given the following situation:
models.py
from .managers import PersonManager
from django.db import models
class Person(models.Model):
first_name = models.CharField(max_length=256)
last_name = models.CharField(max_length=256)
managers.py
from .models import Person
from django.db import managers
class PersonManager(models.Manager):
def create(self, person_dict):
new_person = Person(
first_name=person_dict['first_name']
last_name=person_dict['last_name'])
new_person.save()
How can I write my model manager to avoid circular import?
It is actually not working, my guess is that I would have to create my object inside my manager without refering to it as class Person, instead I should use a more general generic Django name. Any thoughts?
There are a few options here.
Firstly, you could define the model and the manager in the same file; Python has no requirement or expectation that each class is in its own file.
Secondly, you don't actually need to import the model into the manager. Managers belong to models, not the other way round; from within the manager, you can refer to the model class via self.model.
And finally, if that's all your manager is doing, there is no reason for it at all. Managers already have a create method; it takes keyword parameters, rather than a dict, but that just means you can call it with Person.objects.create(**person_dict).
Related
I have a simple model User that simply extends the AbstractUser class with some extra fields. I tried adding "objects = UserQuerySet.as_manager() but is giving me an error "get_by_natural_key() is not defined" when i try to create a superuser. It seems that it is overwriting the regular user manager so i am losing the methods that it comes with. I tried renaming the objects field to something else so I wouldnt be overwriting the default one but it still the same error. Is there any way to simply add querysets without creating whole new manager class, extending the BaseUserManager, adding all of the default methods from scratch, and adding my custom queryset to it? I just want to keep the regular UserManager and just add querysets.
class UserQuerySet(QuerySet):
def more_ten(self):
return self.filter(points__gt=10)
class User(AbstractUser):
points = IntegerField(default=0)
tester = UserQuerySet.as_manager()
#objects = UserQuerySet.as_manager()
According to the docs, your custom user manager should inherit from BaseUserManager
class UserQuerySet(QuerySet):
def more_ten(self):
return self.filter(points__gt=10)
from django.contrib.auth.models import UserManager as OldUserManager
class UserManager(OldUserManager):
def get_queryset(self):
return UserQuerySet(model=self.model, using=self._db, hints=self._hints)
class User(AbstractUser):
objects = UserManager()
I know, this question has been already asked many times in SO, but most of the answers I read were either outdated (advising the now deprecated AUTH__PROFILE_MODULE method), or were lacking of a concrete example.
So, I read the Django documentation [1,2], but I lack a real example on how to use it properly.
In fact, my problem comes when a new user is created (or updated) through a form. The user is obviously created but, the fields from the extension are all unset. I know that the Django documentation is stating that:
These profile models are not special in any way - they are just Django models that happen to have a one-to-one link with a User model. As such, they do not get auto created when a user is created, but a django.db.models.signals.post_save could be used to create or update related models as appropriate.
But, I don't know how to do it in practice (should I add a a receiver and if 'yes', which one).
For now, I have the following (taken from the documentation for the sake of brevity):
File models.py
from django.contrib.auth.models import User
class Employee(models.Model):
user = models.OneToOneField(User)
department = models.CharField(max_length=100)
File admin.py
from django.contrib import admin
from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.models import User
from my_user_profile_app.models import Employee
# Define an inline admin descriptor for Employee model
class EmployeeInline(admin.StackedInline):
model = Employee
can_delete = False
verbose_name_plural = 'employee'
# Define a new User admin
class UserAdmin(UserAdmin):
inlines = (EmployeeInline, )
# Re-register UserAdmin
admin.site.unregister(User)
admin.site.register(User, UserAdmin)
File forms.py
class SignupForm(account.forms.SignupForm):
department = forms.CharField(label="Department", max_length=100)
class SettingsForm(account.forms.SignupForm):
department = forms.CharField(label="Department", max_length=100)
Then, in my code, I use it like this:
u = User.objects.get(username='fsmith')
freds_department = u.employee.department
But, Signup and Settings forms do not operates as expected and new values for the departement is not recorded.
Any hint is welcome !
