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  • SQL Alchemy related Objects Error

    - by alex
    from sqlalchemy.orm import relation, backref from sqlalchemy import Table, Column, Integer, String, MetaData, ForeignKey, Date, Sequence from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class GUI_SCENARIO(Base): __tablename__ = 'GUI_SCENARIO' Scenario_ID = Column(Integer, primary_key=True) Definition_Date = Column(Date) guiScenarioDefinition = relation('GUI_SCENARIO_DEFINITION', order_by='GUI_SCENARIO_DEFINITION.Scenario_Definition_ID', backref='guiScenario') def __init__(self, Scenario_ID=None, Definition_Date=None): self.Scenario_ID = Scenario_ID self.Definition_Date = Definition_Date class GUI_SCENARIO_DEFINITION(Base): __tablename__='GUI_SCENARIO_DEFINITION' Scenario_Definition_ID = Column(Integer, Sequence('Scenario_Definition_ID_SEQ'), primary_key=True) Scenario_FK = Column(Integer, ForeignKey('GUI_SCENARIO.Scenario_ID')) Definition_Date=Column(Date) guiScenario = relation(GUI_SCENARIO, backref=backref('guiScenarioDefinition', order_by=Scenario_Definition_ID)) def __init__(self, Scenario_FK, Definition_Date): self.Scenario_FK = Scenario_FK self.Definition_Date = Definition_Date guiScenario = relation(GUI_SCENARIO, backref=backref('guiScenarioDefinition', order_by=Scenario_Definition_ID)) tableNameScenario = "GUI_SCENARIO" scenarioClass = getattr(MappingTablesScenario, tableNameScenario) tableScenario = Table(tableNameScenario, meta, autoload=True) mapper(scenarioClass, tableScenario) scenarioName = scenarioDefinition.name scenarioDefinitionDate = datetime.today() newScenario = MappingTablesScenario.GUI_SCENARIO(scenarioName, scenarioDefinitionDate) print newScenario.guiScenarioDefinition If I try to get the objects related to a scenarioObject, I always get this error: AttributeError: 'GUI_SCENARIO' object has no attribute 'guiScenarioDefinition' Does anyone know, why I get this error?

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  • Core Location question....

    - by Moshe
    This tutorial on mobileorchard.com uses 2 classes (or 2 sets of .h and .m) to implement core location. Can I just use everything there in my existing class? How would I do that? Also, is the - (id) init { self = [super init]; if (self != nil) { self.locationManager = [[[CLLocationManager alloc] init] autorelease]; self.locationManager.delegate = self; // send loc updates to myself } return self; } method the same as the usual initWithNib? I;m trying to quickly implement something based on location information. As much help describing the above linked tutorial would be helpful. Thanks. No - really, Thank You.

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  • Python Vector Class

    - by sfjedi
    I'm coming from a C# background where this stuff is super easy—trying to translate into Python for Maya. There's gotta' be a better way to do this. Basically, I'm looking to create a Vector class that will simply have x, y and z coordinates, but it would be ideal if this class returned a tuple with all 3 coordinates and if you could edit the values of this tuple through x, y and z properties, somehow. This is what I have so far, but there must be a better way to do this than using an exec statement, right? I hate using exec statements. class Vector(object): '''Creates a Maya vector/triple, having x, y and z coordinates as float values''' def __init__(self, x=0, y=0, z=0): self.x, self.y, self.z = x, y, z def attrsetter(attr): def set_float(self, value): setattr(self, attr, float(value)) return set_float for xyz in 'xyz': exec("%s = property(fget=attrgetter('_%s'), fset=attrsetter('_%s'))" % (xyz, xyz, xyz))

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  • Dynamic/runtime method creation (code generation) in Python

    - by Eli Bendersky
    Hello, I need to generate code for a method at runtime. It's important to be able to run arbitrary code and have a docstring. I came up with a solution combining exec and setattr, here's a dummy example: class Viking(object): def __init__(self): code = ''' def dynamo(self, arg): """ dynamo's a dynamic method! """ self.weight += 1 return arg * self.weight ''' self.weight = 50 d = {} exec code.strip() in d setattr(self.__class__, 'dynamo', d['dynamo']) if __name__ == "__main__": v = Viking() print v.dynamo(10) print v.dynamo(10) print v.dynamo.__doc__ Is there a better / safer / more idiomatic way of achieving the same result?

