Hey Léon,
ChoiceField is a form field, not a table column—maybe you're thinking
about CommaSeparatedIntegerField? You could use that and hardcode
which categories represent which ids in your python code.
http://docs.djangoproject.com/en/dev/ref/models/fields/#commaseparatedintegerfield
On the other hand, the standard way of representing an object and its
categories in SQL is to use a ManyToMany relation. This approach
easily handles everything you want to do in a much easier to manage
format, and it's unlikely that you'll need to worry about "bloat"—
optimizing how you serve web pages, static files, caching, etc. will
give you *many* more gains than holding off from adding another table
to your db.
To setup your category, you can add something like this to your models
file (above your photos model):
class Category(models.Model):
title = models.CharField(max_length=100)
slug = models.SlugField(unique=True)
class Admin:
pass
and then inside your photos model add a new column:
categories = models.ManyToManyField(Category, blank=True)
-Peter
On Sep 9, 11:54 am, Léon Dignòn <[email protected]> wrote:
> Hello,
>
> let's assume we have a model for photos with the fields id, user,
> photo. Any user should be able to categorize his foto with a given
> number of categories, e.g. person, car, building. In future it's
> possible that I add more categories.
>
> My question is whether the new category field should be a ChoiceField,
> or a ForeignKey?
>
> I would prefer a ChoiceField because
> - I am 99% sure that there won't be new categories.
> - the only person who maybe adds a new category will be me.
> - another model would bloat up my database and my models.py
>
> But maybe I should use a ForeignKey because,
> - I don't have to edit the model/table.
> - it's easier to add a choice to a table than in the source code.
> - because values in databases should be atomic.
>
> Otherwise, assuming that syncdb can't handle adding new choices to an
> existing table, adding a choice directly in the database application
> (MySQL, PostgreSQL) is no problem. Removing a choice won't happen.
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