diff options
Diffstat (limited to 'docs/ref/models')
| -rw-r--r-- | docs/ref/models/database-functions.txt | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/docs/ref/models/database-functions.txt b/docs/ref/models/database-functions.txt index acddc7cbe4..544c147ed2 100644 --- a/docs/ref/models/database-functions.txt +++ b/docs/ref/models/database-functions.txt @@ -88,8 +88,9 @@ Usage examples:: Accepts a list of at least two text fields or expressions and returns the concatenated text. Each argument must be of a text or char type. If you want to concatenate a ``TextField()`` with a ``CharField()``, then be sure to tell -Django that the ``output_field`` should be a ``TextField()``. This is also -required when concatenating a ``Value`` as in the example below. +Django that the ``output_field`` should be a ``TextField()``. Specifying an +``output_field`` is also required when concatenating a ``Value`` as in the +example below. This function will never have a null result. On backends where a null argument results in the entire expression being null, Django will ensure that each null @@ -102,8 +103,11 @@ Usage example:: >>> from django.db.models.functions import Concat >>> Author.objects.create(name='Margaret Smith', goes_by='Maggie') >>> author = Author.objects.annotate( - ... screen_name=Concat('name', V(' ('), 'goes_by', V(')'), - ... output_field=CharField())).get() + ... screen_name=Concat( + ... 'name', V(' ('), 'goes_by', V(')'), + ... output_field=CharField() + ... ) + ... ).get() >>> print(author.screen_name) Margaret Smith (Maggie) |