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  • Button color in Navigation bar - iPhone

    - by Mladen
    Hi guys, How to set this yellow button to be gray tinted one. I have tried adding image, but no luck Here is the screenshot: Here is my current code: (id)initWithStyle:(UITableViewStyle)style { if (self = [super initWithStyle:style]) { UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithTitle:NSLocalizedString(@"Settings", @"") style:UIBarButtonItemStyleDone target:self action:@selector(GoToSettings)]; [addButton setImage:[[UIImage imageNamed:@"bg_table.png"] retain]]; self.navigationItem.rightBarButtonItem = addButton; self.navigationItem.hidesBackButton = TRUE; self.view.backgroundColor = [UIColor blackColor]; } return self; }

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  • remove ViewController from memory

    - by user262325
    hello everyone I hope to load an ViewController and do something then unload it from memory. if (self.vViewController5.view.superview==nil) { ViewController5 *blueController = [[ViewController5 alloc] initWithNibName:@"View5" bundle:nil]; self.vViewController5 = blueController; [self.vViewController5 setDelegate:self]; [blueController release]; } [self presentModalViewController:vViewController5 animated:YES]; later, call [self dismissModalViewControllerAnimated:YES]; but I found that dismissModalViewControllerAnimated does not trigger the event viewDidUnload of Viewcontroller5. I try function release but it caused program collapse. I also try removeFromSuperView but it does not trigger the event ViewDidUnload neither. Welcome any comment Thanks interdev

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  • SQL query: Delete a entry which is not present in a join table?

    - by Mestika
    Hi, I’m going to delete all users which has no subscription but I seem to run into problems each time I try to detect the users. My schemas look like this: Users = {userid, name} Subscriptionoffering = {userid, subscriptionname} Now, what I’m going to do is to delete all users in the user table there has a count of zero in the subscriptionoffering table. Or said in other words: All users which userid is not present in the subscriptionoffering table. I’ve tried with different queries but with no result. I’ve tried to say where user.userid <> subscriptionoffering.userid, but that doesn’t seem to work. Do anyone know how to create the correct query? Thanks Mestika

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  • Adding a button inside an image.

    - by iSharreth
    CGRect frame = CGRectMake(round((self.view.bounds.size.width - kImageWidth) / 2.0), kTopPlacement, kImageWidth, kImageHeight); self.containerView = [[[UIView alloc] initWithFrame:frame] autorelease]; [self.view addSubview:self.containerView]; // create the initial image view frame = CGRectMake(0.0, 0.0, kImageWidth, kImageHeight); self.mainView = [[[UIImageView alloc] initWithFrame:frame] autorelease]; self.mainView.image = [UIImage imageNamed:imagePath]; I want to put a button inside mainview.image. How can I do it? Any help will be greatly appreciated.

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  • Testing a Django view cause "AttributeError: 'NoneType' object has no attribute 'handler500'" error

    - by jack
    I just wanted to start testing a Django view using the code below: from django.test.client import Client c = Client() response = c.get('/search/keyword') print response.content It just throws out following error message: "/usr/local/lib/python2.6/dist-packages/django/test/client.py", line 286, in get response = self.request(**r) File "/usr/local/lib/python2.6/dist-packages/django/test/client.py", line 230, in request response = self.handler(environ) File "/usr/local/lib/python2.6/dist-packages/django/test/client.py", line 74, in __call__ response = self.get_response(request) File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 143, in get_response return self.handle_uncaught_exception(request, resolver, exc_info) File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 178, in handle_uncaught_exception callback, param_dict = resolver.resolve500() File "/usr/local/lib/python2.6/dist-packages/django/core/urlresolvers.py", line 268, in resolve500 return self._resolve_special('500') File "/usr/local/lib/python2.6/dist-packages/django/core/urlresolvers.py", line 258, in _resolve_special callback = getattr(self.urlconf_module, 'handler%s' % view_type) AttributeError: 'NoneType' object has no attribute 'handler500' The view works in browser. What's wrong with above code?

