diff options
Diffstat (limited to 'docs/ref')
| -rw-r--r-- | docs/ref/contrib/postgres/fields.txt | 23 |
1 files changed, 7 insertions, 16 deletions
diff --git a/docs/ref/contrib/postgres/fields.txt b/docs/ref/contrib/postgres/fields.txt index 820f6de956..29dbc0db85 100644 --- a/docs/ref/contrib/postgres/fields.txt +++ b/docs/ref/contrib/postgres/fields.txt @@ -343,22 +343,6 @@ transform do not change. For example:: valid for a given field. This can be done using the :class:`~django.contrib.postgres.validators.KeysValidator`. -KeyTransform() expression -------------------------- - -.. class:: hstore.KeyTransform(key_name, *args, **kwargs) - -Returns the value of the given ``key_name``. This allows you to annotate a key -value. For example:: - - >>> from django.contrib.postgres.fields.hstore import KeyTransform - >>> Dog.objects.create(name="Rufus", data={"breed": "labrador"}) - >>> Dog.objects.create(name="Meg", data={"breed": "collie", "owner": "Bob"}) - - >>> rufus = Dog.objects.annotate(breed=KeyTransform("breed", "data"))[0] - >>> rufus.breed - 'labrador' - Querying ``HStoreField`` ------------------------ @@ -395,6 +379,13 @@ You can chain other lookups after key lookups:: >>> Dog.objects.filter(data__breed__contains='l') <QuerySet [<Dog: Rufus>, <Dog: Meg>]> +or use ``F()`` expressions to annotate a key value. For example:: + + >>> from django.db.models import F + >>> rufus = Dog.objects.annotate(breed=F("data__breed"))[0] + >>> rufus.breed + 'labrador' + If the key you wish to query by clashes with the name of another lookup, you need to use the :lookup:`hstorefield.contains` lookup instead. |