Django Unleashed

7.3.9 Updating Objects with ModelForm

When we inherited ModelForm, we were able to remove our implementation of save(), because ModelForm provides its own. However, unlike our simple implementation, the ModelForm version of save() allows for objects to be created and updated.

The inheritance of ModelForm allows us to pass objects to the subclassed form via the instance attribute, as shown in Example 7.23.

Example 7.23: Python Interpreter Code

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>>> django_tag = Tag.objects.get(slug='django') >>> form = TagForm(instance=django_tag)

At the moment, if we run save(), nothing will happen because the data has not changed, and neither has the state of the form, as shown in Example 7.24.

Example 7.24: Python Interpreter ...