Model form - How to change default ManyToMany widget? - django

Question

I use Django Model Form:
class Fruit(models.Model):
name = models.CharField(max_length=40)
class Box(models.Model):
user = models.ForeignKey(User)
name = models.CharField(max_length=199)
fruit = models.ManyToManyField(Fruit)
and forms.py:
class BoxModelForm(ModelForm):
class Meta:
model = Box
I have default django ManyToMany widget in form:
http://nov.imghost.us/ly5M.png
How can I change this to input (text type) and if I type into this input:
apple,banana,lemon - comma separated
this Fruit will be created?

Answer 1

As stated here in the documentation :https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#overriding-the-default-fields
You can add a widgets attribute to the Meta of your Modelform to change the default widgets used in the form.
In your case it would be something like this :
class BoxModelForm(ModelForm):
class Meta:
model = Box
widgets = {
'fruit': TheWidgetYouWantToUse(),
}
But actually for the behavior you want to achieve, you could proceed another way.
You should add an extra text field, and write the addition/removal of fruits in the save step, while checking the validity of the differents tags in the clean step.
class BoxModelForm(ModelForm):
fruit_selector = forms.TextField(
max_length=255,
tag = 'Whatever'
)
class Meta:
model = Box
fields = ['user','name']
def clean_fruit_selector(self):
data = self.cleaned_data['fruit_selector']
# Check that data are corrects ie the string is correctly formatted
# If not raise validation error
....
fruit_tags = data.split(",")
#Check that all tags are fruit or raise a validation error
...
return data #or only the list of correct tags
def save(self, commit=True):
instance = super(MyForm, self).save(commit=False)
# Compare the list of tags fruit_tags with self.instance.fruit.all()
....
# Take the right actions
if commit:
instance.save()
return instance
Look into this page for more details on how to change the field validation https://docs.djangoproject.com/en/dev/ref/forms/validation/
This is just a schematic.

Answer 2

django-taggit is a perfect app for this use case.
Define your models like this:
from taggit.managers import TaggableManager
from taggit.models import TagBase, GenericTaggedItemBase
class Fruit(TagBase):
class Meta:
verbose_name = "Fruit"
verbose_name_plural = "Fruits"
class TaggedFruit(GenericTaggedItemBase):
tag = models.ForeignKey(Fruit,
related_name="%(app_label)s_%(class)s_items")
class Box(models.Model):
name = models.CharField(max_length=199)
fruits = TaggableManager(through=TaggedFruit)
Then create basic model form:
class BoxModelForm(ModelForm):
class Meta:
model = Box
And that's it! You can now add fruit tags into your box, separated by comma. In case the fruit doesn't exist, it will be added into Fruit table. Read the docs for more details on how to use django-taggit.
You can use it together with jquery based Selectize.js.