Fix startup errors in Django 3.1

.github/workflows/main.yml

@@ -41,11 +41,14 @@ jobs:
         tox_env:
           - "py36-django22"
           - "py36-django30"
+          - "py36-django31"
 
           - "py37-django22"
           - "py37-django30"
+          - "py37-django31"
 
           - "py38-django30"
+          - "py38-django31"
 
         include:
           - python: "3.6"
@@ -54,15 +57,24 @@ jobs:
           - python: "3.6"
             tox_env: "py36-django30"
 
+          - python: "3.6"
+            tox_env: "py36-django31"
+
           - python: "3.7"
             tox_env: "py37-django22"
 
           - python: "3.7"
             tox_env: "py37-django30"
 
+          - python: "3.7"
+            tox_env: "py37-django31"
+
           - python: "3.8"
             tox_env: "py38-django30"
 
+          - python: "3.8"
+            tox_env: "py38-django31"
+
 
     steps:
       - uses: actions/checkout@v2

.travis.yml

@@ -41,19 +41,25 @@ matrix:
 
     - { before_install: *linux_before_install, python: "3.6", os: linux, env: TOX_ENV=py36-django22 }
     - { before_install: *linux_before_install, python: "3.6", os: linux, env: TOX_ENV=py36-django30 }
+    - { before_install: *linux_before_install, python: "3.6", os: linux, env: TOX_ENV=py36-django31 }
 
     - { before_install: *linux_before_install, python: "3.7", os: linux, env: TOX_ENV=py37-django22 }
     - { before_install: *linux_before_install, python: "3.7", os: linux, env: TOX_ENV=py37-django30 }
+    - { before_install: *linux_before_install, python: "3.7", os: linux, env: TOX_ENV=py37-django31 }
 
     - { before_install: *linux_before_install, python: "3.8", os: linux, env: TOX_ENV=py38-django30 }
+    - { before_install: *linux_before_install, python: "3.8", os: linux, env: TOX_ENV=py38-django31 }
 
     - { before_install: *win_before_install, language: sh, python: "3.6", os: windows, env: TOX_ENV=py36-django22 }
     - { before_install: *win_before_install, language: sh, python: "3.6", os: windows, env: TOX_ENV=py36-django30 }
+    - { before_install: *win_before_install, language: sh, python: "3.6", os: windows, env: TOX_ENV=py36-django31 }
 
     - { before_install: *win_before_install, language: sh, python: "3.7", os: windows, env: TOX_ENV=py37-django22 }
     - { before_install: *win_before_install, language: sh, python: "3.7", os: windows, env: TOX_ENV=py37-django30 }
+    - { before_install: *win_before_install, language: sh, python: "3.7", os: windows, env: TOX_ENV=py37-django31 }
 
     - { before_install: *win_before_install, language: sh, python: "3.8", os: windows, env: TOX_ENV=py38-django30 }
+    - { before_install: *win_before_install, language: sh, python: "3.8", os: windows, env: TOX_ENV=py38-django31 }
 
 
 

sql_server/pyodbc/creation.py

@@ -1,10 +1,17 @@
 import binascii
 import os
 
+import django
 from django.db.backends.base.creation import BaseDatabaseCreation
 
 
 class DatabaseCreation(BaseDatabaseCreation):
+    @property
+    def cursor(self):
+        if django.VERSION >= (3, 1):
+            return self.connection._nodb_cursor
+
+        return self.connection._nodb_connection.cursor
 
     def _destroy_test_db(self, test_database_name, verbosity):
         """
@@ -14,7 +21,7 @@ def _destroy_test_db(self, test_database_name, verbosity):
         # ourselves. Connect to the previous database (not the test database)
         # to do so, because it's not allowed to delete a database while being
         # connected to it.
-        with self.connection._nodb_connection.cursor() as cursor:
+        with self.cursor() as cursor:
             to_azure_sql_db = self.connection.to_azure_sql_db
             if not to_azure_sql_db:
                 cursor.execute("ALTER DATABASE %s SET SINGLE_USER WITH ROLLBACK IMMEDIATE"
@@ -36,7 +43,7 @@ def enable_clr(self):
         This function will not fail if current user doesn't have
         permissions to enable clr, and clr is already enabled
         """
-        with self._nodb_connection.cursor() as cursor:
+        with self.cursor() as cursor:
             # check whether clr is enabled
             cursor.execute('''
             SELECT value FROM sys.configurations
@@ -86,7 +93,7 @@ def install_regex_clr(self, database_name):
 
         self.enable_clr()
 
-        with self._nodb_connection.cursor() as cursor:
+        with self.cursor() as cursor:
             for s in sql:
                 cursor.execute(s)
 

sql_server/pyodbc/features.py

@@ -22,6 +22,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     requires_literal_defaults = True
     requires_sqlparse_for_splitting = False
     supports_boolean_expr_in_select_clause = False
+    supports_deferrable_unique_constraints = False
     supports_ignore_conflicts = False
     supports_index_on_text_field = False
     supports_paramstyle_pyformat = False

sql_server/pyodbc/operations.py

@@ -1,9 +1,13 @@
 import datetime
 import uuid
 import warnings
+import django
 
 from django.conf import settings
 from django.db.backends.base.operations import BaseDatabaseOperations
+from django.db.models import Exists, ExpressionWrapper
+from django.db.models.expressions import RawSQL
+from django.db.models.sql.where import WhereNode
 from django.utils import timezone
 from django.utils.encoding import force_str
 
@@ -440,3 +444,18 @@ def time_trunc_sql(self, lookup_type, field_name):
         elif lookup_type == 'second':
             sql = "CONVERT(time, SUBSTRING(CONVERT(varchar, %s, 114), 0, 9))" % field_name
         return sql
+
+    def conditional_expression_supported_in_where_clause(self, expression):
+        """
+        Following "Moved conditional expression wrapping to the Exact lookup" in django 3.1
+        https://github.com/django/django/commit/37e6c5b79bd0529a3c85b8c478e4002fd33a2a1d
+        """
+        if django.VERSION >= (3, 1):
+            if isinstance(expression, (Exists, WhereNode)):
+                return True
+            if isinstance(expression, ExpressionWrapper) and expression.conditional:
+                return self.conditional_expression_supported_in_where_clause(expression.expression)
+            if isinstance(expression, RawSQL) and expression.conditional:
+                return True
+            return False
+        return True

sql_server/pyodbc/schema.py

@@ -694,13 +694,15 @@ def create_unique_name(*args, **kwargs):
                 name=name,
                 columns=columns,
                 condition=' WHERE ' + condition,
+                deferrable=''
             ) if self.connection.features.supports_partial_indexes else None
         else:
             return Statement(
                 self.sql_create_unique,
                 table=table,
                 name=name,
                 columns=columns,
+                deferrable=''
             )
 
     def _create_index_sql(self, model, fields, *, name=None, suffix='', using='',

tox.ini

@@ -2,6 +2,7 @@
 envlist =
        {py36,py37}-django22,
        {py36,py37,py38}-django30,
+       {py36,py37,py38}-django31,
 
 [testenv]
 passenv =
@@ -19,4 +20,5 @@ commands =
 deps =
     django22: django==2.2.*
     django30: django>=3.0a1,<3.1
+    django31: django>=3.1,<3.2
     dj-database-url==0.5.0