I have looked at all the answers but none does really hold the solution for my problem (though some of you gave me quite good hints for looking in the right direction). I will summarize here the solution I have found to solve my problem.
First of all, I have to admit I didn't tell everything about my problem. I wanted to insert extra fields in the User model and use other apps such as the default authentication scheme of Django. So, extending the default User by inheritance and setting AUTH_USER_MODEL was a problem because the other Django applications were stopping to work properly (I believe they didn't use user = models.OneToOneField(settings.AUTH_USER_MODEL) but user = models.OneToOneField(User)).
As, it would have been too long to rewrite properly the other applications I am using, I decided to add this extra field through a One-to-One field. But, the documentation miss several points that I would like to fill in the following.
So, here is a complete example of adding an extra field to the User model with other applications using the same model.
First, write the description of the model gathering the extra fields that you want to add to your models.py file:
from django.contrib.auth.models import User
class UserProfile(models.Model):
user = models.OneToOneField(User)
extra_field = models.CharField(max_length=100)
Then, we need to trigger the addition of an object UserProfile each time a User is created. This is done through attaching this code to the proper signal in the receiver.py file:
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver
from my_user_profile_app.models import UserProfile
#receiver(post_save, sender=User)
def handle_user_save(sender, instance, created, **kwargs):
if created:
UserProfile.objects.create(user=instance)
Now, if you want to be able to modify it through the administration interface, just stack it with the usual UserAdmin form in the admin.py file.
from django.contrib import admin
from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.models import User
from my_user_profile_app.models import UserProfile
# Define an inline admin descriptor for UserProfile model
class UserProfileInline(admin.StackedInline):
model = UserProfile
can_delete = False
# Define a new User admin
class UserAdmin(UserAdmin):
inlines = (UserProfileInline, )
# Re-register UserAdmin
admin.site.unregister(User)
admin.site.register(User, UserAdmin)
Then, it is time now to try to mix this extra field with the default Django authentication application. For this, we need to add an extra field to fill in the SignupForm and the SettingsForm through inheritance in the forms.py file:
import account.forms
from django import forms
class SignupForm(account.forms.SignupForm):
extra_field = forms.CharField(label="Extra Field", max_length=100)
class SettingsForm(account.forms.SignupForm):
extra_field = forms.CharField(label="Extra Field", max_length=100)
And, we also need to add some code to display and get properly the data that you have been added to the original User model. This is done through inheritance onto the SignupView and the SettingsView views in the views.py file:
import account.views
from my_user_profile_app.forms import Settings, SignupForm
from my_user_profile_app.models import UserProfile
class SettingsView(account.views.SettingsView):
form_class = SettingsForm
def get_initial(self):
initial = super(SettingsView, self).get_initial()
initial["extra_field"] = self.request.user.extra_field
return initial
def update_settings(self, form):
super(SettingsView, self).update_settings(form)
profile = self.request.user.userprofile
profile.extra_field = form_cleaned_data['extra_field']
profile.save()
class SignupView(account.views.SignupView):
form_class = SignupForm
def after_signup(self, form):
profile = self.created_user.userprofile
profile.extra_field = form_cleaned_data['extra_field']
profile.save()
super(SignupView, self).after_signup(form)
Once everything is in place, it should work nicely (hopefully).
I struggled with this topic for about a year off and on until I finally found a solution I was happy with, and I know exactly what you mean by "there is a lot out there, but it doesn't work". I had tried extending the User model in different ways, I had tried the UserProfile method, and some other 1-off solutions as well.
I finally figured out how to simply extend the AbstractUser class to create my custom user model which has been a great solution for many of my projects.
So, let me clarify one of your comments above, you really shouldn't be creating a link between 2 models, the generally accepted "best" solution is to have one model which is inherited from AbstractUser or AbstractBaseUser depending on your needs.
One tricky thing that got me was that "Extending the User Model" did not get me where I wanted and I needed to Substitute the User Model, which I'm sure you've seen/read multiple times, but possibly not absorbed it (at least I know I didn't).
Once you get the hang of it, there's really not that much code and it's not too complicated either.