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  • Lua and Objective C not running script.

    - by beta
    I am trying to create an objective c interface that encapsulates the functionality of storing and running a lua script (compiled or not.) My code for the script interface is as follows: #import <Cocoa/Cocoa.h> #import "Types.h" #import "lua.h" #include "lualib.h" #include "lauxlib.h" @interface Script : NSObject<NSCoding> { @public s32 size; s8* data; BOOL done; } @property s32 size; @property s8* data; @property BOOL done; - (id) initWithScript: (u8*)data andSize:(s32)size; - (id) initFromFile: (const char*)file; - (void) runWithState: (lua_State*)state; - (void) encodeWithCoder: (NSCoder*)coder; - (id) initWithCoder: (NSCoder*)coder; @end #import "Script.h" @implementation Script @synthesize size; @synthesize data; @synthesize done; - (id) initWithScript: (s8*)d andSize:(s32)s { self = [super init]; self->size = s; self->data = d; return self; } - (id) initFromFile:(const char *)file { FILE* p; p = fopen(file, "rb"); if(p == NULL) return [super init]; fseek(p, 0, SEEK_END); s32 fs = ftell(p); rewind(p); u8* buffer = (u8*)malloc(fs); fread(buffer, 1, fs, p); fclose(p); return [self initWithScript:buffer andSize:size]; } - (void) runWithState: (lua_State*)state { if(luaL_loadbuffer(state, [self data], [self size], "Script") != 0) { NSLog(@"Error loading lua chunk."); return; } lua_pcall(state, 0, LUA_MULTRET, 0); } - (void) encodeWithCoder: (NSCoder*)coder { [coder encodeInt: size forKey: @"Script.size"]; [coder encodeBytes:data length:size forKey:@"Script.data"]; } - (id) initWithCoder: (NSCoder*)coder { self = [super init]; NSUInteger actualSize; size = [coder decodeIntForKey: @"Script.size"]; data = [[coder decodeBytesForKey:@"Script.data" returnedLength:&actualSize] retain]; return self; } @end Here is the main method: #import "Script.h" int main(int argc, char* argv[]) { Script* script = [[Script alloc] initFromFile:"./test.lua"]; lua_State* state = luaL_newstate(); luaL_openlibs(state); luaL_dostring(state, "print(_VERSION)"); [script runWithState:state]; luaL_dostring(state, "print(_VERSION)"); lua_close(state); } And the lua script is just: print("O Hai World!") Loading the file is correct, but I think it messes up at pcall. Any Help is greatly appreciated. Heading

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  • Refining data stored in SQLite - how to join several contacts?

    - by Krab
    Problem background Imagine this problem. You have a water molecule which is in contact with other molecules (if the contact is a hydrogen bond, there can be 4 other molecules around my water). Like in the following picture (A, B, C, D are some other atoms and dots mean the contact). A B . . O / \ H H . . C D I have the information about all the dots and I need to eliminate the water in the center and create records describing contacts of A-C, A-D, A-B, B-C, B-D, and C-D. Database structure Currently, I have the following structure in the database: Table atoms: "id" integer PRIMARY KEY, "amino" char(3) NOT NULL, (HOH for water or other value) other columns identifying the atom Table contacts: "acceptor_id" integer NOT NULL, (the atom near to my hydrogen, here C or D) "donor_id" integer NOT NULL, (here A or B) "directness" char(1) NOT NULL, (this should be D for direct and W for water-mediated) other columns about the contact, such as the distance Current solution (insufficient) Now, I'm going through all the contacts which have donor.amino = "HOH". In this sample case, this would select contacts from C and D. For each of these selected contacts, I look up contacts having the same acceptor_id as is the donor_id in the currently selected contact. From this information, I create the new contact. At the end, I delete all contacts to or from HOH. This way, I am obviously unable to create C-D and A-B contacts (the other 4 are OK). If I try a similar approach - trying to find two contacts having the same donor_id, I end up with duplicate contacts (C-D and D-C). Is there a simple way to retrieve all six contacts without duplicates? I'm dreaming about some one page long SQL query which retrievs just these six wanted rows. :-) It is preferable to conserve information about who is donor where possible, but not strictly necessary. Big thanks to all of you who read this question to this point.

