Geek Answers Handbook

Django: fields of reuse form without inheritance?

If I have two forms based on different base classes (e.g. Form and ModelForm), but I want to use multiple fields in both cases, can I reuse them with DRY?

Consider the following scenario:

class AfricanSwallowForm(forms.ModelForm):
    airspeed_velocity = forms.IntegerField(some_important_details_here)
    is_migratory = forms.BooleanField(more_important_details)

    class Meta:
        model = AfricanBird

class EuropeanSwallowForm(forms.Form):
    airspeed_velocity = forms.IntegerField(some_important_details_here)
    is_migratory = forms.BooleanField(more_important_details)

.... is there a way that I can simply reuse the airspeed_velocity and is_migratory fields? Imagine that I have a couple dozen of these types of shapes. The code will be soaked if I write them again and again.

(Suppose, for the purposes of this question, that I cannot or will not rotate airspeed and becomes migratory in the fields of the AfricanBird model.)

+5
source share
5 answers

factory -style?

def form_factory(class_name, base, field_dict):
    always_has = {
        'airspeed_velocity': forms.IntegerField(some_important_details_here),
        'is_migratory': forms.BooleanField(more_important_details)
    }
    always_has.update(field_dict)
    return type(class_name, (base,), always_has)

def meta_factory(form_model):
    class Meta:
        model = form_model
    return Meta

AfricanSwallowForm = form_factory('AfricanSwallowForm', forms.ModelForm, {
        'other' = forms.IntegerField(some_important_details_here),
        'Meta': meta_factory(AfricanBird),
    })

EuropeanSwallowForm = form_factory('EuropeanSwallowForm', forms.Form, {
        'and_a_different' = forms.IntegerField(some_important_details_here),
    })

factory , , ...

+1

aka mixins, , Form, ModelForm.

class SwallowFormFields:
    airspeed_velocity = forms.IntegerField( ... )
    is_migratory = forms.BooleanField( ... )

class AfricanSwallowForm(forms.ModelForm, SwallowFormFields):
    class Meta:
        model = AfricanBird

class EuropeanSwallowForm(forms.Form, SwallowFormFields):
    pass

UPDATE:

Django, __init__, :

class SwallowFormFields:
    airspeed_velocity = forms.IntegerField()
    is_migratory = forms.BooleanField()

class AfricanSwallowForm(forms.ModelForm):
    airspeed_velocity = SwallowFormFields.airspeed_velocity
    is_migratory = SwallowFormFields.is_migratory
    class Meta:
        model = AfricanSwallow

class EuropeanSwallowForm(forms.Form):
    airspeed_velocity = SwallowFormFields.airspeed_velocity
    is_migratory = SwallowFormFields.is_migratory

UPDATE

, - ...

airspeed_velocity = forms.IntegerField()
is_migratory = forms.BooleanField()

class AfricanSwallowForm(forms.ModelForm):
    airspeed_velocity = airspeed_velocity
    is_migratory = is_migratory
    class Meta:
        model = AfricanSwallow

class EuropeanSwallowForm(forms.Form):
    airspeed_velocity = airspeed_velocity
    is_migratory = is_migratory

UPDATE:

, DRY , .

, :

from django.forms.models import ModelForm, ModelFormMetaclass
from django.forms.forms import get_declared_fields, DeclarativeFieldsMetaclass
from django.utils.copycompat import deepcopy

class MixinFormMetaclass(ModelFormMetaclass, DeclarativeFieldsMetaclass):
    def __new__(cls, name, bases, attrs):

        # default __init__ that calls all base classes
        def init_all(self, *args, **kwargs):
            for base in bases:
                super(base, self).__init__(*args, **kwargs)
        attrs.setdefault('__init__', init_all)

        # collect declared fields
        attrs['declared_fields'] = get_declared_fields(bases, attrs, False)

        # create the class
        new_cls = super(MixinFormMetaclass, cls).__new__(cls, name, bases, attrs)
        return new_cls

class MixinForm(object):
    __metaclass__ = MixinFormMetaclass
    def __init__(self, *args, **kwargs):
        self.fields = deepcopy(self.declared_fields)

MixinForm :

class SwallowFormFields(MixinForm):
    airspeed_velocity = forms.IntegerField()
    is_migratory = forms.BooleanField()

class MoreFormFields(MixinForm):
    is_endangered = forms.BooleanField()

:

class EuropeanSwallowForm(forms.Form, SwallowFormFields, MoreFormFields):
    pass

class AfricanSwallowForm(forms.ModelForm, SwallowFormFields):
    class Meta:
        model = AfricanSwallow

?

  • , MixinForm
  • __init__, , __init__ MixinForm . ( .)
  • MixinForm.__init__ int

, Python django, . , , :)

!

+4

class SwallowForm(forms.Form):
    airspeed_velocity = forms.IntegerField()
    is_migratory = forms.BooleanField()

class AfricanSwallowForm(forms.ModelForm, SwallowForm):
    class Meta:
        model = AfricanSwallow

class EuropeanSwallowForm(forms.Form, SwallowForm):
    ...

. a >

, attr, .

languages_field = forms.ModelMultipleChoiceField(
        queryset=Language.objects.all(),
        widget=forms.CheckboxSelectMultiple,
        required=False
)

class FooLanguagesForm(forms.ModelForm):
    languages = languages_field

    class Meta:
        model = Foo
        fields = ('languages', )

, - . dict , , Meta.fields.

, :

genres_field = forms.ModelMultipleChoiceField(
        queryset=blah,
        widget=forms.CheckboxSelectMultiple,
        #required=False,
)

class FooGenresForm(forms.Form):
    genres = genres_field

, dict .

In [6]: f = FooLanguagesForm()

In [7]: f.fields
Out[7]: {'languages': <django.forms.models.ModelMultipleChoiceField object at 0x1024be450>}

In [8]: f2 = FooGenresForm()

In [9]: f2.fields
Out[9]: {'genres': <django.forms.models.ModelMultipleChoiceField object at 0x1024be3d0>}
0

IntegerField

class AirspeedField(forms.IntegerField):
    def __init__():
        super(AirspeedField, self).__init__(some_important_details_here)
0

More articles:


All Articles