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  • hibernate column uniqueness question

    - by Seth
    I'm still in the process of learning hibernate/hql and I have a question that's half best practices question/half sanity check. Let's say I have a class A: @Entity public class A { @Id @GeneratedValue(strategy=GenerationType.AUTO) private Long id; @Column(unique=true) private String name = ""; //getters, setters, etc. omitted for brevity } I want to enforce that every instance of A that gets saved has a unique name (hence the @Column annotation), but I also want to be able to handle the case where there's already an A instance saved that has that name. I see two ways of doing this: 1) I can catch the org.hibernate.exception.ConstraintViolationException that could be thrown during the session.saveOrUpdate() call and try to handle it. 2) I can query for existing instances of A that already have that name in the DAO before calling session.saveOrUpdate(). Right now I'm leaning towards approach 2, because in approach 1 I don't know how to programmatically figure out which constraint was violated (there are a couple of other unique members in A). Right now my DAO.save() code looks roughly like this: public void save(A a) throws DataAccessException, NonUniqueNameException { Session session = sessionFactory.getCurrentSession(); try { session.beginTransaction(); Query query = null; //if id isn't null, make sure we don't count this object as a duplicate if(obj.getId() == null) { query = session.createQuery("select count(a) from A a where a.name = :name").setParameter("name", obj.getName()); } else { query = session.createQuery("select count(a) from A a where a.name = :name " + "and a.id != :id").setParameter("name", obj.getName()).setParameter("name", obj.getName()); } Long numNameDuplicates = (Long)query.uniqueResult(); if(numNameDuplicates > 0) throw new NonUniqueNameException(); session.saveOrUpdate(a); session.getTransaction().commit(); } catch(RuntimeException e) { session.getTransaction().rollback(); throw new DataAccessException(e); //my own class } } Am I going about this in the right way? Can hibernate tell me programmatically (i.e. not as an error string) which value is violating the uniqueness constraint? By separating the query from the commit, am I inviting thread-safety errors, or am I safe? How is this usually done? Thanks!

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  • A leader election algorithm for an oriented hypercube

    - by mick
    I'm stuck with some problem where I have to design a leader election algorithm for an oriented hypercube. This should be done by using a tournament with a number of rounds equal to the dimension D of the hypercube. In each stage d, with 1 <= d < D two candidate leaders of neighbouring d-dimensional hypercubes should compete to become the single candidate leader of the (d+1)-dimensional hypercube that is the union of their respective hypercubes.

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  • NoSQL DB for .Net document-based database (ECM)

    - by Dane
    I'm halfway through coding a basic multi-tenant SaaS ECM solution. Each client has it's own instance of the database / datastore, but the .Net app is single instance. The documents are pretty much read only (i.e. an image archive of tiffs or PDFs) I've used MSSQL so far, but then started thinking this might be viable in a NoSQL DB (e.g. MongoDB, CouchDB). The basic premise is that it stores documents, each with their own particular indexes. Each tenant can have multiple document types. e.g. One tenant might have an invoice type, which has Customer ID, Invoice Number and Invoice Date. Another tenant might have an application form, which has Member Number, Application Number, Member Name, and Application Date. So far I've used the old method which Sharepoint (used?) to use, and created a document table which has int_field_1, int_field_2, date_field_1, date_field_2, etc. Then, I've got a "mapping" table which stores the customer specific index name, and the database field that will map to. I've avoided the key-value pair model in the DB due to volume of documents. This way, we can support multiple document types in the one table, and get reasonably high performance out of it, and allow for custom document type searches (i.e. user selects a document type, then they're presented with a list of search fields). However, a NoSQL DB might make this a lot simpler, as I don't need to worry about denormalizing the document. However, I've just got concerns about the rest of the data around a document. We store an "action history" against the document. This tracks views, whether someone emails the document from within the system, and other "future" functionality (e.g. faxing). We have control over the document load process, so we can manipulate the data however it needs to be to get it in the document store (e.g. assign unique IDs). Users will not be adding in their own documents, so we shouldn't need to worry about ACID compliance, as the documents are relatively static. So, my questions I guess : Is a NoSQL DB a good fit Is MongoDB the best for Asp.Net (I saw Raven and Velocity, but they're still kinda beta) Can I store a key for each document, and then store the action history in a MSSQL DB with this key? I don't need to do joins, it would be if a person clicks "View History" against a document. How would performance compare between the two (NoSQL DB vs denormalized "document" table) Volumes would be up to 200,000 new documents per month for a single tenant. My current scaling plan with the SQL DB involves moving the SQL DB into a cluster when certain thresholds are reached, and then reviewing partitioning and indexing structures.

