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  • Catching constraint violations in JPA 2.0.

    - by Dennetik
    Consider the following entity class, used with, for example, EclipseLink 2.0.2 - where the link attribute is not the primary key, but unique nontheless. @Entity public class Profile { @Id private Long id; @Column(unique = true) private String link; // Some more attributes and getter and setter methods } When I insert records with a duplicate value for the link attribute, EclipseLink does not throw a EntityExistsException, but throws a DatabaseException, with the message explaining that the unique constraint was violated. This doesn't seem very usefull, as there would not be a simple, database independent, way to catch this exception. What would be the advised way to deal with this? A few things that I have considered are: Checking the error code on the DatabaseException - I fear that this error code, though, is the native error code for the database; Checking the existence of a Profile with the specific value for link beforehand - this obviously would result in an enormous amount of superfluous queries.

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  • delete in tableView..

    - by totato
    I just add this methods in .h file : - (IBAction)EditTable:(id)sender; - (IBAction)DeleteButtonAction:(id)sender; and in .m file : (IBAction)DeleteButtonAction:(id)sender{ [tableList removeLastObject]; [Table reloadData]; } (IBAction) EditTable:(id)sender{ if(self.editing) { [super setEditing:NO animated:NO]; [Table setEditing:NO animated:NO]; [Table reloadData]; [self.navigationItem.leftBarButtonItem setTitle:@"Edit"]; [self.navigationItem.leftBarButtonItem setStyle:UIBarButtonItemStylePlain]; } else { [super setEditing:YES animated:YES]; [Table setEditing:YES animated:YES]; [Table reloadData]; [self.navigationItem.leftBarButtonItem setTitle:@"Done"]; [self.navigationItem.leftBarButtonItem setStyle:UIBarButtonItemStyleDone]; } } when I run the program and click the delete button (red button) the program is stop ! whats the problem ? please any help ?

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  • Ruby class instance variables and inheritance

    - by rlandster
    I have a Ruby class called LibraryItem. I want to associate with every instance of this class an array of attributes. This array is long and looks something like ['title', 'authors', 'location', ...] Note that these attributes are not really supposed to be methods, just a list of attributes that a LibraryItem has. Next, I want to make a subclass of LibraryItem called LibraryBook that has an array of attributes that includes all the attributes of LibraryItem but will also include many more. Eventually I will want several subclasses of LibraryItem each with their own version of the array @attributes but each adding on to LibraryItem's @attributes (e.g., LibraryBook, LibraryDVD, LibraryMap, etc.). So, here is my attempt: class LibraryItem < Object class << self; attr_accessor :attributes; end @attributes = ['title', 'authors', 'location',] end class LibraryBook < LibraryItem @attributes.push('ISBN', 'pages'] end This does not work. I get the error undefined method `push' for nil:NilClass

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  • Better to use constructor or method factory pattern?

    - by devoured elysium
    I have a wrapper class for the Bitmap .NET class called BitmapZone. Assuming we have a WIDTH x HEIGHT bitmap picture, this wrapper class should serve the purpose of allowing me to send to other methods/classes itself instead of the original bitmap. I can then better control what the user is or not allowed to do with the picture (and I don't have to copy the bitmap lots of times to send for each method/class). My question is: knowing that all BitmapZone's are created from a Bitmap, what do you find preferrable? Constructor syntax: something like BitmapZone bitmapZone = new BitmapZone(originalBitmap, x, y, width, height); Factory Method Pattern: BitmapZone bitmapZone = BitmapZone.From(originalBitmap, x , y, width, height); Factory Method Pattern: BitmapZone bitmapZone = BitmapZone.FromBitmap(originalBitmap, x, y, width, height); Other? Why? Thanks

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  • How to perform different operations within Observer's update() in Java?

    - by Nazgulled
    I just started playing with Observable, Observer and it's update() method and I can't understand what should I do when different actions call notifyObservers(). I mean, my Observable class has a few different methods that call setChanged() and notifyObservers() in the end. Depending on the called method, some part of the UI (Swing) needs to be updated. However, there is only one update() method implemented in the Observer class. I though of passing something to the notifyObservers() method and then I can check the argument on update() but it doesn't seem feel like a good way to do it. Even if it did, what should I pass? A string with a short description of the action/method? And int, like an action/method code? Something else? What's the best way to handle this situation?

