I am new to Django and Python, building my first app using TDD... I wanted to copy an instance of Task, a model object. I used the following code, which works correctly during the tests:
import copy
class Task(models.Model):
...
def make_copy(self):
new_task = copy.copy(self)
new_task.save()
return new_task
But when running this code 'normally', in the server, I noticed it was not working: no new object was created. I found out I had to add new_task.id = None just before saving, and I understand the reason for this...
But if copy.copy does not know about Django and thus will not change the id itself, why is it the case that the object returned has id == None during the tests?
It sounds like your test case is not fully matching the usage in your "normal" use case.
The id field is set for objects that exist in the database. If you pass your make_copy() method an object with id set, it will appear to fail because it's not making a new database object, it's just saving an existing object (through the Python copy, with an existing id).
I'd guess your test case is passing Task objects to make_copy() with id of None (and therefore appearing to work), while in "normal" usage, the objects are coming in with id set. (You could test this hypothesis with a simple print or assert statement).
One simple solution might be to set id to None right after your copy operation. That way, a new database object is always created.
Finally, someone else with the same situation: http://www.nerdydork.com/copy-model-object-in-django.html
Related
I'm using DjangoModelFactory to create custom objects needed for tests. The issue is that I would like to write test for situation where there is a request for nonexistent object. Is there any elegant way to automatically generate such ID. One idea I have had was to use really big number, as test suite should never reach such number. Another idea is to create object, store ID and then delete the object. Both those solutions are somewhat hacky - firs has rather risky assumption that the big number will not be assigned as ID as part of tests, the other is based on additional logic which makes tests more dependent on non-related logic. Is there any simple and out-of-the box solution to get id which is not assigned to any object?
I am working on some Django/Python code.
Basically, the backend of my code gets sent a dict of parameters named 'p'. These values all come off Django models.
When I tried to override them as such:
p['age']=25
I got a 'model error'. Yet, if I write:
p.age=25
it works fine.
My suspicion is that, internally, choice #1 tries to set a new value to an instance of a class created by Django that objects to being overridden, but internally Python3 simply replaces the Django instance with a "new" attribute of the same name ('age'), without regard for the prior origin, type, or class of what Django created.
All of this is in a RESTful framework, and actually in test code. So even if I am right I don't believe it changes anything for me in reality.
But can anyone explain why one type of assignment to an existing dict works, and the other fails?
p is a class, not a dict. Django built it that way.
But, as such, one approach (p.age) lets you change an attribute of the object in the class.
I'm trying to create a callable object to return the default value to use for a field when creating a new instance.
The logic for the value is dependent on other data in the model. I tried creating a separate class but have not hit on the right combination of factors. Example:
in models.py:
Class Box(models.Model):
inv_id = models.CharField(max_length=16,default=gen_inv_id())
The callable object will need to query the database model and increment a table value. I tried creating a class in a separate .py module under the app, but it needs a method to return a value. OO is not my strong suit at this point. I think the model has become invalid and the method depends on it so it seems like a chicken/egg scenario has emerged.
Thanks for any help.
Since forever (pre 1.0 days) the default keyword supported callables. The issue with your code is you're not passing in a callable (default=gen_inv_id), but the result of a callable (default=gen_inv_id()).
So you probably want to do:
Class Box(models.Model):
inv_id = models.CharField(max_length=16,default=gen_inv_id)
Check out the docs for the latest version that describes this:
https://docs.djangoproject.com/en/1.4/ref/models/fields/#default
I've run into this before. One thing you can do is to overwrite the class's save method, so that you first save the parameters you need to do the computation, then do the computation and resave. If you're overwriting the save method you'll need to call super.save() (I forget what the exact notation is)
edit: the notation for super.save is super(Model, self).save(*args, **kwargs)
I'm new to symfony2 and doctrine.
here is the problem as I see it.
i cannot use :
$repository = $this->getDoctrine()->getRepository('entity');
$my_object = $repository->findOneBy($index);
on an object that is persisted, BUT NOT FLUSHED YET !!
i think getRepository read from DB, so it will not find a not-flushed object.
my question: how to read those objects that are persisted (i think they are somewhere in a "doctrine session") to re-use them before i do flush my entire batch ?
every profile has 256 physical plumes.
every profile has 1 plumeOptions record assigned to it.
