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• python fdb save huge data from database to file

  - by peter

  I have this script SELECT = """ select coalesce (p.ID,'') as id, coalesce (p.name,'') as name, from TABLE as p """ self.cur.execute(SELECT) for row in self.cur.itermap(): xml +=" <item>\n" xml +=" <id>" + id + "</id>\n" xml +=" <name>" + name + "</name>\n" xml +=" </item>\n\n" #save xml to file here f = open... and I need to save data from huge database to file. There are 10 000s (up to 40000) of items in my database and it takes very long time when script runs (1 hour and more) until finish. How can I take data I need from database and save it to file "at once"? (as quick as possible? I don't need xml output because I can process data from output on my server later. I just need to do it as quickly as possible. Any idea?) Many thanks!

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• iOS Facebook SDK: FBRequestDelegate only works on AppDelegate??

  - by RMR

  Hi guys, I want to encapsulate all my Facebook interactions within a FacebookFacade class to keep things clean and tidy. I have an instance of the iOS SDK Facebook class within my FacebookFacade. My problem is that when I make a Graph API call within the facade, such as: [self.facebook requestWithGraphPath:@"me" andDelegate:self]; the only method of FBRequestDelegate that gets called is requestLoading: and nothing else. I have tried putting similar code in other places, like in controllers and other models, and there too not all of the FBRequestDelegate methods get called, only requestLoading:. In fact the only way I can get the other FBRequestDelegate methods to be called is to put all my Facebook logic in the AppDelegate and make my AppDelegate the FBRequestDelegate. Why is this the case? Am I missing something here? I definitely do not want to use the AppDelegate as my FBRequestDelegate as I don't want to confuse the purpose of the AppDelegate. Thanks.

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• Python 2.6, 3 abstract base class misunderstanding

  - by Aaron

  I'm not seeing what I expect when I use ABCMeta and abstractmethod. This works fine in python3: from abc import ABCMeta, abstractmethod class Super(metaclass=ABCMeta): @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... And in 2.6: class Super(): __metaclass__ = ABCMeta @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... They both also work fine (I get the expected exception) if I derive Super from object, in addition to ABCMeta. They both "fail" (no exception raised) if I derive Super from list. I want an abstract base class to be a list but abstract, and concrete in sub classes. Am I doing it wrong, or should I not want this in python?

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• Converting a constantly changing scalar value to a changing interval or frequency

  - by eco_bach

  Although I'm coding in Objective C, this is more of a general programming question. What is the best way to convert a constantly changing scalar value to a changing interval or frequency? Right now every time the scalar value changes I am destroying the NSInterval ie [self.myTimer invalidate]; self.myTimer = nil; and creating a new one, but this seems like a VERY expensive way to achieve my goal, since the changing scalar value in my case represents the horizontal velocity of a swipe. For a rough analogy, think of the speed of a swipe being reflected in a visual metronome, the faster you swipe, the higher(shorter interval) the frequency of the metronome.

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• How to override inner class methods if the inner class is defined as a property of the top class

  - by Maddy

  I have a code snippet like this class A(object): class b: def print_hello(self): print "Hello world" b = property(b) And I want to override the inner class b (please dont worry about the lowercase name) behaviour. Say, I want to add a new method or I want to change an existing method, like: class C(A): class b(A.b): def print_hello(self): print "Inner Class: Hello world" b = property(b) Now if I create C's object as c = C(), and call c.b I get TypeError: 'property' object is not callable error. How would I get pass this and call print_hello of the extended inner class? Disclaimer: I dont want to change the code for A class.

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• Sending message from one server to another in Twisted

  - by Casey Patton

  I've implemented my servers in the following way: def makeServer(application, port): factory = protocol.ServerFactory() factory.protocol = MyChat factory.clients = [] internet.TCPServer(port, factory).setServiceParent(application) application = service.Application("chatserver") server1 = makeServer(application, port=1025) server2 = makeServer(application, port=1026) server3 = makeServer(application, port=1027) Note that MyChat is an event handling class that has a "receiveMessage" action: def lineReceived(self, line): print "received", repr(line) for c in self.factory.clients: c.transport.write(message + '\n') I want server1 to be able to pass messages to server2. Rather, I want server1 to be treated as a client of server2. If server1 receives the message "hi" then I want it to send that same exact message to server2. How can I accomplish this?

