Use to_field if specified in ForeignKey

[manelclos]

No description provided.

[manelclos]

Fixes #204

[bmihelac]

@manelclos is it any reason not to use

field = f.rel.field_name

instead of f. to_fields lines?

[bmihelac]

I do not have any experience with using to_field, so comment above may be dumb

[manelclos]

I started looking into this, but run out of time. On my TODO list.

We should start using related_field instead for django >= 1.9:
https://github.com/django/django/blob/901dc90db0d95ddcd9a7d9608c8158cb9dbd824c/django/db/models/fields/__init__.py#L244

[kellerkind]

I added @manelclos hint to export from to_field attribute to work in my code. Thanks for this!
Also to mention that resolving foreign model should be done via related_model since 1.8.

--- a/import_export/resources.py
+++ b/import_export/resources.py
@@ -676,8 +676,11 @@ class ModelResource(six.with_metaclass(ModelDeclarativeMetaclass, Resource)):
         result = functools.partial(widgets.ManyToManyWidget,
                                    model=f.rel.to)
     if internal_type in ('ForeignKey', 'OneToOneField', ):
+            field = 'pk'
+            if f.remote_field.field_name:
+                field = f.remote_field.field_name
         result = functools.partial(widgets.ForeignKeyWidget,
-                                       model=f.rel.to)
+                                       model=f.related_model, field=field)
     if internal_type in ('DecimalField', ):
         result = widgets.DecimalWidget
     if internal_type in ('DateTimeField', ):

[manelclos]

#672 fixes this the correct way