diff options
Diffstat (limited to 'docs/topics/db')
| -rw-r--r-- | docs/topics/db/models.txt | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/docs/topics/db/models.txt b/docs/topics/db/models.txt index a28e7e8805..1e69009827 100644 --- a/docs/topics/db/models.txt +++ b/docs/topics/db/models.txt @@ -707,6 +707,8 @@ below -- but there are a couple that you'll almost always want to define: Any object that has a URL that uniquely identifies it should define this method. +.. _overriding-model-methods: + Overriding predefined model methods ----------------------------------- @@ -726,9 +728,9 @@ to happen whenever you save an object. For example (see name = models.CharField(max_length=100) tagline = models.TextField() - def save(self, force_insert=False, force_update=False): + def save(self, *args, **kwargs): do_something() - super(Blog, self).save(force_insert, force_update) # Call the "real" save() method. + super(Blog, self).save(*args, **kwargs) # Call the "real" save() method. do_something_else() You can also prevent saving:: @@ -737,16 +739,24 @@ You can also prevent saving:: name = models.CharField(max_length=100) tagline = models.TextField() - def save(self, force_insert=False, force_update=False): + def save(self, *args, **kwargs): if self.name == "Yoko Ono's blog": return # Yoko shall never have her own blog! else: - super(Blog, self).save(force_insert, force_update) # Call the "real" save() method. + super(Blog, self).save(*args, **kwargs) # Call the "real" save() method. + +It's important to remember to call the superclass method -- that's +that ``super(Blog, self).save(*args, **kwargs)`` business -- to ensure +that the object still gets saved into the database. If you forget to +call the superclass method, the default behavior won't happen and the +database won't get touched. -It's important to remember to call the superclass method -- that's that -``super(Blog, self).save()`` business -- to ensure that the object still gets -saved into the database. If you forget to call the superclass method, the -default behavior won't happen and the database won't get touched. +It's also important that you pass through the arguments that can be +passed to the model method -- that's what the ``*args, **kwargs`` bit +does. Django will, from time to time, extend the capabilities of +built-in model methods, adding new arguments. If you use ``*args, +**kwargs`` in your method definitions, you are guaranteed that your +code will automatically support those arguments when they are added. Executing custom SQL -------------------- |