Whoops, I referenced the docs for the Model save() function, not the
ModelForm save() function. The signatures should be updated:
def save(self, commit=True):
rather than:
def save(self, *args, **kwargs):
The super() call would also need to be modified accordingly:
def save(self, commit=True):
do_something_with_extra_fields()
super(ModelFormMixin, self).save(commit=commit) # Call the "real"
save() method.
https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#the-save-method
-James
On Sun, Nov 16, 2014 at 12:31 AM, James Schneider <jrschneide...@gmail.com>
wrote:
> I understand that the the 'extra fields' are not part of the main model.
> However, without either providing a save() method definition somewhere,
> those fields will never be saved. Take the example I posted previously:
>
> class ModelFormMixin(forms.ModelForm):
> extra_field_1 = forms.CharField(required=False)
> extra_field_2 = forms.CharField(required=False)
>
> class Meta:
> fields = ('extra_field_1', 'extra_field_2')
>
> class ModelFormA(ModelFormMixin):
>
> class Meta(ModelFormExtraFields.Meta):
> model = ModelA
> fields = ModelFormExtraFields.Meta.fields + ('email', 'blah')
>
>
> I've renamed the ModelForm containing the extra fields to ModelFormMixin
> to make it easier to distinguish, and removed the field definitions in
> ModelFormA since they aren't needed if those fields are defined on the
> model itself. If you copy/pasted the example above, created a template with
> a "<form method=post>{{form.as_p}}{% csrf_token %}<button
> type='submit'>Submit</button></form>" in it (or something to that effect),
> you would see a working form with all 4 fields mentioned above
> (extra_field_1, extra_field_2, email, and blah).
>
> If you were to submit that form, only the values entered for email and
> blah will be saved to ModelA. The two extra_field_* fields would be
> discarded/ignored, since they are not part of ModelA.
>
> You would need to define a save() method within the mixin in order to
> actually do anything with those fields (assuming it would be the same
> action every time, whether it is saving the values to another model in the
> database, sending an email, displaying a message, etc.). So, your mixin
> should really look like this:
>
> From:
> https://docs.djangoproject.com/en/dev/topics/db/models/#overriding-model-methods
>
> class ModelFormMixin(forms.ModelForm):
> extra_field_1 = forms.CharField(required=False)
> extra_field_2 = forms.CharField(required=False)
>
> class Meta:
> fields = ('extra_field_1', 'extra_field_2')
>
> def save(self, *args, **kwargs):
> do_something_with_extra_fields()
> super(ModelFormMixin, self).save(*args, **kwargs) # Call the
> "real" save() method.
>
>
> This way, when the save() method is executed on ModelFormA, it will use
> the inherited save() method from your Mixin, which will do something with
> your extra_fields, and will call the save() method from the ModelForm
> class, which will ultimately save the fields related to ModelA.
>
> To answer your question, you probably could add the fields via the
> __init__() method, but that only makes the fields available for display in
> the form object, you would still have the issue of the values from the
> extra fields being saved once a submitted form is processed. With the
> strategy above, you would write the Mixin once, and have your ModelForms
> inherit from it, and update the Meta.fields to include the fields from the
> Mixin. This is, of course, assuming that the same action will be taken on
> the extra fields every time, otherwise you'll need to override save() on
> the ModelFormA class, and add the custom actions for the extra fields
> there.
>
> I guess the key take-away is that there is more to it than simply adding
> the field to the form so it can be displayed. You also need to determine
> how to process the fields after they are submitted.
>
> Hope that clarifies rather than confuses.
>
> -James
>
>
>
>
> On Sat, Nov 15, 2014 at 11:43 AM, Michael <michael.palumb...@gmail.com>
> wrote:
>
>> Thanks James.
>>
>> Maybe I did not well mention that the extra fields are not fields of the
>> Model. I do not want Django to try to save them in the model.
>> Also, I did not make FormA inherits from forms.ModelForm because there is
>> no Model to define and I want to use these extra fields with any type of
>> forms: ModelForm as well as normal Forms.
>>
>> Is there an issue to add them in the __init__ method?
>>
>>
>> Thanks
>>
>>
>>
>> Le samedi 15 novembre 2014 13:41:23 UTC-6, Michael a écrit :
>>
>>> Maybe I did not well mention that the extra fields are not fields of the
>>> Model.
>>> Also, I did not make FormA inherits from forms.ModelForm because there
>>> is no Model to define and I w
>>>
>>>
>>>
>>> Le samedi 15 novembre 2014 02:41:11 UTC-6, James Schneider a écrit :
>>>>
>>>> "Why does the following not give a final model form with 3 fields?
