diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/ref/django-admin.txt | 19 | ||||
| -rw-r--r-- | docs/topics/db/multi-db.txt | 43 |
2 files changed, 35 insertions, 27 deletions
diff --git a/docs/ref/django-admin.txt b/docs/ref/django-admin.txt index 8ed489deb4..8a4a9bcc2b 100644 --- a/docs/ref/django-admin.txt +++ b/docs/ref/django-admin.txt @@ -423,25 +423,6 @@ define the fixture ``mydata.master.json`` or have specified that you want to load data onto the ``master`` database. -Excluding applications from loading -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -.. versionadded:: 1.2 - -The :djadminopt:`--exclude` option may be provided to prevent specific -applications from being loaded. - -For example, if you wanted to exclude models from ``django.contrib.auth`` -from being loaded into your database, you would call:: - - django-admin.py loaddata mydata.json --exclude auth - -This will look for for a JSON fixture called ``mydata`` in all the -usual locations - including the ``fixtures`` directory of the -``django.contrib.auth`` application. However, any fixture object that -identifies itself as belonging to the ``auth`` application (e.g., -instance of ``auth.User``) would be ignored by loaddata. - makemessages ------------ diff --git a/docs/topics/db/multi-db.txt b/docs/topics/db/multi-db.txt index dde63f61ee..2bd4c350c6 100644 --- a/docs/topics/db/multi-db.txt +++ b/docs/topics/db/multi-db.txt @@ -66,13 +66,9 @@ all databases in our example, you would need to call:: $ ./manage.py syncdb --database=users If you don't want every application to be synchronized onto a -particular database. you can specify the :djadminopt:`--exclude` -argument to :djadmin:`syncdb`. The :djadminopt:`--exclude` option lets -you prevent a specific application or applications from being -synchronized. For example, if you don't want the ``sales`` application -to be in the ``users`` database, you could run:: - - $ ./manage.py syncdb --database=users --exclude=sales +particular database, you can define a :ref:`database +router<topics-db-multi-db-routing>` that implements a policy +constraining the availability of particular models. Alternatively, if you want fine-grained control of synchronization, you can pipe all or part of the output of :djadmin:`sqlall` for a @@ -103,7 +99,7 @@ routing scheme. Database routers ---------------- -A database Router is a class that provides three methods: +A database Router is a class that provides four methods: .. method:: db_for_read(model, **hints) @@ -137,6 +133,14 @@ A database Router is a class that provides three methods: used by foreign key and many to many operations to determine if a relation should be allowed between two objects. +.. method:: allow_syncdb(db, model) + + Determine if the ``model`` should be synchronized onto the + database with alias ``db``. Return True if the model should be + synchronized, False if it should not be synchronized, or None if + the router has no opinion. This method can be used to determine + the availability of a model on a given database. + .. _topics-db-multi-db-hints: Hints @@ -221,6 +225,13 @@ master/slave relationship between the databases 'master', 'slave1' and return True return None + def allow_syncdb(self, db, model): + "Make sure the auth app only appears on the 'credentials' db" + if db == 'credentials': + return model._meta.app_label == 'auth' + elif model._meta.app_label == 'auth': + return False + return None class MasterSlaveRouter(object): """A router that sets up a simple master/slave configuration""" @@ -240,11 +251,26 @@ master/slave relationship between the databases 'master', 'slave1' and return True return None + def allow_syncdb(self, db, model): + "Explicitly put all models on all databases." + return True + Then, in your settings file, add the following (substituting ``path.to.`` with the actual python path to the module where you define the routers):: DATABASE_ROUTERS = ['path.to.AuthRouter', 'path.to.MasterSlaveRouter'] +The order in which routers are processed is significant. Routers will +be queried in the order the are listed in the +:setting:`DATABASE_ROUTERS` setting . In this example, the +``AuthRouter`` is processed before the ``MasterSlaveRouter``, and as a +result, decisions concerning the models in ``auth`` are processed +before any other decision is made. If the :setting:`DATABASE_ROUTERS` +setting listed the two routers in the other order, +``MasterSlaveRouter.allow_syncdb()`` would be processed first. The +catch-all nature of the MasterSlaveRouter implementation would mean +that all models would be available on all databases. + With this setup installed, lets run some Django code:: >>> # This retrieval will be performed on the 'credentials' database @@ -270,6 +296,7 @@ With this setup installed, lets run some Django code:: >>> # ... but if we re-retrieve the object, it will come back on a slave >>> mh = Book.objects.get(title='Mostly Harmless') + Manually selecting a database ============================= |