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  • working on lists in python

    - by owca
    I'm trying to make a small modification to django lfs project, that will allow me to deactivate products with no stocks. Unfortunatelly I'm just beginning to learn python, so I have big trouble with its syntax. That's what I'm trying to do. I'm using method 'has_variants' which returns true if product has any. Then I'm building a list from variants for this product. Next for every product in this list (I've called it 'set') I check it's stock and set bool variable 'inactive' to true if product has no stocks and to false if there are any. Finally if 'inactive' is false I'm setting self.active to 0. Code fails in line with: set[] = s How to correct it ? def deactivate(self): """If there are no stocks, deactivate the product. Used in last step of checkout. """ if self.has_variants(): for s in self.variants.filter(active=True): set[] = s for var in set: if var.get_stock_amount() == 0: inactive = True else: inactive = False else: if self.get_stock_amount() == 0: inactive = True if inactive: self.active = False return 0 error log : Traceback (most recent call last): File "manage.py", line 11, in <module> execute_manager(settings) File "/home/purplecow/rails/purpledev/site-packages/django/core/management/__i nit__.py", line 362, in execute_manager utility.execute() File "/home/purplecow/rails/purpledev/site-packages/django/core/management/__i nit__.py", line 303, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/home/purplecow/rails/purpledev/site-packages/django/core/management/bas e.py", line 195, in run_from_argv self.execute(*args, **options.__dict__) File "/home/purplecow/rails/purpledev/site-packages/django/core/management/bas e.py", line 213, in execute translation.activate('en-us') File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/_ _init__.py", line 73, in activate return real_activate(language) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/_ _init__.py", line 43, in delayed_loader return g['real_%s' % caller](*args, **kwargs) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/t rans_real.py", line 205, in activate _active[currentThread()] = translation(language) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/t rans_real.py", line 194, in translation default_translation = _fetch(settings.LANGUAGE_CODE) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/t rans_real.py", line 180, in _fetch app = import_module(appname) File "/home/purplecow/rails/purpledev/site-packages/django/utils/importlib.py" , line 35, in import_module __import__(name) File "/home/purplecow/rails/purpledev/lfs/caching/__init__.py", line 1, in <mo dule> from listeners import * File "/home/purplecow/rails/purpledev/lfs/caching/listeners.py", line 10, in < module> from lfs.cart.models import Cart File "/home/purplecow/rails/purpledev/lfs/cart/models.py", line 8, in <module> from lfs.catalog.models import Product File "/home/purplecow/rails/purpledev/lfs/catalog/__init__.py", line 1, in <mo dule> from listeners import * File "/home/purplecow/rails/purpledev/lfs/catalog/listeners.py", line 5, in <m odule> from lfs.catalog.models import PropertyGroup File "/home/purplecow/rails/purpledev/lfs/catalog/models.py", line 589 set[] = s ^ SyntaxError: invalid syntax

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  • initWithCoder works, but init seems to be overwriting my objects properties?

