Django set default form values

You can use Form.initial, which is explained here.

You have two options either populate the value when calling form constructor:

form = JournalForm(initial={'tank': 123})

or set the value in the form definition:

tank = forms.IntegerField(widget=forms.HiddenInput(), initial=123) 

Other solution: Set initial after creating the form:

form.fields['tank'].initial = 123