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## Django documentation

# 13. Adding hooks before/after saving and deleting

Django provides hooks for executing arbitrary code around `save()` and `delete()`. Just add any of the following methods to your model:

> - `_pre_save()` is called before an object is saved.
> - `_post_save()` is called after an object is saved.
> - `_pre_delete()` is called before an object is deleted.
> - `_post_delete()` is called after an object is deleted.

## Model source code

    from django.core import meta

    class Person(meta.Model):
        first_name = meta.CharField(maxlength=20)
        last_name = meta.CharField(maxlength=20)

        def __repr__(self):
            return "%s %s" % (self.first_name, self.last_name)

        def _pre_save(self):
            print "Before save"

        def _post_save(self):
            print "After save"

        def _pre_delete(self):
            print "Before deletion"

        def _post_delete(self):
            print "After deletion"

## API reference

### Person objects have the following methods:

- `delete()`
- `save()`

## Sample API usage

This sample code assumes the above model has been saved in a file `examplemodel.py`.

    >>> from django.models.examplemodel import persons

    >>> p1 = persons.Person(first_name='John', last_name='Smith')
    >>> p1.save()
    Before save
    After save

    >>> persons.get_list()
    [John Smith]

    >>> p1.delete()
    Before deletion
    After deletion

    >>> persons.get_list()
    []

## Comments

### Simon Willison August 10, 2005 at 10:17 a.m.

Is it possible to prevent a save or delete from happening at all in the _pre_save and _pre_delete methods?

### Dustin August 23, 2005 at 3:39 p.m.

Is there a way to tell whether the object was added or updated from a _post_save?

It doesn't look like there's an obvious way from reading the source, but I would like to (for example) send an email whenever a particular record is created, but not when the record is updated.

### Clue September 6, 2005 at 1:42 a.m.

Dustin:
I'm not sure but you should check self.id value.
According to DB-API document, created new object will have id value of None.

### stava October 8, 2005 at 5:54 p.m.

The example here really should show how to reach the values of the object being saved (e.g. _pre_save()), rather than some useless print-statements.

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