Enable SQL Window functions for use in Django queries. Add rank to your query.
MIT License
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Warning: Since Django 2.0 this application is deprecated. Use built in window functions <https://docs.djangoproject.com/en/2.0/ref/models/database-functions/#window-functions>
_.
Enable SQL Window functions for use in Django queries. Add rank to your query.
Django in curren't version (1.10) doesn't support window functions <https://www.postgresql.org/docs/9.3/static/functions-window.html>
_ as seen in PostgreSQL.
This implemets rank
, dense_rank
and adds shortcut for upper_rank
, which retrieves upper value for rank (rank of last element in the window).
The implementation is currently working only on PostgreSQL.
Note: The support for window functions is being already solved in issue #26608 <https://code.djangoproject.com/ticket/26608>
_.
Install rank::
pip install django-rank-query
U can annotate users by rank (sequenc number in alphabet) of their last name the like this::
from rank import DenseRank, UpperRank, Rank
users = User.objects.all()
users = user.annotate(lower_rank=Rank('last_name'))
users = user.annotate(upper_rank=UpperRank('last_name'))
users = user.annotate(dense_rank=DenseRank('last_name'))
Then you have user query annotated with various ranks. You can retrieve them for example by values
function::
user_ranks = users.values('last_name', 'lower_rank', 'upper_rank')
Note: PostgreSQL doesn't support combining rank
functions with GROUP_BY
or in WHERE
clause. So you cannot use them in aggregation queries.
Rank is counted in the current select
query, so filtering will change rank of given elements, so you can't have sequence number in whole table filtered by ie. his name.
This can be solved by using subqueries in SQL, but Django doesn't support them as far as I know.
Does the code actually work?
::
source <YOURVIRTUALENV>/bin/activate
(myenv) $ pip install tox
(myenv) $ tox
Tools used in rendering this package:
cookiecutter-djangopackage
_.. _Cookiecutter: https://github.com/audreyr/cookiecutter
.. _cookiecutter-djangopackage
: https://github.com/pydanny/cookiecutter-djangopackage