Admin site and read only field 'language_code' in Inlines...

[tarak]

I made an app where translated entries are added by using fixtures.
I wanted to integrate the app in the admin site, but only to see what
translations are available, so I just set readonly_fields on the admin inline
to contain the field 'language_code'. And it raised an error...

Reproducing the error:

My models.py looks like this:

from django.db import models
from django.utils.translation import ugettext_lazy as _
from multilingual_model.models import MultilingualModel
from multilingual_model.models import MultilingualTranslation


class MyModelTranslation(MultilingualTranslation):
    parent = models.ForeignKey('MyModel',
                               related_name='translations')
    name = models.CharField(max_length=200)

    class Meta:
        ordering = ['language_code']
        unique_together = ('parent', 'language_code')


class MyModel(MultilingualModel):
    code = models.CharField(db_index=True, max_length=16)

    class Meta:
        ordering = ['code']

    def __unicode__(self):
        u = self.unicode_wrapper('name', default=_('Unnamed'))

My admin.py looks like this:

from django.contrib import admin
from django.utils.translation import ugettext_lazy as _

from multilingual_model.admin import TranslationTabularInline

from myapp.models import MyModel, MyModelTranslation


class MyModelTranslationInline(TranslationTabularInline):
    extra=0
    can_delete = False
    model = MyModelTranslation
    readonly_fields = ('name', 'language_code')


class MyModelAdmin(admin.ModelAdmin):
    inlines = [MyModelTranslationInline]

admin.site.register(MyModel, MyModelAdmin)

This raises a KeyError because the field 'language_code' is not available in the
form:

Django Version: 1.5.dev20121025064951
Exception Type: KeyError
Exception Value: 'language_code'
Exception Location: /usr/local/lib/python2.7/dist-packages/multilingual_model/forms.py in _construct_available_languages, line 56
Python Executable: /usr/bin/python
Python Version: 2.7.3