Question

I am trying to use a ModelChoiceField to get the values populated from an external database.

I have added an additional database in my setting.py and have set up a externaldb.py file in my app as follows:

from django.db import connections

def Location():

    rs = []

    cursor = connections['mydb'].cursor()
    cursor.execute("SELECT city FROM db.data_center WHERE removed is null;")
    zones = cursor.fetchall()

        for v in zones[::]:
            rs.append(v)

The using python manage.py shell I can do this

>>>from platform.externaldb import Location
>>>print Location()
>>>[(u'India-01',), (u'Singapore-01',), (u'Europe-01',)]

So I am getting values but how to I get that to appear in a drop down box.. This is my forms.py

forms.py

from platform.externaldb import Location

zone = forms.ModelChoiceField(Location(), label='Zone')

But this doesn’t work for me.. How do I do this so the 3 values appears in the ModelChoiceField drop down list?

Thanks – Oli

Answer 1

You could make use of the ChoiceField form field rather then the ModelChoiceField. The problem with using a ModelChoiceField is that it expects a QuerySet. The ChoiceField allows you to add items via a List instead.

locations = forms.ChoiceField(choices=Locations(), label="Zone")

EDIT

Previously, I had used the ModelChoiceField:

locations = forms.ModelChoiceField(queryset=Location.objects.all(), label="Zone")

which will work as long as Location is a Model (which I wasn’t sure of based on your code)