In plumeOptions, I have a cartridgeplume which is a FK for PhysicalPlume.
every plume is identified by ID (auto-generated) and an INDEX (user-generated).
rule: I say profile 1 has physical_plume_index number 3 (=index) connected to it.
now, I want to copy a profile with all its related data to another profile.
new profile is created. New 256 plumes are created and copied from older profile.
i want to link the new profile to the new plume index 3.
check here: http://pastebin.com/WFa8vkt1
I think you might want to have a look at this function:
$entityManager->getUnitOfWork()->getScheduledEntityInsertions()
Gives you back a list of entity objects which are persisting yet.
Hmm, I didn't really read your question well, with the above you will retrieve a full list (as an array) but you cannot query it like with getRepository. I will try found something for u..
I think you might look at the problem from the wrong angle. Doctrine is your persistance layer and database access layer. It is the responsibility of your domain model to provide access to objects once they are in memory. So the problem boils down to how do you get a reference to an object without the persistance layer?
Where do you create the object you need to get hold of later? Can the method/service that create the object return a reference to the controller so it can propagate it to the other place you need it? Can you dispatch an event that you listen to elsewhere in your application to get hold of the object?
In my opinion, Doctrine should be used at the startup of the application (as early as possible), to initialize the domain model, and at the shutdown of the application, to persist any changes to the domain model during the request. To use a repository to get hold of objects in the middle of a request is, in my opinion, probably a code smell and you should look at how the application flow can be refactored to remove that need.
Your is a business logic problem effectively.
Querying down the Database a findby Query on Object that are not flushed yet, means heaving much more the DB layer querying object that you have already in your function scope.
Also Keep in mind a findOneBy will retrieve also other object previously saved with same features.
If you need to find only among those new created objects, you should make f.e. them in a Session Array Variable, and iterate them with the foreach.
If you need a mix of already saved items + some new items, you should threate the 2 parts separately, one with a foreach , other one with the repository query!
I've created a small django project with three applications, and I'm now writing tests for one of them. I needed to pass some information between differente views and differents templates,but that information should not be visible to the user. My first attempt was to pass this informatio as hidden fields in a HTML form, but then it was pointed to me that that did not make it completely invisible. So, I stored this information in the request.session dictionary and it went all right.
That said, my problem arised while testing. According to the django documentation (http://docs.djangoproject.com/en/1.2/topics/testing/) when you have to modify the session dictionary during testing you should first store it in a variable, modify it, and then save the variable.
So my testing code is something like this:
class Test_Atacar(TestCase):
fixtures = ["testBase.json"]
def test_attack_without_troops(self):
red_player = Player.objects.get(color=RED)
self.failUnless(red_player != None)
session = self.client.session
session["player_id"] = red_player.id
session.save()
response = self.client.get("/espectador/sadfxc/", follow=True)
But when I run the python manage.py test, I get an AttributeError, saying that dict, has no attribute save().
I read somewhere else (http://code.djangoproject.com/ticket/11475) that I should try doing a self.client.get to any other URL BEFORE manipulating the session so that it would become a "real" session, but I kept getting the same AttributeError.
when you have to modify the session dictionary during testing you should first store it in a variable, modify it, and then save the variable
This line means that if you want to make some changes into some of the session variables, do not make them directly into session. Store the data in the variable, make changes in that variable and then put that variable into session dictionary. session is like any other dictionary.
#anand I know it's weird but it indeeds work. What I had to do to make it work, besides not manipulating directly the variable was to make a self.client.get("/dummy/") where dummy is an URL that uses a dummy view. This view only modifies the attribute of the request it gets as argument. Honestly, I don't know what goes on behind the scenes that makes this work