ModelForm

ModelForm is a component of Django’s forms framework that automatically creates a form based on a Django model. It reduces boilerplate by generating form fields that correspond to model fields, keeping form logic in sync with the data model.

To use it, developers create a subclass of ModelForm and provide an inner Meta class that specifies the model and which fields to include or exclude. The form’s fields are derived from the model’s field definitions, and you can omit fields or customize which ones appear by listing them in fields or excluding them in exclude. If fields is omitted, all non-auto fields are included by default.

Validation in a ModelForm combines built-in model field validators with form-level validation. You can add custom validation by defining clean methods or a clean method for cross-field checks. When a bound form is valid, calling save() creates or updates the corresponding model instance. The save method accepts commit to control when the instance is actually saved to the database; you can pass commit=False to modify the instance before saving. You can also bind the form to an existing object via the instance parameter to update that object.

Customization and extensions include adjusting field labels, help_text, and widgets through the Meta options or the form itself, and adding non-model fields to the form if needed. ModelFormSet and inline formsets provide mechanisms for handling multiple related objects. In many Django applications, forms used for create and update operations are implemented as ModelForms, and the Django admin relies on ModelForm-based forms for editing models.