Django Foreign Fields is a Django app that offers two new form fields that help handling foreign relationships in a easier way.

bash pip install django-foreign-fields

Django-foreign-fields adds two new form fields ForeignField and TextAreaToManyField.

Both form fields need two new arguments: to and selector.

• to: the target model of the relationship. Declaring the target model as the first parameter will automatically be detected as the to argument.

• selector: the model field where the given value will be searched on.

Receives data and searches for an object in database that has that unique value on the given field. The object is stored as a ForeignKey.

Breaks all lines in a Textarea and use each one to find objects that correspond to each search. Each search must return a unique object, then, all objects are stored in a ManyToMany relationship.

Given you already have two models, one Target that holds some information and one Referrer that will make a foreign relationship to a particular field:

   class Target(models.Model):
      name = models.TextField()

   class Referrer(models.Model):
      foreign = models.ForeignKey()

It will be needed a new form for the Referrer.

The original form field that holds the foreign key relation on the Referrer will be substituted for the ForeignField:

   import foreign_fields.ForeignField

   class ReferrerForm(forms.ModelForm):
      foreign = foreign_fields.ForeignField(to=Target, selector='name')
      
      class Meta:
         model = Referrer

Now you can use the form on your View. The default widget is TextInput, so when you enter a string in the field and save the form, the ForeignField will search for a Target that has the given string in it's name field that must be unique. If the field is not unique, it will be given a ValidationError.

It's possible to change the foreign widget into others such as NumberInput or DateInput.

Given you already have two models, one Target that holds some information and one Referrer that will make a many to many relationship to a particular field:

   class Target(models.Model):
      name = models.TextField()

   class Referrer(models.Model):
      many_to_many = models.ManyToManyField()

It will be needed a new form for the Referrer.

The original form field that holds the many to many relation on the Referrer will be substituted for the TextAreaToManyField:

   import foreign_fields.TextAreaToManyField

   class ReferrerForm(forms.ModelForm):
      many_to_many = foreign_fields.TextAreaToManyField(to=Target, selector='name')
      
      class Meta:
           model = Referrer

Now you can use the form on your View. The default widget is Textarea, so when you enter a text in the field and save the form, the TextAreaToManyField will split each line and search for a unique Target by line that has the given string in it's name field. If the field is not unique, it will be given a ValidationError.