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• NSAutoreleasePool carrying across methods?

  - by Tim

  I'm building an iPhone application where I detach some threads to do long-running work in the background so as not to hang the UI. I understand that threads need NSAutoreleasePool instances for memory management. What I'm not sure about is if the threaded method calls another method - does that method also need an NSAutoreleasePool? Example code: - (void)primaryMethod { [self performSelectorInBackground:@selector(threadedMethod) withObject:nil]; } - (void)threadedMethod { NSAutoreleasePool *aPool = [[NSAutoreleasePool alloc] init]; // Some code here [self anotherMethod]; // Maybe more code here [aPool drain]; } - (void)anotherMethod { // More code here } The reason I ask is I'm receiving errors that objects are being autoreleased with no pool in place, and are "just leaking." I've seen other questions where people didn't have autorelease pools in place at all, and I understand why an autorelease pool is needed. I'm specifically interested in finding out whether an autorelease pool created in (in this example) threadedMethod applies to objects created in anotherMethod.

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• fluent interface program in Ruby

  - by intern

  we have made the following code and trying to run it. class Numeric def gram self end alias_method :grams, :gram def of(name) ingredient = Ingredient.new(name) ingredient.quantity=self return ingredient end end class Ingredient def initialize(n) @@name= n end def quantity=(o) @@quantity = o return @@quantity end def name return @@name end def quantity return @@quantity end end e= 42.grams.of("Test") a= Ingredient.new("Testjio") puts e.quantity a.quantity=90 puts a.quantity puts e.quantity the problem which we are facing in it is that the output of puts a.quantity puts e.quantity is same even when the objects are different. what we observed is that second object i.e 'a' is replacing the value of the first object i.e. 'e'. the output is coming out to be 42 90 90 but the output required is 42 90 42 can anyone suggest why is it happening? it is not replacing the object as object id's are different..only the values of the objects are replaced.

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• fluent interface program in Ruby

  - by intern

  we have made the following code and trying to run it. class Numeric def gram self end alias_method :grams, :gram def of(name) ingredient = Ingredient.new(name) ingredient.quantity=self return ingredient end end class Ingredient def initialize(n) @@name= n end def quantity=(o) @@quantity = o return @@quantity end def name return @@name end def quantity return @@quantity end end e= 42.grams.of("Test") a= Ingredient.new("Testjio") puts e.quantity a.quantity=90 puts a.quantity puts e.quantity the problem which we are facing in it is that the output of puts a.quantity puts e.quantity is same even when the objects are different. what we observed is that second object i.e 'a' is replacing the value of the first object i.e. 'e'. the output is coming out to be 42 90 90 but the output required is 42 90 42 can anyone suggest why is it happening? it is not replacing the object as object id's are different..only the values of the objects are replaced.

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• iOS 5 - Coredata Sqlite DB losing data after killing app

  - by Brian Boyle

  I'm using coredata with a sqlite DB to persist data in my app. However, each time I kill my app I lose any data that was saved in the DB. I'm pretty sure its because the .sqlite file for my DB is just being replaced by a fresh one each time my app starts, but I can't seem to find any code that will just use the existing one thats there. It would be great if anyone could point me towards some code that could handle this for me. Cheers B - (NSPersistentStoreCoordinator *)persistentStoreCoordinator { if (__persistentStoreCoordinator != nil) { return __persistentStoreCoordinator; } NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"FlickrCoreData.sqlite"]; NSError *error = nil; __persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } return __persistentStoreCoordinator; }

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• Ruby class variable is reset after rails app initialized