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  • File Upload in GWT in a Special Case

    - by Maksud
    I am doing a software for a document system. In this system when a user completes a document and want to save it, the document will be uploaded directly to server without the user action. This system uses COM/ActiveX to facilitate user using native editors. Ok, my problem is: suppose I have a file say d:/notepad.txt. Using classical method a user can browse the file and upload it. I can do that with apache commonio and GWT FormPanel and FileUpload. But if I know the filename (d:/notepad.txt), is there any way to upload the file directly to server without the user having to browse the file. I am currently doing this by the ActiveX componenet calling some HttpUpload methods with POST. But that does not maintain session. Thanks

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  • Strange profiling results: definitely non-bottleneck method pops up

    - by jkff
    I'm profiling a program using sampling profiling in YourKit and JProfiler, and also "manually" (I launch it and press Ctrl-Break several times to get thread dumps). All three methods give me extremely strange results: some tens of percents of time spent in a 3-line method that does not even do any allocation or synchronization and doesn't have loops etc. Moreover, after I made this method into a NOP and even removed its invocation completely, the observable program performance didn't change at all (although it got a negligible memory leak, since it was a method for freeing a cheap resource). I'm thinking that this might be because of the constraints that JVM puts on the moments at which a thread's stacktrace may be taken, and it somehow turns out that in my program it is exactly the moments where this method is invoked, although there is absolutely nothing special about it or the context in which it is invoked. What can be the explanation for this phenomenon? What are the aforementioned constraints? What further measurements can I take to clarify the situation?

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  • How to dynamically replace a method implement in ObjC2?

    - by Abhi
    I am trying to learn how to write plugins using SIMBL. I got my plugin to load with the target application, and also know the method that I wish to override. However, I am not able to use class_getInstanceMethod correctly based on snippets on the Internet. Have things changed in OSX 10.6 and/or ObjC2? The following code from culater.net gives "Dereferencing pointer to incomplete type": BOOL DTRenameSelector(Class _class, SEL _oldSelector, SEL _newSelector) { Method method = nil; // First, look for the methods method = class_getInstanceMethod(_class, _oldSelector); if (method == nil) return NO; method->method_name = _newSelector; return YES; } Is there a complete example of how to override a method using SIMBL plugins? Thanks!

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  • NHibernate filters don't work with Session.Get

    - by Khash
    I'm trying to implement a Soft-deletable repository. Usually this can be easily done with a Delete Event listener. To filter out the deleted entities, I can add a Where attribute to my class mapping. However, I also need to implement two more methods in the repository for this entity: Restore and Purge. Restore will "undelete" entities and Purge will hard-delete them. This means I can't use Where attribute (since it block out soft-deleted entities to any access) I tried using filters instead. I can create a filter and enable or disable it within session to achieve the same result. But the problem is filters don't have any effect on Session.Get method (they only affect ICriteria based access). Any ideas as to how solve this problem? Thanks

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  • What is the worst class/variable/function name you have ever encountered

    - by Chris Noe
    Naming things well is arguably Job 1 for professional programmers. Yet we have all suffered from some bad naming choices from time to time. So just to vent a little, what are some doozies that you may have run across? Just to get things started: One of our original developers wasn't sure what to call a secondary key - on what turned out to be a primary table for this app - so he called it: DL2WhateverTheHellThatIs. Unfortunately this system generates entity mappings from the XML, and attributes defined there result in classes, methods, and constants that are referenced through-out the app. To this day it is very hard to find a source file that does not reference this, er, thing! A few actual examples: DL2WhateverTheHellThatIsBean cos = (DL2WhateverTheHellThatIsBean)itr.next(); String code = getDL2WhateverTheHellThatIs().getCode(); From from = new From("DL2WhateverTheHellThatIs"); String filter = "_dL2WhateverTheHellThatIs._code"; (Very difficult to refactor)

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  • How to build a RESTful API?

