Django: Filtering a ModelForm field

So something what should be so relatively easy can turn out to be quite hard when you don't know where to go for the answer. Generally the #django channel on IRC is an awesome help, but this morning I felt invisible so I can too keep digging. Finally I found my answer in code from another project.

Here's the situation. I'm creating a budget system. When you add or import transactions from your bank, you need to tell it what bank account the transactions are associated with. I have the following models: Bank, BankAccount, Transaction. Transaction has a foreign key to BankAccount.

I have a ModelForm named AddTransactionForm. The problem was that when I went to add a transaction, it would show me all the accounts of other users. I needed to somehow filter the queryset that was applied to the account foreign key. I couldn't find this anywhere in the docs, and like I mentioned, no one was even acknowledging me in IRC, which is rare. I finally found something similar I did for HouseSheet.com. Here was is my "fixed" form class:

class AddTransactionForm(ModelForm):
    def __init__(self, user, *args, **kwargs):
        super(AddTransactionForm, self).__init__(*args, **kwargs)
        self.fields['account'] = forms.ModelChoiceField(queryset=BankAccount.objects.filter(user=user))


    class Meta:
        model = Transaction
        exclude = ('envelope',)

So now, when I call this, I just need to pass in the the logged in user to show only that user's accounts like so: form = ImportForm(user=request.user)

I think my biggest problem with this was I haven't yet mastered the python language so I wasn't sure how to pass in the user object I need to filter on.