[1.8.x] Fixed #25326 -- Added namedtuple example for executing custom SQL.
Backport of 5ab65ca5c9
from master
This commit is contained in:
parent
800a162c0c
commit
5ed9616a09
|
@ -275,28 +275,50 @@ alias::
|
||||||
cursor = connections['my_db_alias'].cursor()
|
cursor = connections['my_db_alias'].cursor()
|
||||||
# Your code here...
|
# Your code here...
|
||||||
|
|
||||||
By default, the Python DB API will return results without their field
|
By default, the Python DB API will return results without their field names,
|
||||||
names, which means you end up with a ``list`` of values, rather than a
|
which means you end up with a ``list`` of values, rather than a ``dict``. At a
|
||||||
``dict``. At a small performance cost, you can return results as a
|
small performance and memory cost, you can return results as a ``dict`` by
|
||||||
``dict`` by using something like this::
|
using something like this::
|
||||||
|
|
||||||
def dictfetchall(cursor):
|
def dictfetchall(cursor):
|
||||||
"Returns all rows from a cursor as a dict"
|
"Return all rows from a cursor as a dict"
|
||||||
desc = cursor.description
|
desc = cursor.description
|
||||||
return [
|
return [
|
||||||
dict(zip([col[0] for col in desc], row))
|
dict(zip([col[0] for col in desc], row))
|
||||||
for row in cursor.fetchall()
|
for row in cursor.fetchall()
|
||||||
]
|
]
|
||||||
|
|
||||||
Here is an example of the difference between the two::
|
Another option is to use :func:`collections.namedtuple` from the Python
|
||||||
|
standard library. A ``namedtuple`` is a tuple-like object that has fields
|
||||||
|
accessible by attribute lookup; it's also indexable and iterable. Results are
|
||||||
|
immutable and accessible by field names or indices, which might be useful::
|
||||||
|
|
||||||
|
from collections import namedtuple
|
||||||
|
|
||||||
|
def namedtuplefetchall(cursor):
|
||||||
|
"Return all rows from a cursor as a namedtuple"
|
||||||
|
desc = cursor.description
|
||||||
|
nt_result = namedtuple('Result', [col[0] for col in desc])
|
||||||
|
return [nt_result(*row) for row in cursor.fetchall()]
|
||||||
|
|
||||||
|
Here is an example of the difference between the three::
|
||||||
|
|
||||||
>>> cursor.execute("SELECT id, parent_id FROM test LIMIT 2");
|
>>> cursor.execute("SELECT id, parent_id FROM test LIMIT 2");
|
||||||
>>> cursor.fetchall()
|
>>> cursor.fetchall()
|
||||||
((54360982L, None), (54360880L, None))
|
((54360982, None), (54360880, None))
|
||||||
|
|
||||||
>>> cursor.execute("SELECT id, parent_id FROM test LIMIT 2");
|
>>> cursor.execute("SELECT id, parent_id FROM test LIMIT 2");
|
||||||
>>> dictfetchall(cursor)
|
>>> dictfetchall(cursor)
|
||||||
[{'parent_id': None, 'id': 54360982L}, {'parent_id': None, 'id': 54360880L}]
|
[{'parent_id': None, 'id': 54360982}, {'parent_id': None, 'id': 54360880}]
|
||||||
|
|
||||||
|
>>> cursor.execute("SELECT id, parent_id FROM test LIMIT 2");
|
||||||
|
>>> results = namedtuplefetchall(cursor)
|
||||||
|
>>> results
|
||||||
|
[Result(id=54360982, parent_id=None), Result(id=54360880, parent_id=None)]
|
||||||
|
>>> results[0].id
|
||||||
|
54360982
|
||||||
|
>>> results[0][0]
|
||||||
|
54360982
|
||||||
|
|
||||||
Connections and cursors
|
Connections and cursors
|
||||||
-----------------------
|
-----------------------
|
||||||
|
|
Loading…
Reference in New Issue