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  • Improve drawingvisual render's speed

    - by Michael Hao
    I create my own FrameworkElement and override VisualChildrenCount{get;} and GetVisualChild(int index) by returning my own DrawingVisual collection instance.I have override OnRender . I will add 20-50 DrawingVisuals in this FrameworkElement ,every DrawingVisual will have 2000 line segments.The logic value of these points between 0 to 60000.when I zoom into 1:1 the FrameworkElement 's Height will be 60000, the rending time will be 15 minutes!! How do I improve the rending performance ?

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  • Which MySQL Frontend shows foreign rows?

    - by Jeremy Rudd
    I once came across a MySQL Frontend app that displayed foreign linked rows within the parent row, if for instance the Events table has a foreign key to the Students table: Student ID Name DOB -- ---- --------- [+] 22 Bob 25-1-1984 [-] 21 Jane 25-1-1982 Event ID Student-ID Name Time -- ---------- ---- --------- 1 21 Event A 05:50 1 21 Event B 17:20 [+] 20 Jack 25-1-1980

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  • How to 'assign' a value to an output reg in Verilog?

    - by Rafael Almeida
    ( insert really basic question disclaimer here ) More specifically, I have the following declaration: output reg icache_ram_rw And in some point of the code I need to put the zero value in this reg. Here's what I've tried and the outcomes: assign icache_ram_rw = 1'b0; ( declarative lvalue or port sink reg icache_ram_rw must be a wire ) icache_ram_rw <= 1'b0; ( instance gate/name for type "icache_ram_rw" expected - <= read ) How do I do it after all?!

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  • how to move a postgres schema via file operations ?

    - by Jerome WAGNER
    Hello, I have a schema schema1 in a postgres database A. I want to have a duplicate of this schema (model + data) in database B under the name schema2. What are my options ? I currently : * dump schema1 from database A * sed my way through schema renaming in the dump : schema1 becomes schema2 * restore schema2 in database B but I am looking for a more efficient procedure. For instance, via direct file operations on postgres binary files. Thanks for your help Jerome Wagner

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  • will_paginate with named_scopes

    - by Lowgain
    I'm using will_paginate for pagination, which has been working well so far, except for this one thing. If I try to paginate a scope, for instance class User < ActiveRecord::Base named_scope :scope, lambda { etc } end User.scope.paginate({:page => params[:page], :per_page => 10}) That will tell me paginate is an undefined method. I'd rather not have to use a second solution for only this scope, is there something I can do here?

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  • error while soap request call

    - by Jayshree
    Hello. I am trying to make a soap call. Its a very basic call wit Welcome User output. The return value is in xml format. and i am getting the following error. can anyone plz tell me what this error means. The following code shows the soap request and post request that i have made NSString *soapMessage = [NSString stringWithFormat: @"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n" "<soap:Body>\n" "<WelcomeXML xmlns=\"http://qa2.alliancetek.com/phpwebservice/index.php\">\n" "<name>" "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" "<message>\n" "<name>Hitesh</name>\n" "</message>\n" "</name>" "</WelcomeXML>\n" "</soap:Body>\n" "</soap:Envelope>\n"]; NSLog(@"%@",soapMessage); NSURL *url = [NSURL URLWithString:@"http://qa2.alliancetek.com/phpwebservice/index.php"]; NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url]; NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]]; [theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"]; [theRequest addValue: @"http://qa2.alliancetek.com/phpwebservice/index.php/WelcomeXML" forHTTPHeaderField:@"SOAPAction"]; [theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"]; [theRequest setHTTPMethod:@"POST"]; [theRequest setHTTPBody: [soapMessage dataUsingEncoding:NSUTF8StringEncoding]]; Following is the Error that i am getting : <?xml version="1.0" encoding="ISO-8859-1"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Body><SOAP-ENV:Fault><faultcode xsi:type="xsd:string">SOAP-ENV:Client</faultcode><faultactor xsi:type="xsd:string"></faultactor><faultstring xsi:type="xsd:string">error in msg parsing: XML error parsing SOAP payload on line 5: Reserved XML Name</faultstring><detail xsi:type="xsd:string"></detail></SOAP-ENV:Fault></SOAP-ENV:Body></SOAP-ENV:Envelope> plz help me. I have wasted 2 days on a simple code like this.

