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Django: Refer to User objects in fixture for another model

To avoid the XY problem, I will describe my problem and my attempted solution separately.
My problem
I have an Appointment model which I want to write fixtures for. There is a one-to-many mapping from the Django User model to the Appointment model (every appointment has only one client, but a client can have multiple appointments).
I know I can hard code the primary key for the Users in my appointment fixtures, but would be a brittle solution. Hard coding the foreign keys also compromises the readability of my fixtures.
My attempted solution
I looked at this question, which has an answer linking to Django documentation for natural keys. However, I ran into a problem attempting to use this approach.
I believed I could create a proxy model for the User model, so I could create a custom Manager for natural keys. Here is my proxy model:
class UserProxy(User):
objects = UserManager # The UserManager class's code is omitted
class Meta:
proxy = True
unique_together = [['username']]
(If the UserManager class's code is relevant, please let me know in a comment, and I will add it.)
However, when I run manage.py makemigrations, I get this error:
ERRORS:
accounts.UserProxy: (models.E016) 'unique_together' refers to field 'username' which is not local to model 'UserProxy'.
HINT: This issue may be caused by multi-table inheritance.
I understand this error message: the username field belongs to the User model, not to the UserProxy model.
My questions
Is my proxy model approach a good approach? If it is not, what should I do instead?
If my proxy model approach is a good approach, how can I correctly refer to the User model's username field in my unique_together list?

Django raw_id_fields read_only permission

I have this Django project that I'm working on, which won't allow users to select an entry (User entries) on the raw_id_fields popup, if they don't have change permissions (which they can't have at all). That's really weird cause that doesn't happen with the select tag list if I remove the raw_id_fields attribute on my ModelForm class at admins.py.
How can this permission behavior be consistent if it changes according to a different interface setting? I mean, user only have permission to select users on the form if they are displayed as a select tag. It seems to me that it's a big consistency failure with the way Django permissions was designed, which, in my opinion, should have native can_view permission, in addition to can_|add, change, delete.
While googling around I found a few topics discussing this matter, but all of them end up with some really painful solutions that don't seem straightforward to me. I wonder if something so simple could have a straightforward solution that won't require lots of workarounds.
Here is an example that looks like my actual code:
models.py
class Project(models.Model):
manager = models.ForeignKey(User)
...
admins.py
class ProjectAdmin(admin.ModelAdmin):
raw_id_fields = ['manager',]
...

As you've said, this is really weird. Thats why I've opted to "extend" the django admin to my specific requirements sometimes.
The easiest way to meet this goal is by overriding the has_change_permission of the referenced ModelAdmin
As you have the request object as an argument of the method, you can evaluate:
if the request comes from a raw_id_field or not
if the user has permissions to see that models or not
any other constraint you have
A simple prototype for the method:
def has_change_permission(self, request, obj=None):
if obj is None and '_popup' in request.GET:
return True
return super(MyAdmin, self).has_change_permission(request, obj)

django auth ldap with custom user model

I'm trying to use django auth ldap (v1.1.7) with a custom user model and, while I have everything else taken care of, I still run into a familiar error message that I just don't know how to fix.
Running python manage.py syncdb returns:
CommandError: One or more models did not validate:
django_auth_ldap.testprofile: 'user' defines a relation with the model 'auth.Use
r', which has been swapped out. Update the relation to point at settings.AUTH_US
ER_MODEL.
My question here is - where can I find django_auth_ldap.testprofile and update the relation, to fix the issue?
Thanks in advance for helping me out.
L.E.: Ok, after a little googleing, i found out that this testprofile is located in django_auth_ldap/models.py and get this: I searched through all of my files and found the file, modified it to point to settings.AUTH_USER_MODEL and still I receive the same error.
Can anyone please help me out with this issue?

This is the part of django_auth_ldap's models.py -
class TestProfile(models.Model):
"""
A user profile model for use by unit tests. This has nothing to do with the
authentication backend itself.
"""
user = models.OneToOneField('auth.User') # <-- here is the trouble
is_special = models.BooleanField(default=False)
populated = models.BooleanField(default=False)
You cannot fix it unless you fix this part of the code and do as said in Django documentation -
Instead of referring to User directly, you should reference the user
model using django.contrib.auth.get_user_model(). This method will
return the currently active User model – the custom User model if one
is specified, or User otherwise.
And I wont recommend modifying the 3rd party packages yourself. If you can, go suggest the change to the developer, or send them a pull request. Once it's accepted, update the package.

Django - permissions and profiles

I have a couple of different profiles. I want to associate permissions with these profiles. I've done so like this:
class StudentProfile(UserProfile):
school = models.CharField(max_length=30)
class Meta:
permissions = (
("is_student","Can access student pages"),
)
however, when I try and check if that permission exists using has_perm on that profile object, I get an error "'StudentProfile' object has no attribute 'has_perm'" am I not supposed to check for permissions in this way? I've read the docs and that's what I thought I was supposed to do
Edit: After reading the docs again, it seems that has_perm is a method belonging to Users and NOT their profiles. However, when I try to show the permissions:
print user.get_all_permissions()
I get an empty set. Shouldn't I see something like "appname.is_student"

.has_perm is a method on the User object, not on a UserProfile object. If you are trying to validate that a user has the permission has_student, you'd need to do something like this:
user.has_perm('profiles.is_student')
assuming that your StudentProfile model is in a profiles application.
EDIT: To address your rephrased question, you should assign permissions the normal way, either to the group or to a particular user, and use User.has_perm. Your latter example goes completely against the point of the Django permission system.

Set admin username to input field at Django admin

I'm developing a system based on Django admin. So all models could be edited also only from admin site. Model has a char field 'user'. I want to set current logged in admin username (or firstname, or lastname) as default value to 'user' field. How could I implement this?
Default values are set as parameters when defining model fields, so I guess no request object could be recieved? Maybe I should set the value when creating instance of model (inside init method), but how I could achieve this?

I found this recipe helpful: http://code.djangoproject.com/wiki/CookBookNewformsAdminAndUser

This is how you do it on the form level and not the save http://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.formfield%5Ffor%5Fforeignkey