  - by Phuong Nguy?n

  I tried to assign a class static variable like this class QueryLogger < Logger @@query_logger_default_instance = nil def self.default_instance # Use global variable because static variable doesn't work @@query_logger_default_instance ||= self.new(STDOUT) end end In initializers folder of my rails app, I added a file with this code block ActiveRecord::Base.logger = QueryLogger.default_instance In a request (action of controller), I make a call to this: QueryLogger.default_instance. My assumption is that the call to default_instance will always report the same. However, it does not. Now I try to watch stuff in NetBeans by setting breakpoint inside default_instance. Thing happen as expected, the default_instance get called twice, one due to the initializer block and one due to the call to my action. Surprising thing is, in both times, @@query_logger_default_instance report nil inside NetBeans inspector. The first nil report is correct, but the second shocked me. It's look like static variable gets reset after rails app initialized. Is there some magic there?

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• Access to nested methods when DSL

  - by Vyacheslav Loginov

  class Warcraft def initialize &block instance_eval &block end def method_missing name, *args, &block instance_variable_set("@#{name}".to_sym, args[0]) self.class.send(:define_method, name, proc { instance_variable_get("@#{name}")}) end def game &block @game = Game.new &block end class Game def initialize &block instance_eval &block end def method_missing name, *args, &block instance_variable_set("@#{name}".to_sym, args[0]) self.class.send(:define_method, name, proc { instance_variable_get("@#{name}")}) end end end warcraft = Warcraft.new do name "Warcraft III" battle_net :iccup game do side :sentinels hero "Furion" rune_appear_every 2 end end puts warcraft.inspect # => #<Warcraft:0x00000000be3e80 @name="Warcraft III", @battle_net=:iccup, @game=#<Warcraft::Game:0x000000009c6c38 @side=:sentinels, @hero="Furion", @rune_appear_every=2>> How to access nested methods? puts warcraft.battle_net # => iccup puts warcraft.side #=> #<Proc:[email protected]:9 (lambda)> puts warcraft.game #=> dsl.rb:18:in `instance_eval': block not supplied (ArgumentError) puts warcraft.game.side #=> dsl.rb:18:in `instance_eval': block not supplied (ArgumentError)

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• Concatenate String to Evernote Markup Language (ENML) in python

  - by Adam the Mediocre

  I am looking to add a string containing the user's text input to the note.content of my note. After reading, I have found how to add resources, but I don't want the resource to be an attachment, I want it to be the actual text. Here is some of the code: title= self.textEditTitle.text() body= self.textEditBody.text() auth_token = "secret stuff!" client = EvernoteClient(token=auth_token, sandbox=True) note_store = client.get_note_store() nBody = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" nBody += "<!DOCTYPE en-note SYSTEM \"http://xml.evernote.com/pub/enml2.dtd\">" nBody += "<en-note>%s</en-note>" % body note = Types.Note() note.title = title note.content= nBody Any advice would be great, as I'm just starting out with this api and it looks like it's full of potential once I figure it out! Here is what I have been mostly reading from: http://dev.evernote.com/documentation/cloud/chapters/ENML.php

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• iPhone: Add background button to view when UITableView has no cells

  - by Nic Hubbard

  I have a UITableViewController, when there is no data to populate the UITableView, I want to add a button, which uses an image. So, rather than the user seeing a tableview with no records, they will see an image that says, "No records have been added, Tap to add one", then they click and we create a new one. I assumed I would just hide the UITableView, then create the button, but I never see the button. Here I am using: if ([[fetchedResultsController sections] count] == 0) { self.tableView.hidden = YES; // Create button w/ image UIButton * btn = [UIButton buttonWithType:UIButtonTypeRoundedRect]; btn.frame = CGRectMake(0, 0, 100, 50); [btn setImage:[UIImage imageNamed:@"no-rides.png"] forState:UIControlStateNormal]; [self.view addSubview:btn]; } Ideas on why I would never see the button? When I show this view, it seems to have a transparent background for a second, then changes white...

