how to dynamically set visible fields of a django modelform? - django

I would like the visible fields of a ModelForm to be determined by the instance of the model class it is built upon.
The ModelForm is built upon the model protocol which has a method (protocol.visiblefields())which returns an array of strings corresponding to the fields to be made visible.
forms.py
class ListForm(ModelForm):
class Meta():
model = protocol
fields = []
views.py
newProtocol = protocol()
form = ListForm(instance=newProtocol)

You have a couple of options to do this, one is mostly in the view and the other is in the form __init__.
Option 1: Pop the fields after initializing the form. Although you would need to specify all fields in the form Meta and remove the ones you don't want in the view.
newProtocol = protocol()
form = ListForm(instance=newProtocol)
visible_fields = newProtocol.visiblefields()
for field in form.fields:
if field not in visible_fields:
form.fields.pop(field)
Option 2: Overwrite the __init__ method and pass the fields in. We include all fields and remove the ones we don't want.
forms.py
class ListForm(ModelForm):
class Meta:
model = protocol
fields = '__all__'
def __init__(self, *args, **kwargs):
visible_fields = kwargs.pop('visible_fields')
super(ListForm, self).__init__(*args, **kwargs)
for field in self.fields:
if field not in visible_fields:
self.fields.pop(field)
views.py
newProtocol = protocol()
form = ListForm(instance=newProtocol, visible_fields=newProtocol.visiblefields())

Related

modelformset_factory: display more fields for specific instances

I'm using a modelformset_factory to edit multiple instances of Product in the same form:
ProductFormSet = modelformset_factory(Product, fields=('code', 'state'))
form_products = ProductFormSet()
It works well.
But now I need to display an additional field of the Product model in the form but only for a specific instance of Product. I'm not sure if it can be done in a simple manner in Django. Is it possible to do so using a modelformset_factory?
You can specify the form in the modelformset_factory, so create a model form (in forms.py if you have one) override the __init__method to add extra fields.
I would move the fields from the formsetfactory arguments to the form
in forms.py (assuming you have one)
class ProductForm(forms.ModelForm):
model = Product
def __init__(self, *args, **kwargs):
super(ProductForm, self).__init__(*args, **kwargs)
if 'instance' in kwargs :
product = kwargs['instance']
# to add an extra field, add something like this
self.fields['extra_field'] = forms.CharField(max_length=30)
class Meta:
fields = ('code', 'state')
Then pass that to your modelformset factory with the form argument
ProductFormSet = modelformset_factory(Product, form=ProductForm )
form_products = ProductFormSet()

Django model form - Exclude a field that has no model field

I have a simple model form what I use through the admin interface. Some of my model fields store datas that require a bit more time to calculate (they come from other sites). So I decided to put an extra boolean field to the form to decide to crawl these datas again or not.
class MyModelForm(forms.ModelForm):
update_values = forms.BooleanField(required=False) #this field has no model field
class Meta:
model = MyModel
This extra field doesn't exist in the model because only the form needs it.
The problem is that I only want it to appear if it's an existing record in the database.
def __init__(self, *args, **kwargs):
super(MyModelForm, self).__init__(*args, **kwargs)
if self.instance.pk is None:
#remove that field somehow
I tried nearly everything. Exclude it, delete the variable but nothing wants to work. I also tried dynamically add the field if self.instance.pk is exists but that didn't work too.
Any idea how to do the trick?
Thanks for your answers.
You could subclass the form and add the extra field in the subclass:
class MyModelForm(forms.ModelForm):
class Meta:
model = MyModel
class MyUpdateModelForm(MyModelForm):
update_values = forms.BooleanField(required=False) #this field has no model field
class Meta:
model = MyModel
You can then override the get_form method of your admin, which is passed the current instance: get_form(self, request, obj=None, **kwargs)
Rather than removing the field in __init__ if instance.pk is not None, how about adding it if it is None? Remove the class-level declaration and just change the logic:
class MyModelForm(forms.ModelForm):
class Meta:
model = MyModel
def __init__(self, *args, **kwargs):
super(MyModelForm, self).__init__(*args, **kwargs)
if self.instance and self.instance.pk is not None:
self.fields['update_values'] = forms.BooleanField(required=False)