# models.py
from django.contrib.auth.models import AbstractUser
from django.db import models
class User(AbstractUser):
'''
Here is your User class which is fully customizable and
based off of the AbstractUser from auth.models
'''
my_custom_field = models.CharField(max_length=20)
def my_custom_model_method(self):
# do stuff
return True
There are a couple things to look out for after this, some of which came up in django 1.7.
First of all, if you want the admin page to look like it did before, you have to use the UserAdmin
# admin.py
from django.contrib import admin
from django.contrib.auth import get_user_model
from django.contrib.auth.admin import UserAdmin
# Register your models here.
admin.site.register(get_user_model(), UserAdmin)
The other thing is that if you're wanting to import the User class in a models file, you have to import it from the settings and not with get_user_model(). If you run into this, it's easy to fix, so I just wanted to give you a heads up.
You can check out my seed project I use to start projects to get a full but simple project that uses a Custom User Model. The User stuff is in the main app.
From there all the Registration and Login stuff works the same way as with a normal Django User, so I won't go into detail on that topic. I hope this helps you as much as it has helped me!
I try to avoid to extend the user model as explained in the django docs.
I use this:
class UserExtension(models.Model):
user=models.OneToOneField(User, primary_key=True)
... your extra model fields come here
Docs of OneToOneField: https://docs.djangoproject.com/en/1.7/topics/db/examples/one_to_one/
I see these benefits:
the same pattern works for other models (e.g. Group)
If you have N apps, every app can extend the model on his own.
Creating the UserExtension should be possible without giving parameters. All fields must have sane defaults.
Then you can create a signal handler which creates UserExtension instances if a user gets created.
I prefer extend the User model. For example:
class UserProfile(User):
def __unicode__(self):
return self.last_name + self.first_name
department = models.CharField(max_length=100)
class SignupForm(forms.Form):
username = forms.CharField(max_length=30)
first_name = forms.CharField(max_length=30)
last_name = forms.CharField(max_length=30)
department = forms.CharField(label="Department", max_length=100)
To save the data
form = UserRegistrationForm(request.POST)
if form.is_valid():
client = UserProfile()
client.username = username
client.set_password(password)
client.first_name = first_name
client.department = department
client.save()
check how are you saving the data after validate the form
I want my models to have order field, which will contain order of an item among all items of its kind.
And I want to use choices within that IntegerField, which would contain all the numbers of currently existing items in that table.
So it would need to be dynamic choices.
How do I load all existing "order" values of all existing items in a table, and use this list for choices?
It sounds like you want to build a manager for your model:
models.py
from django.db import models
class OrderManager(models.Manager):
def order_choices(self):
return [(i, i) for i in OrderModel.objects.values_list('order', flat=True)]
class OrderModel(models.Model):
objects = OrderManager()
order = models.IntegerField()
class Meta:
ordering = ['order']
def __unicode__(self):
return '%i' % self.order
forms.py
from django import forms
from yourapp.models import OrderModel
class OrderModelForm(forms.ModelForm):
order = forms.ChoiceField(choices=OrderModel.objects.order_choices())
class Meta:
model = OrderModel
admin.py
from django.contrib import admin
from yourapp.forms import OrderModelForm
from yourapp.models import OrderModel
class OrderModelAdmin(admin.ModelAdmin):
form = OrderModelForm
admin.site.register(OrderModel, OrderModelAdmin)
Edit
Managers are use to make general model queries without having an instance of a model object. If you don't understand the concept of managers, you can still refactor the code out of the manager class, stick it somewhere else and import that function across your code. Managers allow you to abstract custom general queryset that you can reuse. See more details https://docs.djangoproject.com/en/dev/topics/db/managers/
The code without the manager will look like
views.py or some other file
from app.models import OrderModel
def order_choices():
return [(i, i) for i in OrderModel.objects.values_list('order', flat=True)]
From anywhere in your code, if you want to reuse the above multiple times:
from app.views import oder_choices
order_choices()
as opposed to:
from app.models import OderModel
OrderModel.objects.order_choices()
If you only want to use the above once, you can leave it in the forms.py as shown in the other answer. It's really up to you on how you want to refactor your code.
