Passing a model instance, not __unicode__ method in django
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I've got a django form that contains a join via a foreign key.  This is a foreign key to a very large table.  On the form, to prevent loading up a massive select that tends to crash browsers, I've got a jQuery autocomplete, which on each keystroke sends off the entered text.  This text is then searched in the table and suitable results are returned to be displayed.  The id is then passed to a hidden CharField when one is selected.  This hidden CharField is the widget for the ForeignKey relation.  When I try to save the form, I get an error that I need to be passing a model instance for the related model, which is fair enough.  I can't work out how to do this however.  I can take that id and do a `model.objects.get(pk=id_from_form)`, but if I replace the POST data with the result of this, I still get an error as I'm just passing the `__unicode__` method of the model.  I'm sure there's something I'm missing, but I can't see what it is.

Thanks.