    - by Sharon Haim Pour
    Hi friends, The issue is this: I have a web application that runs on a PHP server. I'd like to build a REST api for it. I did some research and I figured out that REST api uses HTTP methods (GET, POST...) for certain URI's with an authentication key (not necessarily) and the information is presented back as a HTTP response with the info as XML or JSON (I'd rather JSON). My question is: 1. How do I, as the developer of the app, build those URI's? Do I need to write a PHP code at that URI? 2. How do I build the JSON objects to return as a response? I hope I was clear enough. Thanks!

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  • logging in scala

    - by IttayD
    In Java, the standard idiom for logging is to create a static variable for a logger object and use that in the various methods. In Scala, it looks like the idiom is to create a Logging trait with a logger member and mixin the trait in concrete classes. This means that each time an object is created it calls the logging framework to get a logger and also the object is bigger due to the additional reference. Is there an alternative that allows the ease of use of "with Logging" while still using a per-class logger instance? EDIT: My question is not about how one can write a logging framework in Scala, but rather how to use an existing one (log4j) without incurring an overhead of performance (getting a reference for each instance) or code complexity. Also, yes, I want to use log4j, simply because I'll use 3rd party libraries written in Java that are likely to use log4j.

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  • What are good ways to guarantee business continuity with a SaaS product?

    - by tommyvdz
    For my Bachelor Thesis I am researching how SaaS providers can arrange some sort of business continuity guarantee. You probably know the Source Code Escrow arrangements for 'shrink-wrapped' software. They give customers access to the source code and all applicable documentation whenever the software supplier gets into (financial) trouble. This clearly does not work for SaaS, because customers have no use for just the source code, and customers probably can not afford not being able to login to their CRM system for a couple weeks because the SaaS provider went bankrupt. I am currently researching different methods to solve this problem. Do you know good and practical solutions to solve this continuity problem? Or companies that already offer a good solution? Thanks!

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  • Watin File Download Problem

    - by EmrahIlker
    When I clicked button with mouse, File Download Dialog opens directly. But when Watin Button Click methods click the vert same button on same ie window this message appears and wait my confirm To help protect your security, Internet Explorer blocked this site from downloading files to your computer. Click here for options. I turned off the Information bar for file downloads,(Internet Options-Security-Custom Level-Downloads-Automatic prompting for file downloads--Enable),allow active x content, lower security level for internet etc.. but didn't work. I'm using Win 7, IE8.

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  • Does delegate chaining have to start with a null Delegate?

    - by MCS
    In CLR via C#, Jeffrey Richter gives the following example of delegate chaining (pg. 406): internal delegate void Feedback(Int 32 value); Feedback fb1 = new Feedback(method1); // in the book, these methods Feedback fb2 = new Feedback(method2); // have different names Feedback fb3 = new Feedback(method3); Feedback fbChain = null; fbChain = (Feedback) Delegate.Combine(fbChain, fb1); fbChain = (Feedback) Delegate.Combine(fbChain, fb2); fbChain = (Feedback) Delegate.Combine(fbChain, fb3); Why does the first call to Delegate.Combine have to pass in a null Delegate? Here's how I would have thought it should be written: Feedback fbChain = (Feedback) Delegate.Combine(fb1, fb2); fbChain = (Feedback) Delegate.Combine(fbchain, fb3);

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  • Evaluating Django Chained QuerySets Locally

    - by jnadro52
    Hello All: I am hoping someone can help me out with a quick question I have regarding chaining Django querysets. I am noticing a slow down because I am evaluating many data points in the database to create data trends. I was wondering if there was a way to have the chained filters evaluated locally instead of hitting the database. Here is a (crude) example: pastries = Bakery.objects.filter(productType='pastry') # <--- will obviously always hit DB, when evaluated cannoli = pastries.filter(specificType='cannoli') # <--- can this be evaluated locally instead of hitting the DB when evaluated, as long as pastries was evaluated? I have checked the docs and I do not see anything specifying this, so I guess it's not possible, but I wanted to check with the 'braintrust' first ;-). BTW - I know that I can do this myself by implementing some methods to loop through these datapoints and evaluate the criteria, but there are so many datapoints that my deadline does not permit me manually implementing this. Thanks in advance.

