Saving ModelForm Data

Saving a ModelForm is like clicking one button that both checks your answers and files them straight into the database.

In this page:

Saving a New Instance
Updating an Existing Instance
Delaying the Save

Saving a New Instance

Calling save() on a valid, unbound-to-instance ModelForm creates a brand new database row.

Example: Saving a New Instance

Calling save() on a valid, unbound-to-instance ModelForm creates a brand new database row.

markup

form = ArticleForm(request.POST)
if form.is_valid():
    form.save()

{# Django-only code -- models.py/views.py/urls.py/settings.py snippets, or template markup using Django template tags/variables -- can't run standalone via Judge0 or the browser preview, since it needs a real Django project. Only this course's pure-Python examples (example_lang == 'python', no Django imports) are actually runnable, so those still get the button below. #}

Updating an Existing Instance

Passing instance=article binds the form to an existing row, so save() updates it instead of creating a new one.

Example: Updating an Existing Instance

Passing instance=article binds the form to an existing row, so save() updates it instead of creating a new one.

markup

form = ArticleForm(request.POST, instance=article)
if form.is_valid():
    form.save()

Delaying the Save

commit=False returns the model instance without writing to the database yet, letting you set extra fields first.

Example: Delaying the Save

commit=False returns the model instance without writing to the database yet, letting you set extra fields first.

markup

form = ArticleForm(request.POST)
if form.is_valid():
    article = form.save(commit=False)
    article.author = request.user
    article.save()

Common Mistakes

Calling form.save() without first checking form.is_valid(), which raises an error on invalid data.
Assuming form.save() always writes to the database, even when commit=False was passed.
Forgetting to set extra fields (like the logged-in user) on the instance before the final save() when using commit=False.

Chapter Summary

A valid ModelForm's save() method creates or updates a model instance and writes it to the database in one call.
Passing commit=False returns the unsaved instance so you can set extra fields before saving.
Always call is_valid() before save() — saving an invalid form raises an error.

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Saving ModelForm Data

Saving a New Instance

Updating an Existing Instance

Delaying the Save

Chapter Quiz — Complete all 11 topics to unlock

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