    - by Zigrivers
    Hi guys, I've been trying to teach myself how to use the Archiving/Unarchiving methods of NSCoder, but I'm stumped. I have a Singleton class that I have defined with 8 NSInteger properties. I am trying to save this object to disk and then load from disk as needed. I've got the save part down and I have the load part down as well (according to NSLogs), but after my "initWithCoder:" method loads the object's properties appropriately, the "init" method runs and resets my object's properties back to zero. I'm probably missing something basic here, but would appreciate any help! My class methods for the Singleton class: + (Actor *)shareActorState { static Actor *actorState; @synchronized(self) { if (!actorState) { actorState = [[Actor alloc] init]; } } return actorState; } -(id)init { if (self = [super init]) { NSLog(@"New Init for Actor started...\nStrength: %d", self.strength); } return self; } -(id)initWithCoder:(NSCoder *)coder { if (self = [super init]) { strength = [coder decodeIntegerForKey:@"strength"]; dexterity = [coder decodeIntegerForKey:@"dexterity"]; stamina = [coder decodeIntegerForKey:@"stamina"]; will = [coder decodeIntegerForKey:@"will"]; intelligence = [coder decodeIntegerForKey:@"intelligence"]; agility = [coder decodeIntegerForKey:@"agility"]; aura = [coder decodeIntegerForKey:@"aura"]; eyesight = [coder decodeIntegerForKey:@"eyesight"]; NSLog(@"InitWithCoder executed....\nStrength: %d\nDexterity: %d", self.strength, self.dexterity); [self retain]; } return self; } -(void) encodeWithCoder:(NSCoder *)encoder { [encoder encodeInteger:strength forKey:@"strength"]; [encoder encodeInteger:dexterity forKey:@"dexterity"]; [encoder encodeInteger:stamina forKey:@"stamina"]; [encoder encodeInteger:will forKey:@"will"]; [encoder encodeInteger:intelligence forKey:@"intelligence"]; [encoder encodeInteger:agility forKey:@"agility"]; [encoder encodeInteger:aura forKey:@"aura"]; [encoder encodeInteger:eyesight forKey:@"eyesight"]; NSLog(@"encodeWithCoder executed...."); } -(void)dealloc { //My dealloc stuff goes here [super dealloc]; } I'm a noob when it comes to this stuff and have been trying to teach myself for the last month, so forgive anything obvious. Thanks for the help!

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  • Help need to with MySQL query to join data spanning multiple tables and use data as column names

    - by gurun8
    I need a little help putting together a SQL query that will give me the following resultsets: and The data model looks like this: The tricky part for me is that the columns to the right of the "Product" in the resultset aren't really columns in the database but rather key/value pairs spanned across the data model. Table data is as follows: My apologies in advance for the image heavy question and the image quality. This just seemed like the easiest way to convey the information. It'll probably take someone less time to write the query statement to achieve the results than it did for me to assemble this question. By the way, the "product_option" table image is truncated but it illustrated the general idea of the data structure. The MySQL server version is 5.1.45.

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  • XNA 4.0 - What happens when the window is minimized?

    - by Conrad Clark
    Hello. I'm learning F#, and decided to try making simple XNA games for windows using F# (pure enthusiasm) , and got a window with some images showing up. Here's the code: (*Methods*) member self.DrawSprites() = _spriteBatch.Begin() for i = 0 to _list.Length-1 do let spentity = _list.List.ElementAt(i) _spriteBatch.Draw(spentity.ImageTexture,new Rectangle(100,100,(int)spentity.Width,(int)spentity.Height),Color.White) _spriteBatch.End() (*Overriding*) override self.Initialize() = ChangeGraphicsProfile() _graphicsDevice <- _graphics.GraphicsDevice _list.AddSprite(0,"NagatoYuki",992.0,990.0) base.Initialize() override self.LoadContent() = _spriteBatch <- new SpriteBatch(_graphicsDevice) base.LoadContent() override self.Draw(gameTime : GameTime) = base.Draw(gameTime) _graphics.GraphicsDevice.Clear(Color.CornflowerBlue) self.DrawSprites() And the AddSprite Method: member self.AddSprite(ID : int,imageTexture : string , width : float, height : float) = let texture = content.Load<Texture2D>(imageTexture) list <- list @ [new SpriteEntity(ID,list.Length, texture,Vector2.Zero,width,height)] The _list object has a ContentManager, here's the constructor: type SpriteList(_content : ContentManager byref) = let mutable content = _content let mutable list = [] But I can't minimize the window, since when it regains its focus, i get this error: ObjectDisposedException Cannot access a disposed object. Object name: 'GraphicsDevice'. What is happening?