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  • Objects in interface

    - by Peter Kowalchuk
    I created my own object, PKSurvey. In the interface of the View Controller I can define a pointer to it, then in a method I can alloc it and have an instance. How do I keep the instance beyond the method where it was allocated? I assign values in one method and want to be able to use those values in other methods. Should I allocate it in the viewDidLoad method or should I do it somewhere else? @interface DIrectionalDrillerViewController : UIViewController { PKSurvey *Survey=[PKSurvey new]; ---------------- - (void)viewDidLoad { [Survey new];

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  • Organizing a lot of models that use STI in rails

    - by DavidP6
    I have a scenario where I am going to be creating a large number of models that use STI and I'm wondering what the best way to organize this is. I already have other models using STI and I really do not want to add any more files to my models folder. Is there any way to create a folder and add the models using STI there (there could be upwards of 40 b/c each uses its own methods to scrape a different site, but they all save the same data)? This seems like it would be best, or I could add them all to one file but I would rather separate them.

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  • Android EditText and addTextChangedListener

    - by Alex
    im currently porting a database manager to android and due to performance reasons i like to update only propertys that have been modified. Im trying to do this with the addTextChangedListener in order to add modified entrys to a List, but my Program never enters any of its methods. EditText Et = (EditText) Editors.get(Prop.Name); Et.addTextChangedListener(new TextWatcher() { @Override public void afterTextChanged(Editable s) { // TODO Auto-generated method stub } @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { // TODO Auto-generated method stub } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { // TODO Auto-generated method stub if(Prop.GetType() == Property.PROPTYPE.num) { float f = Float.parseFloat(s.toString()); Prop.FromString(f); } else { Prop.FromString(s.toString()); } propertiesToUpdate.add(Prop); }); Et.setText(Prop.ToString());

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  • Scaffold default files are the best practice?

    - by antpaw
    Hey, i have some experience with MVC. but I'm new to rails. I'm using the scaffold command to generate some default files. The model looks clean and nice, but the controller and the views aren't really dry. The contents of new.html.erb and edit.html.erb are almost the same and the methods new/edit and create/update are doing almost the same thing. In other frameworks i've used only one view for updating and creating new entries and also the same method in my controller by setting the id as an optional parameter. Do they use this structure to keep things RESTful (i have not much of a clue about rest :()? Is it the best practice to use this default stuff for crud?

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  • How do I throttle my site's API users?

    - by scotts
    The legitimate users of my site occasionally hammer the server with API requests that cause undesirable results. I want to institute a limit of no more than say one API call every 5 seconds or n calls per minute (haven't figured out the exact limit yet). I could obviously log every API call in a DB and do the calculation on every request to see if they're over the limit, but all this extra overhead on EVERY request would be defeating the purpose. What are other less resource-intensive methods I could use to institute a limit? I'm using PHP/Apache/Linux, for what it's worth.

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  • ActiveX communication

    - by Mario Marinato -br-
    I'm developing an ActiveX EXE that exposes an specific class to a third-party software. This third-party software instanciates an object of this class and uses its methods. Strangely, this third-party software destroys its object of my exposed class as soon as it calls an specific method, but I have no idea why this happens. The only clue I have is that this method is the only one that returns a value. All the other ones are simple 'subs' that do not return any value, and when they are called nothing wrong happens. I'm using VB6. Do you guys have any idea of why it's happening?

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  • javascript: execute a bunch of asynchronous method with one callback

    - by Samuel Michelot
    I need to execute a bunch of asynchronous methods (client SQLite database), and call only one final callback. Of course, the ugly way is: execAll : function(callBack) { asynch1(function() { asynch2(function() { ... asynchN(function() { callBack(); }) }) }); } But I know there are better ways to do it. Intuitively I would detect when all call back has been called with a counter to call the final callback. I think this is a common design-pattern, so if someone could point me in the right direction... Thanks in advance !

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  • How does multiple implementing multiple COM interfaces work in C++?