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• Returning from method inside a @synchronized block

  - by Michael Waterfall

  I'd just like to know if it's advised to return from a method within a @synchronized block? For example: - (id)test { @synchronized(self) { if (a) return @"A"; else return @"B"; } } As opposed to: - (id)test { NSString *value; @synchronized(self) { if (a) value = @"A"; else value = @"B"; } return value; } This sample is rather simplistic, but sometimes in a complex method it would make things simpler to be able to return from within a @synchronized block.

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• replace values in form.data when form fails validation

  - by John

  Hi I have a form field which requires a json object as its value when it is rendered. When the form is submitted it returns a comma seperated string of ids as its value (not a json string). however if the form does not validate i want to turn this string of ids back into a json string so it will display properly (is uses jquery to render the json object correctly). how would i do this? I was thinking of overwriting the form.clean method but when I tried to change self.data['fieldname'] I got the error 'This QueryDict instance is immutable' and when i tried to change self.cleaned_data['fieldname'] it didn't make a difference to the value of the field. Thanks

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• Aquamacs and IDLWAVE

  - by nicolavianello

  I've just installed the new Aquamacs 2.0 in my Mac Os X 10.6.3 and I'm an happy user of IDLWAVE on Aquamacs for programming in IDL. Unfortunately I run into a problem which I can't understand. I used in my configuration file to put the following (setq idlwave-surround-by-blank t) for the beautiful space around operator. This used to work till Aquamacs 2.0 preview b3 (third beta release) from that on, it stops to work and every time I type an operator (the same for '=' '<' '' etc) I got the following message Debugger entered--Lisp error: (void-variable idlwave-expand-equal) (lambda nil (interactive) (self-insert-command 1) idlwave-expand- equal -1 -1)() call-interactively((lambda nil (interactive) (self-insert-command 1) idlwave-expand-equal -1 -1) nil nil) Any help is welcommed

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• Custom cell and Delete/Move indicators

  - by Kamchatka

  Hello, I have a custom UITableViewCell. However, when I got in edit mode, I don't have any Delete and Move indicators appearing. The custom cell draws itself in the contentView. In layoutSubviews, I make sure there is space on the left and one the right of the contentView so that the controls can appear (if this was the problem). - (void)layoutSubviews { self.contentView.frame = CGRectMake(50, 0, self.frame.size.width - 100, sub.thumbnail.size.height + 20); } In the UITableViewController, I return YES in: - (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath { How could I solve this lack of interactivity. Is there something specific for custom cells? Thanks!

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• drawRect is not refreshing the screen

  - by coure06

  I have this code in my drawRect method float aValue = .0167f; float fValue = 20; for(int i=1; i<=6; i++) { CGContextSelectFont(context, "Arial", fValue, kCGEncodingMacRoman); CGContextSetCharacterSpacing(context, 0); CGContextSetTextDrawingMode(context, kCGTextFill); NSString *hString = [[NSString alloc] initWithFormat:@"%i",i]; CGContextSetRGBFillColor(context, 1, 1, 1, aValue); CGContextShowTextAtPoint(context, i*25, i*16, [hString UTF8String], [hString length]); aValue += 0.167; fValue += 1; } I am calling a method using NSTimer like this staticTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(refreshUIView) userInfo:nil repeats:YES]; here is the refreshUIView -(void)refreshUIView { [self setNeedsDisplay]; } Problem is that drawRect is not clearing the screen, its just over writing what have been written last time on screen.

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• iPhone: Crash in Custom Autorelease Pool

