#16055 closed Bug (fixed)
Filtering over generic relations with TextField/CharField object_id breaks in postgres
Reported by: | anonymous | Owned by: | David Wobrock |
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Component: | contrib.contenttypes | Version: | 3.2 |
Severity: | Normal | Keywords: | |
Cc: | victor.van.den.elzen@…, joeri@…, mmitar@…, brian@…, Kye Russell, Kevin Wiliarty, Marc DEBUREAUX, Sage Abdullah, David Wobrock | Triage Stage: | Ready for checkin |
Has patch: | yes | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
When you have a generic foreign key with TextField / CharField object_id, and try to use it in a filter with a model that has an integer primary key, PostgreSQL 9.0.4 errors out with this:
DatabaseError: operator does not exist: integer = text HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
A small example:
class Tag(models.Model): tag = models.SlugField() content_type = models.ForeignKey(ContentType) object_id = models.TextField() content_object = generic.GenericForeignKey() class Animal(models.Model): name = models.TextField() tags = generic.GenericRelation(Tag) print Animal.objects.filter(tags__tag='mammal')
I have a patch that changes Django's generic foreign key tests to also try everything with a textual object_id, which exhibits this problem.
A workaround is to create this cast as implicit in postgres:
CREATE CAST (integer AS text) WITH INOUT AS IMPLICIT
Attachments (3)
Change History (32)
by , 14 years ago
Attachment: | django_generic_text_id_test.diff added |
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comment:1 by , 14 years ago
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comment:2 by , 14 years ago
Cc: | added |
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comment:3 by , 14 years ago
Triage Stage: | Unreviewed → Accepted |
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Replying to anonymous:
When you have a generic foreign key with TextField / CharField object_id, and try to use it in a filter with a model that has an integer primary key, PostgreSQL 9.0.4 errors out with this:
DatabaseError: operator does not exist: integer = text HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.A small example:
I've verified this specific test case by modifying tests already present in the test suite (added in [12353]). See the attached patch.
I see no failure with Postgres 8.3 (the version in which cast behavior changes were introduced). Can you please test it with Postgres 9 and post the results?
comment:5 by , 9 years ago
Component: | Database layer (models, ORM) → contrib.contenttypes |
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Summary: | Filtering over funky generic relations breaks in postgres → Filtering over generic relations with TextField/CharField object_id breaks in postgres |
I updated the tests to apply cleanly to master and verified the failure on PostgreSQL 9.4 at 58c7ff39fb265754fb17ab8d7f8a1401b355777b (Django 1.10.dev).
====================================================================== ERROR: test_charlink_filter (generic_relations_regress.tests.GenericRelationTests) ---------------------------------------------------------------------- Traceback (most recent call last): File "/home/tim/code/django/tests/generic_relations_regress/tests.py", line 57, in test_charlink_filter list(OddRelation1.objects.filter(clinks__title='title')) File "/home/tim/code/django/django/db/models/query.py", line 258, in __iter__ self._fetch_all() File "/home/tim/code/django/django/db/models/query.py", line 1074, in _fetch_all self._result_cache = list(self.iterator()) File "/home/tim/code/django/django/db/models/query.py", line 52, in __iter__ results = compiler.execute_sql() File "/home/tim/code/django/django/db/models/sql/compiler.py", line 839, in execute_sql cursor.execute(sql, params) File "/home/tim/code/django/django/db/backends/utils.py", line 64, in execute return self.cursor.execute(sql, params) File "/home/tim/code/django/django/db/utils.py", line 92, in __exit__ six.reraise(dj_exc_type, dj_exc_value, traceback) File "/home/tim/code/django/django/db/backends/utils.py", line 64, in execute return self.cursor.execute(sql, params) ProgrammingError: operator does not exist: integer = character varying LINE 1: ...ON ("generic_relations_regress_oddrelation1"."id" = "generic... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
by , 9 years ago
Attachment: | 16055-test.diff added |
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comment:7 by , 9 years ago
Cc: | added |
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comment:8 by , 9 years ago
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comment:9 by , 7 years ago
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comment:10 by , 5 years ago
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comment:11 by , 5 years ago
If anyone is interested in addressing this issue it should be doable by adjusting Join.as_sql
to add the appropriate cast when lhs_col
and rhs_col
's .db_type(connection)
doesn't match.
Ideally most of the Cast
logic would be moved to the database backend operations so Join.as_sql
can rely on it instead of having to depend on db.models
stuff.
A less invasive solution would be to make GenericRelation
's join_field
return an empty get_joining_columns
and include the adapted condition in get_extra_restriction
instead but that seems like this should be solved at the Join
level instead since we don't offer a low level way of completely configuring join conditions; we only allow to augment them using FilteredRelation
.