    - by Martin
    I am trying to understand this example code regarding Browser Helper Objects. Inside, the author implements a single class which exposes multiple interfaces (IObjectWithSite, IDispatch). His QueryInterface function performs the following: if(riid == IID_IUnknown) *ppv = static_cast<BHO*>(this); else if(riid == IID_IObjectWithSite) *ppv = static_cast<IObjectWithSite*>(this); else if (riid == IID_IDispatch) *ppv = static_cast<IDispatch*>(this); I have learned that from a C perspective, interface pointers are just pointers to VTables. So I take it to mean that C++ is capable of returning the VTable of any implemented interface using static_cast. Does this mean that a class constructed in this way has a bunch of VTables in memory (IObjectWithSite, IDispatch, etc)? What does C++ do with the name collisions on the different interfaces (they each have a QueryInterface, AddRef and Release function), can I implement different methods for each of these?

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  • Android: who can help me with setting up this google maps class please??

    - by Capsud
    Hi, Firstly this has turned out to be quite a long post so please bear with me as its not too difficult but you may need to clarify something with me if i haven't explained it correctly. So with some help the other day from guys on this forum, i managed to partially set up my 'mapClass' class, but i'm having trouble with it and its not running correctly so i would like some help if possible. I will post the code below so you can see. What Ive got is a 'Dundrum' class which sets up the listView for an array of items. Then ive got a 'dundrumSelector' class which I use to set up the setOnClickListener() methods on the listItems and link them to their correct views. DundrumSelector class.. public static final int BUTTON1 = R.id.anandaAddressButton; public static final int BUTTON2 = R.id.bramblesCafeAddressButton; public static final int BUTTON3 = R.id.brannigansAddressButton; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); int position = getIntent().getExtras().getInt("position"); if(position == 0){ setContentView(R.layout.ananda); }; if(position == 1){ setContentView(R.layout.bramblescafe); }; if(position == 2){ setContentView(R.layout.brannigans); Button anandabutton = (Button) findViewById(R.id.anandaAddressButton); anandabutton.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { Intent myIntent = new Intent(view.getContext(),MapClass.class); myIntent.putExtra("button", BUTTON1); startActivityForResult(myIntent,0); } }); Button bramblesbutton = (Button) findViewById(R.id.bramblesCafeAddressButton); bramblesbutton.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { Intent myIntent = new Intent(view.getContext(),MapClass.class); myIntent.putExtra("button", BUTTON2); startActivityForResult(myIntent, 0); } }); etc etc.... Then what i did was set up static ints to represent the buttons which you can see at the top of this class, the reason for this is because in my mapClass activity I just want to have one method, because the only thing that is varying is the coordinates to each location. ie. i dont want to have 100+ map classes essentially doing the same thing other than different coordinates into the method. So my map class is as follows... case DundrumSelector.BUTTON1: handleCoordinates("53.288719","-6.241179"); break; case DundrumSelector.BUTTON2: handleCoordinates("53.288719","-6.241179"); break; case DundrumSelector.BUTTON3: handleCoordinates("53.288719","-6.241179"); break; } } private void handleCoordinates(String l, String b){ mapView = (MapView) findViewById(R.id.mapView); LinearLayout zoomLayout = (LinearLayout)findViewById(R.id.zoom); View zoomView = mapView.getZoomControls(); zoomLayout.addView(zoomView, new LinearLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); mapView.displayZoomControls(true); mc = mapView.getController(); String coordinates[] = {l, b}; double lat = Double.parseDouble(coordinates[0]); double lng = Double.parseDouble(coordinates[1]); p = new GeoPoint( (int) (lat*1E6), (int) (lng*1E6)); mc.animateTo(p); mc.setZoom(17); mapView.invalidate(); } Now this is where my problem is. The onClick() events don't even work from the listView to get into the correct views. I have to comment out the methods in 'DundrumSelector' before I can get into their views. And this is what I dont understand, firstly why wont the onClick() events work, because its not even on that next view where the map is. I know this is a very long post and it might be quite confusing so let me know if you want any clarification.. Just to recap, what i'm trying to do is just have one class that sets up the map coordinates, like what i'm trying to do in my 'mapClass'. Please can someone help or suggest another way of doing this! Thanks alot everyone for reading this.

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