Fix for #1778.

[explody]

This will set initial values for visible bulk-add form fields from query args.

Fixes:

#1778

This is a simple fix to allow bulk-addition of addresses to receive initial values set in the single-address-addition form, which are already passed as query args in the URL.

The approach I took is just to loop through the form's visible Meta fields, and build a dict of initial form field values from query args that match field names. (initial vals described here):

https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#providing-initial-values

Query args that don't match field names are ignored since we loop on meta fields, not the query args, and Django quietly ignores invalid initial values.

There are alternate approaches to comparing the fields but they seemed like micro optimizations and slightly less easy to read:

        fields = getattr(self.model_form._meta, 'fields', [])
        for field in set(fields).intersection(request.GET.keys()):
            if request.GET[field]:
                initial[field] = request.GET[field]