comment:12 by , 5 years ago
I have made a hack for Django-guardian. In my case, this query is the one that fails:
from customers.models import CustomerMemberObjectPermission CustomerMemberObjectPermission.objects.filter(service_api__service__service_name='foo') # Raise DatabaseError
My models:
class CustomerMemberObjectPermission(UserObjectPermission): objects = CustomerMemberObjectPermissionManager() class ServiceApi(Model): customer_permissions = GenericRelation(CustomerMemberObjectPermission, object_id_field='object_pk', related_query_name='service_api')
This is the wrong sql:
SELECT "guardian_userobjectpermission"."id", "guardian_userobjectpermission"."permission_id", "guardian_userobjectpermission"."content_type_id", "guardian_userobjectpermission"."object_pk", "guardian_userobjectpermission"."user_id" FROM "guardian_userobjectpermission" INNER JOIN "services_serviceapi" ON ("guardian_userobjectpermission"."object_pk" = "services_serviceapi"."id" AND ("guardian_userobjectpermission"."content_type_id" = 22)) INNER JOIN "services_service" ON ("services_serviceapi"."service_id" = "services_service"."id") INNER JOIN "customers_customer" ON ("services_service"."customer_id" = "customers_customer"."id") WHERE "customers_customer"."customer_code" = BCL
The error is in the inner join. Django-guardian uses a field of type string for object_pk. But my id is a integer type:
"guardian_userobjectpermission"."object_pk" = "services_serviceapi"."id"
The solution is to use a cast:
CAST("guardian_userobjectpermission"."object_pk" AS integer) = "services_serviceapi"."id"
Although I know it is not the best, my solution has been this hack thanks to Simon Charette:
class CustomJoin(Join): def as_sql(self, compiler, connection): sql, params = super(CustomJoin, self).as_sql(compiler, connection) sql = sql.replace('"guardian_userobjectpermission"."object_pk"', 'CAST("guardian_userobjectpermission"."object_pk" AS integer)') return sql, params class CustomSQLCompiler(SQLCompiler): def compile(self, node, select_format=False): if isinstance(node, Join): node = CustomJoin( node.table_name, node.parent_alias, node.table_alias, node.join_type, node.join_field, node.nullable, node.filtered_relation ) return super(CustomSQLCompiler, self).compile(node, select_format) class CustomQuery(Query): def get_compiler(self, using=None, connection=None): original_compiler = super(CustomQuery, self).get_compiler(using=using, connection=connection) return CustomSQLCompiler(original_compiler.query, original_compiler.connection, original_compiler.using) # return super(CustomQuery, self).get_compiler(using=using, connection=connection) class CustomerMemberObjectPermissionQuerySet(CustomerQuerySet): def __init__(self, model=None, query=None, using=None, hints=None): if not query: query = CustomQuery(model) super(CustomerMemberObjectPermissionQuerySet, self).__init__( model=model, query=query, using=using, hints=hints ) class CustomerMemberObjectPermissionManager(CustomerManager, UserObjectPermissionManager): def get_queryset(self): return CustomerMemberObjectPermissionQuerySet(self.model, using=self._db)
comment:13 by , 4 years ago
Note that another elegant solution to this problem could be to add support to transforms to ForeignObject.to_fields
and .from_fields
so you could do something along these lines
class Animal(models.Model): name = models.TextField() tags = generic.GenericRelation(Tag, from_field='id__text')
(assuming we'd register a __text
lookup for IntegerField
)
comment:14 by , 4 years ago
Manage to create something based on Simon Charette's suggestion.
Creating a custom GenericRelation
with the following:
get_joining_columns
returning an empty tupleget_extra_restriction
building the whole where clause with content type AND primary key join with Cast
Here's the result:
class CustomGenericRelation(GenericRelation): def get_joining_columns(self, reverse_join=False): return () def get_extra_restriction(self, where_class, alias, remote_alias): cond = super().get_extra_restriction(where_class, alias, remote_alias) from_field = self.model._meta.pk to_field = self.remote_field.model._meta.get_field(self.object_id_field_name) lookup = from_field.get_lookup('exact')( Cast(from_field.get_col(alias), output_field=models.TextField()), to_field.get_col(remote_alias)) cond.add(lookup, 'AND') return cond
Giving the following:
- a model
common.History
having aGenericForeignKey
withobject_id
as text - a model
generic.Twitter
having aCustomGenericRelation
and a numeric primary key - and the queryset:
q = Twitter.objects.values('id').filter(id=1).annotate(count=Count('histories')) print(q.query)
It gives the following SQL query:
SELECT "generic_twitter"."id", COUNT("common_history"."id") AS "count" FROM "generic_twitter" LEFT OUTER JOIN "common_history" ON ((( "common_history"."content_type_id" = 29 AND CAST("generic_twitter"."id" AS text) = "common_history"."object_id" ))) WHERE "generic_twitter"."id" = 1 GROUP BY "generic_twitter"."id"
Instead of this one (normal behaviour):
SELECT "generic_twitter"."id", COUNT("common_history"."id") AS "count" FROM "generic_twitter" LEFT OUTER JOIN "common_history" ON ( "generic_twitter"."id" = "common_history"."object_id" AND ("common_history"."content_type_id" = 29) ) WHERE "generic_twitter"."id" = 1 GROUP BY "generic_twitter"."id"
comment:15 by , 4 years ago
Cc: | added |
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Version: | 1.3 → 3.2 |
Change Django version number for visibility purposes.
comment:16 by , 2 years ago
Cc: | added |
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comment:17 by , 21 months ago
Cc: | added |
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Has patch: | set |
Owner: | changed from | to
Status: | new → assigned |
comment:19 by , 21 months ago
Patch needs improvement: | unset |
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comment:20 by , 21 months ago
Patch needs improvement: | set |
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comment:21 by , 21 months ago
Patch needs improvement: | unset |
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comment:22 by , 21 months ago
Needs tests: | set |
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Patch needs improvement: | set |
comment:23 by , 20 months ago
Needs tests: | unset |
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Patch needs improvement: | unset |
comment:24 by , 20 months ago
Needs tests: | set |
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Patch needs improvement: | set |
comment:25 by , 19 months ago
Needs tests: | unset |
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Patch needs improvement: | unset |
comment:26 by , 19 months ago
Triage Stage: | Accepted → Ready for checkin |
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patch for tests