[1.11.x] Fixed #28161 -- Fixed return type of ArrayField(CITextField()).

Thanks Tim for the review.

Backport of b91868507af08234a30e9a8e7c90b37c561ba315 from master.

3 files changed, 24 insertions, 12 deletions

diff --git a/django/contrib/postgres/apps.py b/django/contrib/postgres/apps.py
index 0eeee6332b..9de733c261 100644
--- a/django/contrib/postgres/apps.py
+++ b/django/contrib/postgres/apps.py
@@ -5,7 +5,7 @@ from django.db.models import CharField, TextField
 from django.utils.translation import ugettext_lazy as _
 
 from .lookups import SearchLookup, TrigramSimilar, Unaccent
-from .signals import register_hstore_handler
+from .signals import register_type_handlers
 
 
 class PostgresConfig(AppConfig):
@@ -16,8 +16,8 @@ class PostgresConfig(AppConfig):
         # Connections may already exist before we are called.
         for conn in connections.all():
             if conn.connection is not None:
-                register_hstore_handler(conn)
-        connection_created.connect(register_hstore_handler)
+                register_type_handlers(conn)
+        connection_created.connect(register_type_handlers)
         CharField.register_lookup(Unaccent)
         TextField.register_lookup(Unaccent)
         CharField.register_lookup(SearchLookup)
diff --git a/django/contrib/postgres/operations.py b/django/contrib/postgres/operations.py
index cb45d4f705..cf790209b1 100644
--- a/django/contrib/postgres/operations.py
+++ b/django/contrib/postgres/operations.py
@@ -1,4 +1,4 @@
-from django.contrib.postgres.signals import register_hstore_handler
+from django.contrib.postgres.signals import register_type_handlers
 from django.db.migrations.operations.base import Operation
 
 
@@ -15,6 +15,10 @@ class CreateExtension(Operation):
         if schema_editor.connection.vendor != 'postgresql':
             return
         schema_editor.execute("CREATE EXTENSION IF NOT EXISTS %s" % schema_editor.quote_name(self.name))
+        # Registering new type handlers cannot be done before the extension is
+        # installed, otherwise a subsequent data migration would use the same
+        # connection.
+        register_type_handlers(schema_editor.connection)
 
     def database_backwards(self, app_label, schema_editor, from_state, to_state):
         schema_editor.execute("DROP EXTENSION %s" % schema_editor.quote_name(self.name))
@@ -40,13 +44,6 @@ class HStoreExtension(CreateExtension):
     def __init__(self):
         self.name = 'hstore'
 
-    def database_forwards(self, app_label, schema_editor, from_state, to_state):
-        super(HStoreExtension, self).database_forwards(app_label, schema_editor, from_state, to_state)
-        # Register hstore straight away as it cannot be done before the
-        # extension is installed, a subsequent data migration would use the
-        # same connection
-        register_hstore_handler(schema_editor.connection)
-
 
 class TrigramExtension(CreateExtension):
 
diff --git a/django/contrib/postgres/signals.py b/django/contrib/postgres/signals.py
index 183ba1d983..af7f0b2d30 100644
--- a/django/contrib/postgres/signals.py
+++ b/django/contrib/postgres/signals.py
@@ -1,10 +1,11 @@
+import psycopg2
 from psycopg2 import ProgrammingError
 from psycopg2.extras import register_hstore
 
 from django.utils import six
 
 
-def register_hstore_handler(connection, **kwargs):
+def register_type_handlers(connection, **kwargs):
     if connection.vendor != 'postgresql':
         return
 
@@ -23,3 +24,17 @@ def register_hstore_handler(connection, **kwargs):
         # This is also needed in order to create the connection in order to
         # install the hstore extension.
         pass
+
+    try:
+        with connection.cursor() as cursor:
+            # Retrieve oids of citext arrays.
+            cursor.execute("SELECT typarray FROM pg_type WHERE typname = 'citext'")
+            oids = tuple(row[0] for row in cursor)
+        array_type = psycopg2.extensions.new_array_type(oids, 'citext[]', psycopg2.STRING)
+        psycopg2.extensions.register_type(array_type, None)
+    except ProgrammingError:
+        # citext is not available on the database.
+        #
+        # The same comments in the except block of the above call to
+        # register_hstore() also apply here.
+        pass