  - by user338322

  My app is crashing when I try to post images in an HTTP request. I am trying to upload images to a server. The crash appears related to my autorelease pool because the crash is trapped at the [pool release] message. Here is the crash report: #0 0x326712f8 in prepareForMethodLookup () #1 0x3266cf5c in lookUpMethod () #2 0x32668f28 in objc_msgSend_uncached () #3 0x33f70996 in NSPopAutoreleasePool () #4 0x33f82a6c in -[NSAutoreleasePool drain] () #5 0x00003d3e in -[CameraViewcontroller save:] (self=0x811400, _cmd=0x319c00d4, number=0x11e210) at /Users/hardikrathore/Desktop/LiveVideoRecording/Classes/CameraViewcontroller.m:266 #6 0x33f36f8a in __NSFireDelayedPerform () #7 0x32da44c2 in CFRunLoopRunSpecific () #8 0x32da3c1e in CFRunLoopRunInMode () #9 0x31bb9374 in GSEventRunModal () #10 0x30bf3c30 in -[UIApplication _run] () #11 0x30bf2230 in UIApplicationMain () #12 0x00002650 in main (argc=1, argv=0x2ffff474) at /Users/hardikrathore/Desktop/LiveVideoRecording/main.m:14 The crash report says that final line of the following code is the point of the crash. (Line No. 266) -(void)save:(id)number { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; j =[number intValue]; while(screens[j] != NULL){ NSLog(@" image made : %d",j); UIImage * image = [UIImage imageWithCGImage:screens[j]]; image=[self imageByCropping:image toRect:CGRectMake(0, 0, 320, 240)]; NSData *imgdata = UIImageJPEGRepresentation(image,0.3); [image release]; CGImageRelease(screens[j]); screens[j] = NULL; UIImage * image1 = [UIImage imageWithCGImage:screens[j+1]]; image1=[self imageByCropping:image1 toRect:CGRectMake(0, 0, 320, 240)]; NSData *imgdata1 = UIImageJPEGRepresentation(image1,0.3); [image1 release]; CGImageRelease(screens[j+1]); screens[j+1] = NULL; NSString *urlString=@"http://www.test.itmate4.com/iPhoneToServerTwice.php"; // setting up the request object now NSMutableURLRequest *request = [[NSMutableURLRequest alloc]init]; [request setURL:[NSURL URLWithString:urlString]]; [request setHTTPMethod:@"POST"]; NSString *fileName=[VideoID stringByAppendingString:@"_"]; fileName=[fileName stringByAppendingString:[NSString stringWithFormat:@"%d",k]]; NSString *fileName2=[VideoID stringByAppendingString:@"_"]; fileName2=[fileName2 stringByAppendingString:[NSString stringWithFormat:@"%d",k+1]]; /* add some header info now we always need a boundary when we post a file also we need to set the content type You might want to generate a random boundary.. this is just the same as my output from wireshark on a valid html post */ NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"]; NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary]; [request addValue:contentType forHTTPHeaderField: @"Content-Type"]; /* now lets create the body of the post */ //NSString *count=[NSString stringWithFormat:@"%d",front];; NSMutableData *body = [NSMutableData data]; [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]]; //[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; count=\"@\"";filename=\"%@.jpg\"\r\n",count,fileName] dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; filename=\"%@.jpg\"\r\n",fileName] dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[NSData dataWithData:imgdata]]; [body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]]; //second boundary NSString *string1 = [[NSString alloc] initWithFormat:@"\r\n--%@\r\n",boundary]; NSString *string2 =[[NSString alloc] initWithFormat:@"Content-Disposition: form-data; name=\"userfile2\"; filename=\"%@.jpg\"\r\n",fileName2]; NSString *string3 =[[NSString alloc] initWithFormat:@"\r\n--%@--\r\n",boundary]; [body appendData:[string1 dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[string2 dataUsingEncoding:NSUTF8StringEncoding]]; //experiment //[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"userfile2\"; filename=\"%@.jpg\"\r\n",fileName2] dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[NSData dataWithData:imgdata1]]; //[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]]; [body appendData:[string3 dataUsingEncoding:NSUTF8StringEncoding]]; // setting the body of the post to the reqeust [request setHTTPBody:body]; // now lets make the connection to the web NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil]; NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding]; if([returnString isEqualToString:@"SUCCESS"]) { NSLog(returnString); k=k+2; j=j+2; [self performSelectorInBackground:@selector(save:) withObject:(id)[NSNumber numberWithInt:j]]; } [imgdata release]; [imgdata1 release]; [NSThread sleepForTimeInterval:.01]; } [pool drain]; //<-------------Line 266 } I don't understand what is causing the crash.

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• Do somthing when animation is ready.