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  • django: _init_ def work but does not update to class in django form

    - by tgngo
    Hi expert there, this is my form: class IPTrackerSearchForm(forms.Form): keyword = forms.CharField(max_length=100, widget=forms.TextInput(attrs={'size':'50'})) search_in = forms.ChoiceField(required=False, choices=ANY_CHOICE + MODULE_SEARCH_IN_CHOICES) product = forms.CharField(max_length=64,widget=forms.TextInput(attrs={'size':'50'})) family = forms.CharField(max_length=64,widget=forms.TextInput(attrs={'size':'50'})) temp_result = Merlin.objects.values('build').distinct() result = [(value['build'], value['build']) for value in temp_result] build = forms.ChoiceField(choices=ANY_CHOICE + result) circuit_name = forms.CharField(max_length=256,widget=forms.TextInput(attrs={'size':'50'})) parameterization = forms.CharField(max_length=1024,widget=forms.TextInput(attrs={'size':'50'})) metric = forms.CharField(max_length=64,widget=forms.TextInput(attrs={'size':'50'})) show_in_one_page = forms.BooleanField(required=False, label="Show filtered result in one page", widget=forms.CheckboxInput(attrs={'class':'checkbox'})) def __init__(self, *args, **kwargs): super(IPTrackerSearchForm, self).__init__(*args, **kwargs) temp_result = Merlin.objects.values('build').distinct() self.result = [(value['build'], value['build']) for value in temp_result] self.build = forms.ChoiceField(choices=ANY_CHOICE + self.result) print self.result With the purpose that, each time I refresh the webpage, when have new record to "build" column in database. It should update to the drop down box "build" here but It never update unless restart the server. I use print and see that ini detect new recrd but can notrefect to build in Class. Many thanks

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  • SQLAlchemy - how to map against a read-only (or calculated) property

    - by Jeff Peck
    I'm trying to figure out how to map against a simple read-only property and have that property fire when I save to the database. A contrived example should make this more clear. First, a simple table: meta = MetaData() foo_table = Table('foo', meta, Column('id', String(3), primary_key=True), Column('description', String(64), nullable=False), Column('calculated_value', Integer, nullable=False), ) What I want to do is set up a class with a read-only property that will insert into the calculated_value column for me when I call session.commit()... import datetime def Foo(object): def __init__(self, id, description): self.id = id self.description = description @property def calculated_value(self): self._calculated_value = datetime.datetime.now().second + 10 return self._calculated_value According to the sqlalchemy docs, I think I am supposed to map this like so: mapper(Foo, foo_table, properties = { 'calculated_value' : synonym('_calculated_value', map_column=True) }) The problem with this is that _calculated_value is None until you access the calculated_value property. It appears that SQLAlchemy is not calling the property on insertion into the database, so I'm getting a None value instead. What is the correct way to map this so that the result of the "calculated_value" property is inserted into the foo table's "calculated_value" column?

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  • Help needed with MySQL query to join data spanning multiple tables with data used as column names

    - by gurun8
    I need a little help putting together a SQL query that will give me the following resultsets: and The data model looks like this: The tricky part for me is that the columns to the right of the "Product" in the resultset aren't really columns in the database but rather key/value pairs spanned across the data model. Table data is as follows: My apologies in advance for the image heavy question and the image quality. This just seemed like the easiest way to convey the information. It'll probably take someone less time to write the query statement to achieve the results than it did for me to assemble this question. By the way, the "product_option" table image is truncated but it illustrated the general idea of the data structure. The MySQL server version is 5.1.45.

