Question

I am new to Django and I am trying to build a data hierarchy that follows this pattern:

There will be several Communities – say Huntsville, Phoenix, and Madison.

Each of those communities will be able to have several distinct Categories. For example, Huntsville may have Hunting, fishing, and skiing – and Phoenix may have running, biking, and swimming. Then each of the particular categories will have a number of distinct detail views. I tried to make this happen with:

from django.db import models

class Community(models.Model):
    name = models.CharField(max_length=200) #arbitrary max length

class Category(models.Model):
    community = models.ForeignKey(Community)
    category = models.CharField(max_length=200) #arbitrary max length

class Detail_View(models.Model):
    category = models.ForeignKey(Category)
    detailView = models.CharField(max_length=200) #arbitrary max length
    website = models.CharField(max_length=200) #arbitrary max length

but it doesn’t really seem to be working the correctly and I can’t quite figure out why.

Any thoughts?

Answer 1

I’m not sure I fully understand the behavior you’re looking for, but I have some advice anyway.

First, it looks like you’re implementing a one-to-many when you really want a many-to-many.

Check out http://docs.djangoproject.com/en/1.3/ref/models/relations/

Per that link, use models.ManyToManyField instead of models.ForeignKey

Also if you meant to define this as a one-to-many, you probably don’t want Category to reference Community. Use the phrase “has a” or “has many” to determine this. Since a Community “has a” Category, the ForeignKey (or ManyToManyField) should be defined on the Community model, not the Category one.

I’d strongly recommend taking a look at the freely available Django Book project, especially the chapter on Advanced Models

Hope this helps!