[Not solved] formfield_for_foreignkey difficulty

On 27/11/2015 8:38 AM, Mike Dewhirst wrote:
> On 27/11/2015 8:19 AM, Mike Dewhirst wrote:
>> On 26/11/2015 11:24 PM, Mike Dewhirst wrote:
>>> I have formfield_for_foreignkey working for a couple of fields in my
>>> substance model but find a brick wall when I try to restrict choices in
>>> an inline m2m foreign key.
>>
>> It was late last night and I forgot to mention Django 1.8.7 Admin,
>> Python 3.4 and 2.7 running on Windows 8.1 and Ubuntu 12.04 and 14.04.
>>
>> In the admin looking at a substance, Ingredients can be added
>> successfully from a drop-down list but I'm trying to restrict choices in
>> that list. Here is my failing attempt in IngredientsInline() ...
>>
>> def formfield_for_foreignkey(self, db_field, request, **kwargs):
>> """Limit choices for 'ingredient' field """
>> company = get_user_company(request)
>> if db_field.name == 'ingredient':
>> kwargs["queryset"] = Substance_Ingredients.objects.filter(
>> Q(ingredient__division__company=company))
>> return super(SubstanceAdmin, self).formfield_for_foreignkey(
>> db_field, request, **kwargs)
>
> The last line was wrong. This works ... (Yay! :)
>
> return super(SubstanceAdmin.IngredientsInline,
> self).formfield_for_foreignkey(db_field, request, **kwargs)

It doesn't work at all. It only shows existing ingredients. When I try
to add an ingredient to make a new mixture the drop-down list is empty.

I tried replacing the kwargs stanza with this ...

kwargs["queryset"] = Substance.objects.filter(
Q(substance__division__company=company))

... which ought to work but no luck.

Any ideas?

Thanks

Mike


>
>
>
>>
>> BTW, ingredient in Substance_Ingredients (see below) is a substance,
>> Substance has a foreign key to Division which in turn has a foreign key
>> to Company
>>
>>>
>>> The m2m relation is substance<-m2m->substance where any substance can be
>>> an ingredient in a mixture (also a substance).
>>>
>>> The through table is ...
>>>
>>> class Substance_Ingredients(models.Model):
>>> substance = models.ForeignKey('Substance', null=True, blank=True,
>>> related_name='base_substance')
>>> ingredient = models.ForeignKey('Substance', null=True, blank=True,)
>>> proportion = models.DecimalField(null=True, blank=True,)
>>>
>>> Is that a limitation in the admin or should I try harder?
>>>
>>> Thanks
>>>
>>> Mike
>>>
>>
>

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