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  • Objective-C convention to prevent "local declaration hides instance variable" warning

    - by Nippysaurus
    Is there a common convention for dealing with these scenarios? The following code is what I am using .. -(id) initWithVariableName: (NSString*)variableName withComparisonValue:(NSString*)comparisonValue { self.mustExist = NO; self.reverseCondition = NO; self.regularExpression = NO; self.variableName = variableName; self.comparisonValue = comparisonValue; return self; } But I am getting "Local declaration of 'variableName' hides instance variable" and the same for "comparisonValue". The function signature seems logical to me, but surely there must be a more "acceptable" standard which will still make sense and be accurate but not generate annoying warnings?

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  • Django database caching

    - by hekevintran
    I have a Django form that uses an integer field to lookup a model object by its primary key. The form has a save() method that uses the model object referred to by the integer field. The model's manager's get() method is called twice, once in the clean method and once in the save() method: class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is the first call to get MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): id_a = self.cleaned_data['id_a'] # here is the second call to get my_model_object = MyModel.objects.get(id=id_a) # do other stuff I wasn't sure whether this hits the database two times or one time so I returned the object itself in the clean method so that I could avoid a second get() call. Does calling get() hit the database two times? Or is the object cached in the thread? class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is my workaround return MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): # looking up the cleaned value returns the model object my_model_object = self.cleaned_data['id_a'] # do other stuff

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  • How do I join three tables with SQLalchemy and keeping all of the columns in one of the tables?

    - by jimka
    So, I have three tables: The class defenitions: engine = create_engine('sqlite://test.db', echo=False) SQLSession = sessionmaker(bind=engine) Base = declarative_base() class Channel(Base): __tablename__ = 'channel' id = Column(Integer, primary_key = True) title = Column(String) description = Column(String) link = Column(String) pubDate = Column(DateTime) class User(Base): __tablename__ = 'user' id = Column(Integer, primary_key = True) username = Column(String) password = Column(String) sessionId = Column(String) class Subscription(Base): __tablename__ = 'subscription' userId = Column(Integer, ForeignKey('user.id'), primary_key=True) channelId = Column(Integer, ForeignKey('channel.id'), primary_key=True) And the SQL commands that are executed to create them: CREATE TABLE subscription ( "userId" INTEGER NOT NULL, "channelId" INTEGER NOT NULL, PRIMARY KEY ("userId", "channelId"), FOREIGN KEY("userId") REFERENCES user (id), FOREIGN KEY("channelId") REFERENCES channel (id) ); CREATE TABLE user ( id INTEGER NOT NULL, username VARCHAR, password VARCHAR, "sessionId" VARCHAR, PRIMARY KEY (id) ); CREATE TABLE channel ( id INTEGER NOT NULL, title VARCHAR, description VARCHAR, link VARCHAR, "pubDate" TIMESTAMP, PRIMARY KEY (id) ); NOTE: I know user.username should be unique, need to fix that, and I'm not sure why SQLalchemy creates some row names with the double-quotes. And I'm trying to come up with a way to retrieve all of the channels, as well as an indication on what channels one particular user (identified by user.sessionId together with user.id) has a subscription on. For example, say we have four channels: channel1, channel2, channel3, channel4; a user: user1; who has a subscription on channel1 and channel4. The query for user1 would return something like: channel.id | channel.title | subscribed --------------------------------------- 1 channel1 True 2 channel2 False 3 channel3 False 4 channel4 True This is a best-case result, but since I have absolutely no clue as how to accomplish the subscribed column, I've been instead trying to get the particular users id in the rows where the user has a subscription and where a subscription is missing, just leave it blank. The database engine that I'm using together with SQLalchemy atm. is sqlite3 I've been scratching my head over this for two days now, I've no problem joining together all three by way of the subscription table but then all of the channels where the user does not have a subscription gets omitted. I hope I've managed to describe my problem sufficiently, thanks in advance.

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  • How to do a Postgresql subquery in select clause with join in from clause like SQL Server?

