GeoDjango: Can I use OSMGeoAdmin in an Inline in the User Admin?

Question

Profile contains a PointField. I've used OSMGeoAdmin in the ProfileAdmin, here:

class ProfileAdmin(admin.OSMGeoAdmin):
    model = Profile

But can't figure out how to use it in an inline for display in the UserAdmin. I currently have this set up as below:

# User Admin, with Profile attached
class ProfileInline(admin.StackedInline):
    model = Profile
    can_delete = False
    verbose_name_plural = 'Profile'  # As only one is displayed in this view

class UserAdmin(UserAdmin):
    inlines = (
        ProfileInline,
    )

admin.site.unregister(User)
admin.site.register(User, UserAdmin)

Is it possible to use class OSMGeoAdmin in this situation?

Answer 1

This would be a good feature to request I guess.

As a workaround, you can take advantage of the fact that an InlineModelAdmin is quite similar to a ModelAdmin. Both extend BaseModelAdmin.

Inheriting from both StackedInline and ModelAdmin should not clash too much.

The only issue is that both __init__() methods take 2 positional arguments and call super().__init__() without arguments. So whatever the inheritance order, it will fail with TypeError: __init__() missing 2 required positional arguments: 'parent_model' and 'admin_site'

Fortunately, the InlineModelAdmin.__init__() method, the one we are interested in, is not really verbose nor complex (not too much super().__init__() calls in cascade).

Here is what it looks like in Django 1.9:

def __init__(self, parent_model, admin_site):
    self.admin_site = admin_site
    self.parent_model = parent_model
    self.opts = self.model._meta
    self.has_registered_model = admin_site.is_registered(self.model)
    super(InlineModelAdmin, self).__init__()
    if self.verbose_name is None:
        self.verbose_name = self.model._meta.verbose_name
    if self.verbose_name_plural is None:
        self.verbose_name_plural = self.model._meta.verbose_name_plural

And here is what its parent (BaseModelAdmin) looks like in Django 1.9

def __init__(self):
    overrides = FORMFIELD_FOR_DBFIELD_DEFAULTS.copy()
    overrides.update(self.formfield_overrides)
    self.formfield_overrides = overrides

Now let's put it all together:

from django.contrib.admin.options import FORMFIELD_FOR_DBFIELD_DEFAULTS

# User Admin, with Profile attached
class ProfileInline(OSMGeoAdmin, admin.StackedInline):
    model = Profile
    can_delete = False
    verbose_name_plural = 'Profile'  # As only one is displayed in this view

    def __init__(self, parent_model, admin_site):
        self.admin_site = admin_site
        self.parent_model = parent_model
        self.opts = self.model._meta
        self.has_registered_model = admin_site.is_registered(self.model)
        overrides = FORMFIELD_FOR_DBFIELD_DEFAULTS.copy()
        overrides.update(self.formfield_overrides)
        self.formfield_overrides = overrides
        if self.verbose_name is None:
            self.verbose_name = self.model._meta.verbose_name
        if self.verbose_name_plural is None:
            self.verbose_name_plural = self.model._meta.verbose_name_plural

class UserAdmin(UserAdmin):
    inlines = (
        ProfileInline,
    )

admin.site.unregister(User)
admin.site.register(User, UserAdmin)

It's not really a satisfying solution as it requires to copy/paste some code from django, which may be different within the version of Django you use, and might be a pain to maintain when upgrading Django. However it should work until it is included in Django as a mix-in or as an InlineModelAdmin.

Note: the code snippets above are taken from Django 1.9, you should browse github tags to find the snippets corresponding to your version.

Answer 2

Since Django admin fields use widgets, you can override the widget that's automatically set for a PointField using formfield_overrides. In this case, you can override all PointField instances to use the OSMWidget class like so:

from django.contrib.gis.forms.widgets import OSMWidget 

class ProfileInline(admin.StackedInline):
    model = Profile
    can_delete = False
    verbose_name_plural = 'Profile'  # As only one is displayed in this view
    formfield_overrides = {
        PointField: {"widget": OSMWidget},
    }