png', 16765, 'image/png', '3', '5bc5cb5c45c7fa329dc881a8476a2af6', '2009-07-14 16:08:30'), (4, 'page_top_right2.png', 5299, 'image/png', '4', '53ea39f826b7c7aeba11060c0d8f4e81', '2009-07-14 16:08:37'), (5, 'todo.txt', 392, 'text/plain', '5', '7ee46db77d1b98b145c9a95444d8dc67', '2009-07-14 16:08:46'); The query I'm now running is: SELECT * FROM `uploads` WHERE MATCH(name) AGAINST ('header' IN BOOLEAN MODE) Which should return row 3, header_bg2.png. Instead I get another empty result set. My options for boolean searching are below: mysql> show variables like 'ft_%'; +--------------------------+----------------+ | Variable_name | Value | +--------------------------+----------------+ | ft_boolean_syntax | + -><()~*:""&| | | ft_max_word_len | 84 | | ft_min_word_len | 4 | | ft_query_expansion_limit | 20 | | ft_stopword_file | (built-in) | +--------------------------+----------------+ 5 rows in set (0.02 sec) "header" is within the word length restrictions and I doubt it's a stop word (I'm not sure how to get the list). Any ideas?

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• Selecting a whole database over an individual table to output to file

  - by Daniel Wrigley

  :::::::: EDIT :::::::: New code for people to have a look at, one question I have with this is where do I set were the *.gz file is saved? $backupFile = $dbname . date("Y-m-d-H-i-s") . '.gz'; $command = "mysqldump --opt -h $dbhost -u $dbuser -p $dbpass $dbname | gzip > $backupFile"; system($command); Also why the hell can you not reply yo your own post with answering it? :( :::::::: EDIT :::::::: Ok Im having trouble finding out how to select a full database for backup as an *.sql file rather than only an individual table. On the localhost I have several databases with one named "foo" and it is that which I want to backup and not any of the individual tables inside the database "foo". The code to connect to the database; //Database Information $dbhost = "localhost"; $dbname = "foo"; $dbuser = "bar"; $dbpass = "rulz"; //Connect to database mysql_connect ($dbhost, $dbuser, $dbpass) or die("Could not connect: ".mysql_error()); mysql_select_db($dbname) or die(mysql_error()); The code to backup the database; // Grab the time to know when this post was submitted $time = date('Y-m-d-H-i-s'); $tableName = 'foo'; $backupFile = '/sql/backup/'. $time .'.sql'; $query = "SELECT * INTO OUTFILE '". $backupFile ."' FROM ". $tableName .""; $result = mysql_query($query)or die("Database query died: " . mysql_error()); My brain is hurting near to the end of the day so no doubts i've missed something out very obvious. Thanks in advance to anyone helping me out.

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• Craziest JavaScript behavior I've ever seen

  - by Dan Ray

  And that's saying something. This is based on the Google Maps sample for Directions in the Maps API v3. <html> <head> <meta name="viewport" content="initial-scale=1.0, user-scalable=no"/> <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> <title>Google Directions</title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script type="text/javascript"> var directionDisplay; var directionsService = new google.maps.DirectionsService(); var map; function initialize() { directionsDisplay = new google.maps.DirectionsRenderer(); var myOptions = { zoom:7, mapTypeId: google.maps.MapTypeId.ROADMAP } map = new google.maps.Map(document.getElementById("map_canvas"), myOptions); directionsDisplay.setMap(map); directionsDisplay.setPanel(document.getElementById("directionsPanel")); } function render() { var start; if(navigator.geolocation) { navigator.geolocation.getCurrentPosition(function(position) { start = new google.maps.LatLng(position.coords.latitude,position.coords.longitude); }, function() { handleNoGeolocation(browserSupportFlag); }); } else { // Browser doesn't support Geolocation handleNoGeolocation(); } alert("booga booga"); var end = '<?= $_REQUEST['destination'] ?>'; var request = { origin:start, destination:end, travelMode: google.maps.DirectionsTravelMode.DRIVING }; directionsService.route(request, function(response, status) { if (status == google.maps.DirectionsStatus.OK) { directionsDisplay.setDirections(response); } }); } </script> </head> <body style="margin:0px; padding:0px;" onload="initialize()"> <div><div id="map_canvas" style="float:left;width:70%; height:100%"></div> <div id="directionsPanel" style="float:right;width:30%;height 100%"></div> <script type="text/javascript">render();</script> </body> </html> See that "alert('booga booga')" in there? With that in place, this all works fantastic. Comment that out, and var start is undefined when we hit the line to define var request. I discovered this when I removed the alert I put in there to show me the value of var start, and it quit working. If I DO ask it to alert me the value of var start, it tells me it's undefined, BUT it has a valid (and accurate!) value when we define var request a few lines later. I'm suspecting it's a timing issue--like an asynchronous something is having time to complete in the background in the moment it takes me to dismiss the alert. Any thoughts on work-arounds?

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