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  • Delphi Phrase Count

    - by Brad
    Does anyone know how to or have some code on counting the number of unique phrases in a document? (Single word, two word phrases, three word phrases). Thanks

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  • Executing Line/Multiple Lines Only in mySQL Query Browser

    - by David Bonnici
    I already used Microsoft SQL Server 2005 and found really easy to execute single/multiple lines of an sql query. Example: insert into tablea ($vala, $valb, $valc) values ($vala, $valb, $valc); insert into tableb ($vala, $valb, $valc) values ($vala, $valb, $valc); How can I execute the second part only? In MSSQL i will highlight the second insert statment and press F5. How can do this in mySQL?

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  • Jquery How to change url for every ajax respond

    - by fatih-kurt
    $(".blok").newWindow({ windowTitle:"Example1", ajaxURL:"Action.php?task=BlokDuzenleFormGetirBlokId="+$(".blok").attr('id') }); when first clicked on blok class a href, newWindow loads from data by $(".blok").attr('id'). Then every action sen same url to ajax, with not change. is there a way change url every single respond to call function by unique id parametre or anything like that.

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  • Correct mapping for SHChangeNotify in JNA

    - by user389658
    This is syntax for SHChangeNotify function from MSDN: void SHChangeNotify( LONG wEventId, UINT uFlags, __in_opt LPCVOID dwItem1, __in_opt LPCVOID dwItem2 ); I've to write its Java counterpart in Java Native Access [JNA], but this declaration seems to be wrong: public interface Shell32 extends com.sun.jna.platform.win32.Shell32 { public Shell32 INSTANCE = (Shell32) Native.loadLibrary(Shell32.class); void SHChangeNotify(long wEventId, int uFlags, Pointer dwItem1, Pointer dwItem2); } I got the following exception: Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'SHChangeNotify' Any idea how to write it correctly?

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  • Host a project on Github and Google Code

    - by Abhi Beckert
    Is it possible to have a project hosted on Github and google code? I've been using Google Code for years, and recently started playing with GitHub. I like GitHub a lot, but there's also a long list of Google Code features I really miss. Is it possible/feasible to host a single project on both? Can I use github as the primary repository for my source, but have all revisions automatically sent over to a git repository on Google Code?

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  • How can I know which Area my MVC controller action is being called in?

    - by kripto_ash
    I want to know how, from a controller action, I could identify the area in which the controller is in via the MVC framework (I mean, without making all controllers in a given area inherit from a base controller with that info). I'm particularly interested in the case of child actions (controller actions rendered via RenderAction), the area of the calling parent controller for instance. I'm using ASP .NET MVC 2.0 RTM

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  • How To Create Per-Request Singleton in Pylons?

    - by dave mankoff
    In our Pylons based web-app, we're creating a class that essentially provides some logging functionality. We need a new instance of this class for each http request that comes in, but only one per request. What is the proper way to go about this? Should we just create the object in middleware and store in in request.environ? Is there a more appropriate way to go about this?

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  • How can I determine which taskbar application/windows are requesting user attention

    - by Frederic
    I'd like to know how to get a list of the windows requiring user attention from the Windows taskbar. Windows requiring attention appear with a flashing orange color within the Windows taskbar. Un-focused MSN Messenger conversation windows are a good example of this behavior: they turn orange as soon as a remote user sends an instance message. My code targets the Windows 7 platform, but working on older Windows OS would be nice too.

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