Configurable Model Form

forms.py

from django import forms


class ConfigurableModelForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(ConfigurableModelForm, self).__init__(*args, **kwargs)
        opts = self.Meta
        if hasattr(opts, 'field_conf'):
            self.update_fields(opts.field_conf)

    def set_field_attr(self, field, attr, val):
        setattr(self.fields[field], attr, val)

    def update_field(self, field, conf):
        for attr, val in conf.iteritems():
            self.set_field_attr(field, attr, val)

    def update_fields(self, field_conf):
        for field, conf in field_conf.iteritems():
            self.update_field(field, conf)

usage.py

from .forms import ConfigurableModelForm


class MyForm(ConfigurableModelForm):
    class Meta:
        model = MyModel
        fields = ['email']
        field_conf = {
            'email': {
                'error_messages': {'unique': 'My awesome error message for violating unique values'},
                'required': False,
            }
        }