>>>> The two extra fields are not available. If I move them directly into
>>>> the model form, it works but I wanted to declare these fields in a separate
>>>> form because I plan on reusing them in several forms.
>>>> Is there a way to do that?"
>>>>
>>>> I also meant to answer this: The parent form with the 'extra' fields
>>>> needs to inherit from forms.ModelForm, not just forms.Form, otherwise the
>>>> child ModelForm is unhappy. You would also need to update the fields value
>>>> in Meta to include the fields from the parent form, but my example shows
>>>> that.
>>>>
>>>> Also, I didn't test this, but you may need to declare a save() function
>>>> in the parent form, otherwise your two fields will not be saved because
>>>> Django has no idea what to do with them. If these extra fields are going to
>>>> be saved using the same model as the rest of the model form, you would be
>>>> better off with inheriting from abstract models and leaving the modelform
>>>> alone.
>>>>
>>>> -James
>>>>
>>>> On Sat, Nov 15, 2014 at 12:25 AM, James Schneider <jrschn...@gmail.com>
>>>> wrote:
>>>>
>>>>> I think you're overcomplicating things. Check this out:
>>>>>
>>>>> https://docs.djangoproject.com/en/dev/topics/forms/
>>>>> modelforms/#form-inheritance
>>>>> http://chriskief.com/2013/06/30/django-form-inheritance/
>>>>>
>>>>> Try this:
>>>>>
>>>>> class ModelFormExtraFields(forms.ModelForm):
>>>>> extra_field_1 = forms.CharField(required=False)
>>>>> extra_field_2 = forms.CharField(required=False)
>>>>>
>>>>> class Meta:
>>>>> fields = ('extra_field_1', 'extra_field_2')
>>>>>
>>>>> class ModelFormA(ModelFormExtraFields):
>>>>> email = forms.CharField(required=False)
>>>>> blah = forms.CharField(required=False)
>>>>>
>>>>> class Meta(ModelFormExtraFields.Meta):
>>>>> model = ModelA
>>>>> fields = ModelFormExtraFields.Meta.fields + ('email', 'blah')
>>>>> # or as the last fields
>>>>> #fields = ('email', 'blah') + ModelFormExtraFields.Meta.fields
>>>>>
>>>>> I don't even really think the Meta class in ModelFormA even needs to
>>>>> inherit directly, so just having a straight Meta: class may save some
>>>>> keystrokes, but I didn't test that.
>>>>>
>>>>> -James
>>>>>
>>>>>
>>>>> On Fri, Nov 14, 2014 at 6:15 AM, Michael Palumbo <
>>>>> michael....@gmail.com> wrote:
>>>>>
>>>>>> Thanks for your response James.
>>>>>> I am not well familiar with the metaclasses, I do not really see how
>>>>>> to do it.
>>>>>>
>>>>>> What do you think of adding the fields in the init this way?
>>>>>>
>>>>>> extra_fields = {'extra1': forms.CharField(required=False), 'extra2':
>>>>>> forms.CharField(required=False)}
>>>>>>
>>>>>> class ModelFormA(forms.ModelForm):
>>>>>> def __init__(self, *args, **kwargs):
>>>>>> super(ModelFormA, self).__init__(*args, **kwargs)
>>>>>> for name, field in extra_fields.iteritems():
>>>>>> self.fields[name] = field
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>>
>>>>>> On Thu, Nov 13, 2014 at 11:38 PM, James Schneider <
>>>>>> jrschn...@gmail.com> wrote:
>>>>>>
>>>>>>> Modify your Meta class to include the extra fields on the model
>>>>>>> form. The Meta classes are not inherited.
>>>>>>>
>>>>>>> You may also need to override the save() method on your model form
>>>>>>> to actually save the contents of those extra fields in the inherited
>>>>>>> form.
>>>>>>>
>>>>>>> -James
>>>>>>> On Nov 13, 2014 6:32 PM, "Michael" <michael....@gmail.com> wrote:
>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> Why does the following not give a final model form with 3 fields?
>>>>>>>> The two extra fields are not available. If I move them directly
>>>>>>>> into the model form, it works but I wanted to declare these fields in a
>>>>>>>> separate form because I plan on reusing them in several forms.
>>>>>>>> Is there a way to do that?
>>>>>>>>
>>>>>>>> class FormA(forms.Form):
>>>>>>>> extra_field_1 = forms.CharField(required=False)
>>>>>>>> extra_field_2 = forms.CharField(required=False)
>>>>>>>>
>>>>>>>> class ModelFormA(FormA, forms.ModelForm):
>>>>>>>> class Meta:
>>>>>>>> model = ModelA
>>>>>>>> fields = ['email']
>>>>>>>>
>>>>>>>> Thanks
>>>>>>>> Mike
>>>>>>>>
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