  - by f0rz

  Hi! I have a animation in my navigationbased application. [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.5]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES]; [UIImageView commitAnimations]; Directly after this bit of code i call [self.navigationController popViewControllerAnimated:NO]; The thing is, I dont want to pop my ViewController before my animation is ready. Can someone point me to right directions here ?

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• Django: text fixture fails to load

  - by Esteban Feldman

  Hi all, Did a dumpdata of my project, then in my new test I added it to fixtures. from django.test import TestCase class TestGoal(TestCase): fixtures = ['test_data.json'] def test_goal(self): """ Tests that 1 + 1 always equals 2. """ self.failUnlessEqual(1 + 1, 2) When running the test I get: Problem installing fixture 'XXX/fixtures/test_data.json': DoesNotExist: XXX matching query does not exist. But manually doing loaddata works fine does not when the db is empty. I do a dropdb, createdb a simple syncdb the try loaddata and it fails, same error. Any clue? Python version 2.6.5, Django 1.1.1

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• Setting Back Button Tittle in Navigation Controller problem

  - by Rafael

  Hi, I'm trying to change Back Button tittle in a navigation controller in the following way: In the parent controller I put this in vieDidLoad: self.title = @"Calendars"; self.navigationItem.backBarButtonItem.title = @"Previous"; But this controller is in the stack since I initialized the app: -(void)applicationDidFinishLaunching:(UIApplication *)application{ navController.viewControllers= [NSArray arrayWithObjects:aController,aBcontroller,nil]; [window addSubview:navController.view]; } So, the viewDidLoad in aController is not called until I select the back buttom the first time in the bController... Does anyone knows how to call viewDidLoad just when I push it into the stack? Or do you know another way to change the BackButtom title? Thanks in advanced for your help.

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• NSSortDescriptor for NSFetchRequestController causes crash when value of sorted attribute is changed

  - by AJ

  I have an Core Data Entity with a number of attributes, which include amount(float), categoryTotal(float) and category(string) The initial ViewController uses a FethchedResultsController to retrieve the entities, and sorts them based on the category and then the categoryTotal. No problems so far. NSManagedObjectContext *moc = [self managedObjectContext]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Transaction" inManagedObjectContext:moc]; NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease]; [request setEntity:entityDescription]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(dateStamp >= %@) AND (dateStamp =< %@)", startDate, endDate]; [request setPredicate:predicate]; NSSortDescriptor *sortByCategory = [[NSSortDescriptor alloc] initWithKey:@"category" ascending:sortOrder]; NSSortDescriptor *sortByTotals = [[NSSortDescriptor alloc] initWithKey:@"categoryTotal" ascending:sortOrder]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortByTotals, sortByCategory, nil]; [request setSortDescriptors:sortDescriptors]; NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:managedObjectContext sectionNameKeyPath:@"category" cacheName:nil]; aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; On selecting a row (tableView:didSelectRowAtIndexPath), another view controller is loaded that allows editing of the amount field for the selected entity. Before returning to the first view, categoryTotal is updated by the new ‘amount’. The problem comes when returning to the first view controller, the app bombs with *Serious application error. Exception was caught during Core Data change processing: Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted). with userInfo (null) Program received signal: “EXC_BAD_ACCESS”.* This seems to be courtesy of NSSortDescriptor *sortByTotals = [[NSSortDescriptor alloc] initWithKey:@"categoryTotal" ascending:sortOrder]; If I remove this everything works as expected, but obviously without the sorting I want. I'm guessing this is to do with the sorting order changing due to categoryTotal changing (deletion / insertion) but can't find away fix this. I've verified that values are being modified correctly in the second view, so it appears down to the fetchedResultsController being confused. If the categoryAmount is changed to one that does not change the sort order, then no error is generated I'm not physically changing (ie deleting) the number of items the fetchedResultsController is returning ... the only other issue I can find that seem to generate this error Any ideas would be most welcome Thanks, AJ

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• Primary language - C++/Qt, C#, Java?

  - by Airjoe

  I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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