I have a legacy database, where some table contains composite primary key. The model I get by running manage.py inspectdb
command looks like this.
class MyTable(models.Model):
field1_id = models.IntegerField(db_column='field1id', primary_key=True)
is_favorite = models.BooleanField(db_column='isfavorite', default=False, null=False)
is_admin = models.BooleanField(db_column='isadmin', default=False, null=False)
role = models.IntegerField(default=USER_GUEST, null=False)
field2 = models.BooleanField(null=False, default=True)
field3 = models.BooleanField(null=False, default=True)
is_active = models.BooleanField(db_column='isactive', null=False, default=True)
user = models.ForeignKey(
CustomUser, models.DO_NOTHING, db_column='userid', primary_key=True)
class Meta:
managed = False
db_table = 'mytable'
unique_together = (('user', 'field1_id'),)
I can fetch data normally. However, the problem arises when I want to run save()
command on some model instance. The query django executes is not correct one. For example:
>>> from web_services.apps.my_app.models import MyTable
>>> g = MyTable.objects.get(field1_id=12)
>>> g.is_active = True
>>> g.save()
>>> connection.queries[-1]
{'time': '0.000', 'sql': 'UPDATE `mytable` SET `isfavorite` = 0, `isadmin` = 1, `role` = 3, `field2` = 1, `field3` = 1, `isactive` = 1 WHERE `mytable`.`field1id` = 12'}
But I need:
{'time': '0.000', 'sql': 'UPDATE `mytable` SET `isfavorite` = 0, `isadmin` = 1, `role` = 3, `field2` = 1, `field3` = 1, `isactive` = 1 WHERE `mytable`.`field1id` = 12' AND `mytable`.`userid` = 1'}
Since django does not support composite primary key, what would be the best solution to overcome that problem? Note, it's legacy database table and it didn't have AutoField
.
EDIT: adds legacy table structure
+------------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------+------+-----+---------+-------+
| userid | int(11) | NO | PRI | NULL | |
| field1id | int(11) | NO | PRI | NULL | |
| isfavorite | int(11) | NO | | 0 | |
| isadmin | int(11) | NO | | 0 | |
| role | int(11) | YES | | NULL | |
| field2 | tinyint(1) | NO | | 1 | |
| field3 | tinyint(1) | NO | | 1 | |
| isactive | tinyint(4) | NO | | 1 | |
+------------+------------+------+-----+---------+-------+
You must Delete managed = False command from the model to be able to edit your table
Unfortunately django does not yet have a composite primary key (composite primary keys are also called multi column primary keys)
There is a third party library, unsurprisingly name django-compositekey that makes it possible to create a model that has a multi column primary key. However that project is now maintained and not compatible with the latest versions of django.
Your best bet, is to add a new column into your table which is a an AutoField and make it the new primary key. The fields that make up the primary key at present can then be marked as unique_together. While this may not be ideally for a few queries. It's good enough for most.
If you update your question with the current table structure (as shown in your sql console) I will update my answer to show what the model will look like.
Update There are lots of different ways in which you can drop the old composite primary key and replace it with a new auto increment primary key. Here is the easiest, it involves just SQL
Then edit your model and remove the primary_key=True flag from those fields.
Footnote:
Some databases like sqlite for example does not support the
LIKE
clause in aCREATE TABLE
. In these cases, you will have to look up the create table statement for the original table, and copy paste after editing the table name. Judging by your table structure you seem to be using mysql and it supports theLIKE
clause.