    - by Ricardo
    I am trying to write the following query on postgresql: select name, author_id, count(1), (select count(1) from names as n2 where n2.id = n1.id and t2.author_id = t1.author_id ) from names as n1 group by name, author_id This would certainly work on Microsft SQL Server but it does not at all on postegresql. I read its documentation a bit and it seems I could rewrite it as: select name, author_id, count(1), total from names as n1, (select count(1) as total from names as n2 where n2.id = n1.id and n2.author_id = t1.author_id ) as total group by name, author_id But that returns the following error on postegresql: "subquery in FROM cannot refer to other relations of same query level". So I'm stuck. Does anyone know how I can achieve that? Thanks

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  • Core Data deleteObject: sets attributes to nil

    - by SG1
    I am implementing an undo/redo mechanism in my app. This works fine for lots of cases. However, I can't undo past deleteObject:. the object is correctly saved in the undo queue, and I get it back and reinsterted into the Core Data stack just fine when calling undo. The problem is that all it's attributes are getting set to nil when I delete it. I have an entity "Canvas" with a to-many relationship called "graphics" to a "Graphic" entity, which has its inverse set to "canvas". Deleting a Graphic, then inserting it back, doesn't work. Here's the code (the redo method is basically the same): - (void)deleteGraphic:(id)aGraphic { //NSLog(@"undo drawing"); //Prepare the undo/redo [self.undoManager beginUndoGrouping]; [self.undoManager setActionName:@"Delete Graphic"]; [[self.detailItem valueForKey:@"graphics"] removeObject:aGraphic]; [[self managedObjectContext] deleteObject:aGraphic]; //End undo/redo [self.undoManager registerUndoWithTarget:self selector:@selector(insertGraphic:) object:aGraphic]; [self.undoManager endUndoGrouping]; NSLog(@"graphics are %@", [self sortedGraphics]); //Update drawing [self.quartzView setNeedsDisplay]; } and here's the wierdness: Before delete: graphics are ( <NSManagedObject: 0x1cc3f0> (entity: Graphic; id: 0x1c05f0 <x-coredata:///Graphic/t840FE8AD-F2E7-4214-822F-7994FF93D4754> ; data: { canvas = 0x162b70 <x-coredata://A919979E-75AD-474D-9561-E0E8F3388718/Canvas/p20>; content = <62706c69 73743030 d4010203 04050609 0a582476 65727369 6f6e5424 746f7059 24617263 68697665 7258246f 626a6563 7473>; frameRect = nil; label = nil; order = 1; path = "(...not nil..)"; traits = "(...not nil..)"; type = Path; }) After redo: graphics are ( <NSManagedObject: 0x1cc3f0> (entity: Graphic; id: 0x1c05f0 <x-coredata:///Graphic/t840FE8AD-F2E7-4214-822F-7994FF93D4754> ; data: { canvas = nil; content = nil; frameRect = nil; label = nil; order = 0; path = nil; traits = nil; type = nil; }), You can see it's the same object, just totally bleached by Core Data. The relationship delete rouls apparently have nothing to do with it as I've set them to "No Action" in a test.

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  • Django: Determining if a user has voted or not

    - by TheLizardKing
    I have a long list of links that I spit out using the below code, total votes, submitted by, the usual stuff but I am not 100% on how to determine if the currently logged in user has voted on a link or not. I know how to do this from within my view but do I need to alter my below view code or can I make use of the way templates work to determine it? I have read http://stackoverflow.com/questions/1528583/django-vote-up-down-method but I don't quite understand what's going on ( and don't need any ofjavascriptery). Models (snippet): class Link(models.Model): category = models.ForeignKey(Category, blank=False, default=1) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add=True) modified = models.DateTimeField(auto_now=True) url = models.URLField(max_length=1024, unique=True, verify_exists=True) name = models.CharField(max_length=512) def __unicode__(self): return u'%s (%s)' % (self.name, self.url) class Vote(models.Model): link = models.ForeignKey(Link) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add=True) def __unicode__(self): return u'%s vote for %s' % (self.user, self.link) Views (snippet): links = Link.objects.select_related().annotate(votes=Count('vote')).order_by('-created')

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