django-hvad - how should I set a translated field value while saving a model instance?

django, django-hvad, django-models, translation

Solution

The following answer assumes that you are using the admin system to auto-generate `slug` from `title`. This may or may not be your exact situation but it may be relevant.

This is an extension of the explanation within the Django-hvad project pages.

The way to implement your feature is within the the `admin.py` file within your app. You need to extend the `__init__()` method of the `TranslatableAdmin` class.

Say, for example, your model is called `Entry`. The simplified code in `models.py` could be along the lines of the following:

from django.db import models
from hvad.models import TranslatableModel, TranslatedFields

class Entry(TranslatableModel):
    translations = TranslatedFields(
        title=models.CharField(max_length=100,),
        slug=models.SlugField(),
        meta={'unique_together': [('language_code', 'slug')]},
    )
    def __unicode__(self):
        return self.lazy_translation_getter('title')

Your corresponding `admin.py` file should then be as follows:

from django.contrib import admin

from hvad.admin import TranslatableAdmin

from .models import Entry

class EntryAdmin(TranslatableAdmin):
    def __init__(self, *args, **kwargs):
        super(EntryAdmin, self).__init__(*args, **kwargs)
        self.prepopulated_fields = {'slug': ('title',)}

admin.site.register(Entry, EntryAdmin)

Problem

Background: I use `django-hvad` and have a `TranslatableModel`. In its `TranslatedFields` I have a `slug` attribute which should be automatically created using the `title` attribute while saving the model. Problem: It is difficult to set the value of one of the `TranslatedFields` while saving the instance. A solution that works is to override the `save_translations` method of my `TranslatableModel` as follows. Only the second last line differs from the original: ``` @classmethod def save_translations(cls, instance, **kwargs): """ The following is copied an pasted from the TranslatableModel class. """ opts = cls._meta if hasattr(instance, opts.translations_cache): trans = getattr(instance, opts.translations_cache) if not trans.master_id: trans.master = instance # The following line is different from the original. trans.slug = defaultfilters.slugify(trans.title) trans.save() ``` This solution is not nice, because it makes use of copy and paste. Is there a better way to achieve the same?

Original source