Dont add the choices directly to the model, add them to a form represnting the model later, by overriding the field with a set of choices.
than, do something like:
class MyForm(..):
myfield_order_field = IntegerField(choices = [(i,i) for range(MyModel.objects.count)])
class Meta():
model = MyModel
if you want to use it in the admin, add to your Admin Class:
class MyModelAdmin(admin.ModelAdmin):
...
form = MyForm
it will override this field in the admin too.
Lets say I have the following two django (1.3) models
from django.db import models
class Patient(models.Model):
name = models.CharField('Name', max_length=50)
class Address(models.Model):
town = models.CharField('Town/Village', max_length=50)
patient = models.OneToOneField(Patient, related_name='address')
Now when i try to serialize a Patient model instance to JSON using django's serializers, the resulting JSON string does'nt have the address details with it (it's unable to traverse through the reverse direction of One-to-one relation)
This happens event if I use select_related('address') to populate the address object into the cache.
i.e.
from django.core import serializers
>>> print serializers.serialize('json',[Patient.objects.select_related('address').get(id=1)])
Is there are way I can get around this problem?
This problem came up in the project I am currently developing. Here is the solution we were going to use before we decided to just extend the Django serializer ourselves. This should work just fine for your needs though.
To solve the problem with out getting your hands dirty I would recommend wadofstuff's Django Full Serializers.
After getting it setup using the wiki solving your example would look something like this:
You need to add a method to your model which returns a python representation of the QuerySet.
from django.db import models
from django.core import serializers
class Patient(models.Model):
name = models.CharField('Name', max_length=50)
def extra_address(self):
return serializers.serialize('python', self.address.all())
class Address(models.Model):
town = models.CharField('Town/Village', max_length=50)
patient = models.OneToOneField(Patient, related_name='address')
Then you can add the method to the list of extras taken by the more robust serializer.
from django.core import serializers
print serializers.serialize('json', Patient.objects.all(), extras=('extra_address',))
An extras key will be added to the dictionary and will have whatever extra pieces of information you needed in it.
I have a model that has a ForeignKey to the built-in user model in django.contrib.auth and I'm frustrated by the fact the select box in the admin always sorts by the user's primary key.
I'd much rather have it sort by username alphabetically, and while it's my instinct not to want to fiddle with the innards of Django, I can't seem to find a simpler way to reorder the users.
The most straightforward way I can think of would be to dip into my Django install and add
ordering = ('username',)
to the Meta class of the User model.
Is there some kind of monkeypatching that I could do or any other less invasive way to modify the ordering of the User model?
Alternatively, can anyone thing of anything that could break by making this change?
There is a way using ModelAdmin objects to specify your own form. By specifying your own form, you have complete control over the form's composition and validation.
Say that the model which has an FK to User is Foo.
Your myapp/models.py might look like this:
from django.db import models
from django.contrib.auth.models import User
class Foo(models.Model):
user = models.ForeignKey(User)
some_val = models.IntegerField()
You would then create a myapp/admin.py file containing something like this:
from django.contrib.auth.models import User
from django import forms
from django.contrib import admin
class FooAdminForm(forms.ModelForm):
user = forms.ModelChoiceField(queryset=User.objects.order_by('username'))
class Meta:
model = Foo
class FooAdmin(admin.ModelAdmin):
form = FooAdminForm
admin.site.register(Foo, FooAdmin)
Once you've done this, the <select> dropdown will order the user objects according to username. No need to worry about to other fields on Foo... you only need to specify the overrides in your FooAdminForm class. Unfortunately, you'll need to provide this custom form definition for every model having an FK to User that you wish to present in the admin site.
Jarret's answer above should actually read:
from django.contrib.auth.models import User
from django.contrib import admin
from django import forms
from yourapp.models import Foo
class FooAdminForm(forms.ModelForm):
class Meta:
model = Foo
def __init__(self, *args, **kwds):
super(FooAdminForm, self).__init__(*args, **kwds)
self.fields['user'].queryset = User.objects.order_by(...)
class FooAdmin(admin.ModelAdmin):
# other stuff here
form = FooAdminForm
admin.site.register(Foo, FooAdmin)
so the queryset gets re-evaluated each time you create the form, as opposed to once, when the module containing the form is imported.