dictionary in django python

In the follwoing code Maps.objects.all() returns all the objects in the tables and get description will return two variables namely name,description.

Now my question i am constructing a dicetionary.If the nam开发者_开发问答e is not in the dictionary then i should add it.How this should be done.

EDIT This needs to be done on python2.4

  labels = {}
  maps Maps.objects.all()
  for lm in maps:
     (name,description) = getDescription(lm.name,lm.type)
     if name not in labels:
        labels.update({name,description})

From what I understand, you're trying to assign a value to a key in a dictionary if it doesn't exist. Here's a helpful page for dictionaries.

Now, to address your question, this should do what you want:

labels = {}
maps = Maps.objects.all()
for lm in maps:
    name, description = getDescription(lm.name, lm.type)
    if name not in labels:
        labels[name] = description

you should use defaultdict

http://docs.python.org/library/collections.html

import collections

labels = collections.defaultdict(list)
maps = Maps.objects.all()
for lm in maps:
    name, description = getDescription(lm.name, lm.type)
    labels[name].append(description)

A much better way to do this in a single line:

labels = dict(Maps.objects.values_list('name', 'description'))