Django MultipleHiddenInput and ManyToManyField

Can a ManyToManyField inside a ModelForm use a forms.MultipleHiddenInput widget instead of the default forms.MultipleChoiceField? In the example below 'groups' is a ManyToManyField on the Model 'Test':
class TestSelectionForm(forms.ModelForm):
class Meta:
model = Test
fields = ('groups')
widgets = {
'groups': forms.MultipleHiddenInput()
}
def __init__(self, *args, **kwargs):
super(TestSelectionForm, self).__init__(*args, **kwargs)
self.fields['groups'].queryset = Group.objects.filter(...)
But no hidden input fields were rendered for this form. Am I missing something or is it just not possible to use MultipleHiddenInput together with a ManyToManyField? (Should I then just write the HTML for the hidden inputs inside the template or is there a different approach I could use from within the ModelForm)?

CBV Django Form View set data for ChoiceField

I'm using the Django Form View and I want to enter custom choices per user to my Choicefield.
How can I do this?
Can I use maybe the get_initial function?
Can I overwrite the field?
When I want to change certain things about a form such as the label text, adding required fields or filtering a list of choices etc. I follow a pattern where I use a ModelForm and add a few utility methods to it which contain my overriding code (this helps keep __init__ tidy). These methods are then called from __init__ to override the defaults.
class ProfileForm(forms.ModelForm):
class Meta:
model = Profile
fields = ('country', 'contact_phone', )
def __init__(self, *args, **kwargs):
super(ProfileForm, self).__init__(*args, **kwargs)
self.set_querysets()
self.set_labels()
self.set_required_values()
self.set_initial_values()
def set_querysets(self):
"""Filter ChoiceFields here."""
# only show active countries in the ‘country’ choices list
self.fields["country"].queryset = Country.objects.filter(active=True)
def set_labels(self):
"""Override field labels here."""
pass
def set_required_values(self):
"""Make specific fields mandatory here."""
pass
def set_initial_values(self):
"""Set initial field values here."""
pass
If the ChoiceField is the only thing you're going to be customising, this is all you need:
class ProfileForm(forms.ModelForm):
class Meta:
model = Profile
fields = ('country', 'contact_phone', )
def __init__(self, *args, **kwargs):
super(ProfileForm, self).__init__(*args, **kwargs)
# only show active countries in the ‘country’ choices list
self.fields["country"].queryset = Country.objects.filter(active=True)
You can then make your FormView use this form with like this:
class ProfileFormView(FormView):
template_name = "profile.html"
form_class = ProfileForm

django modelform and additional fields and their order

I have a modelform and im creating additional fields (that do not exist in model) for its form.
I know you can reorder the fields in modelform like it says in the docs.
But the problem is - i want the additional fields to be rendered BEFORE the other fields.
Is it possible to somehow reorder the fields of the form before rendering? How does form object keep track of the order of its fields anyway?
Alan
No matter. It seems i found answer already and this seems to do the trick, since i have added 2 additional fields:
def __init__(self, *args, **kwargs):
super(MyForm, self).__init__(*args, **kwargs)
self.build_fields()
l = len(self.fields.keyOrder)
for i in range(0,2):
f = self.fields.keyOrder[l-1]
self.fields.keyOrder.pop(l-1)
self.fields.keyOrder.insert(0, f)
This above was my initial fix. Later on i found out that it did not cut any more. Then i did this :
class AlertForm(forms.ModelForm):
class Meta:
model = Message
fields = model_fields
def __init__(self, *args, **kwargs):
super(AlertForm, self).__init__(*args, **kwargs)
self.build_fields()
newKeyOrder = []
newKeyOrder.append('field_that_had_to_be_first')
if typechange:
newKeyOrder.append('field_thats_sometimes_necessary')
newKeyOrder += model_fields
self.fields.keyOrder = newKeyOrder
The solutions above no longer works with django 2 (I don't know since when)...
But now, there's an ordered dict fields property on ModelForm that we can use to reorder the fields...
class MyForm(forms.ModelForm):
class Meta:
fields = ['model_field1', 'model_field2']
model = MyModel
extra_field = forms.CharField()
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
for k in self._meta.fields:
self.fields.move_to_end(k)
The fields attribute of your ModelForm`s Meta class define which fields to show and in which order.
Use the fields attribute of the ModelForm's inner Meta class. This attribute, if given, should be a list of field names to include in the form. The order in which the fields names are specified in that list is respected when the form renders them.