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| author | Mathieu Hinderyckx <mathieu@otainsight.com> | 2017-08-13 15:24:14 +0200 |
|---|---|---|
| committer | Tim Graham <timograham@gmail.com> | 2017-08-14 14:57:34 -0400 |
| commit | 1214e7c1b1248a7e51dfbdaaaed5bca56956f218 (patch) | |
| tree | 2df2c50812eb97c7d7b055d422084906c10f732f | |
| parent | b0ed14644a10dc8263e02b7f075e31169b450ea7 (diff) | |
[1.11.x] Clarified Concat example in docs.
Backport of cf5740fbc8414ab722b938f92b4363ff00d8db88 from master
| -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 a252069519..0b0b0050ff 100644 --- a/docs/ref/models/database-functions.txt +++ b/docs/ref/models/database-functions.txt @@ -90,8 +90,9 @@ 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 @@ -104,8 +105,11 @@ 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) |
