Add basic support for JSONField

Initial support for Json, does not have lookups like `contains` and `has` yet.

Author: absci

.gitignore

@@ -6,7 +6,7 @@
 Thumbs.db
 
 *.egg-info
-
+*.dll
 tests/local_settings.py
 
 # Virtual Env

mssql/base.py

@@ -88,6 +88,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         'IntegerField': 'int',
         'IPAddressField': 'nvarchar(15)',
         'GenericIPAddressField': 'nvarchar(39)',
+        'JSONField': 'nvarchar(max)',
         'NullBooleanField': 'bit',
         'OneToOneField': 'int',
         'PositiveIntegerField': 'int',

mssql/compiler.py

@@ -13,7 +13,7 @@
 from django.db.models.sql import compiler
 from django.db.transaction import TransactionManagementError
 from django.db.utils import NotSupportedError
-
+from django.db.models.fields.json import compile_json_path, KeyTransform as json_KeyTransform
 
 def _as_sql_agv(self, compiler, connection):
     return self.as_sql(compiler, connection, template='%(function)s(CONVERT(float, %(field)s))')
@@ -42,6 +42,11 @@ def _as_sql_greatest(self, compiler, connection):
     template = '(SELECT MAX(value) FROM (VALUES (%(expressions)s)) AS _%(function)s(value))'
     return self.as_sql(compiler, connection, arg_joiner='), (', template=template)
 
+def _as_sql_json_keytransform(self, compiler, connection):
+    lhs, params, key_transforms = self.preprocess_lhs(compiler, connection)
+    json_path = compile_json_path(key_transforms)
+
+    return 'JSON_VALUE(%s, %%s)' % lhs, tuple(params) + (json_path,)
 
 def _as_sql_least(self, compiler, connection):
     # SQL Server does not provide LEAST function,
@@ -382,6 +387,8 @@ def _as_microsoft(self, node):
             as_microsoft = _as_sql_count
         elif isinstance(node, Greatest):
             as_microsoft = _as_sql_greatest
+        if isinstance(node, json_KeyTransform):
+            as_microsoft = _as_sql_json_keytransform
         elif isinstance(node, Least):
             as_microsoft = _as_sql_least
         elif isinstance(node, Length):

mssql/features.py

@@ -6,31 +6,35 @@
 
 
 class DatabaseFeatures(BaseDatabaseFeatures):
-    has_native_uuid_field = False
     allow_sliced_subqueries_with_in = False
     can_introspect_autofield = True
+    can_introspect_json_field = False
     can_introspect_small_integer_field = True
     can_return_columns_from_insert = True
     can_return_id_from_insert = True
     can_use_chunked_reads = False
     for_update_after_from = True
     greatest_least_ignores_nulls = True
+    has_json_operators = False
+    has_native_json_field = False
+    has_native_uuid_field = False
     has_real_datatype = True
     has_select_for_update = True
     has_select_for_update_nowait = True
     has_select_for_update_skip_locked = True
-    ignores_table_name_case = True
     ignores_quoted_identifier_case = True
+    ignores_table_name_case = True
     order_by_nulls_first = True
     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_json_field = False
+    supports_json_field_contains = False
     supports_order_by_nulls_modifier = False
     supports_paramstyle_pyformat = False
+    supports_primitives_in_json_field = False
     supports_regex_backreferencing = True
     supports_sequence_reset = False
     supports_subqueries_in_group_by = False
@@ -65,3 +69,7 @@ def has_zoneinfo_database(self):
         with self.connection.cursor() as cursor:
             cursor.execute("SELECT TOP 1 1 FROM sys.time_zone_info")
             return cursor.fetchone() is not None
+
+    @cached_property
+    def supports_json_field(self):
+        return self.connection.sql_server_version >= 2016

mssql/functions.py

@@ -6,7 +6,8 @@
 from django.db.models.functions import Cast
 from django.db.models.functions.math import ATan2, Log, Ln, Mod, Round
 from django.db.models.expressions import Case, Exists, OrderBy, When
-from django.db.models.lookups import Lookup, In
+from django.db.models.lookups import Lookup, In, Exact
+from django.db.models.fields.json import KeyTransform, KeyTransformExact
 
 DJANGO3 = VERSION[0] >= 3
 
@@ -108,12 +109,22 @@ def split_parameter_list_as_sql(self, compiler, connection):
 
     return in_clause, ()
 
+def KeyTransformExact_process_rhs(self, compiler, connection):
+    if isinstance(self.rhs, KeyTransform):
+        return super(Exact, self).process_rhs(compiler, connection)
+    rhs, rhs_params = super(Exact, self).process_rhs(compiler, connection)
+    if connection.vendor == 'microsoft':
+        if rhs_params != [None]:
+            rhs_params = [params.strip('"') for params in rhs_params]
+    return rhs, rhs_params
+
 ATan2.as_microsoft = sqlserver_atan2
-Log.as_microsoft = sqlserver_log
+In.split_parameter_list_as_sql = split_parameter_list_as_sql
+KeyTransformExact.process_rhs = KeyTransformExact_process_rhs
 Ln.as_microsoft = sqlserver_ln
+Log.as_microsoft = sqlserver_log
 Mod.as_microsoft = sqlserver_mod
 Round.as_microsoft = sqlserver_round
-In.split_parameter_list_as_sql = split_parameter_list_as_sql
 
 if DJANGO3:
     Lookup.as_microsoft = sqlserver_lookup

setup.py

@@ -36,6 +36,7 @@
     install_requires=[
         'pyodbc>=3.0',
     ],
+    package_data={'mssql': ['regex_clr.dll']},
     classifiers=CLASSIFIERS,
     keywords='django',
 )

testapp/settings.py

@@ -186,7 +186,33 @@
                   'queries.test_db_returning.ReturningValuesTests.test_insert_returning_multiple',
                   'dbshell.tests.DbshellCommandTestCase.test_command_missing',
                   'schema.tests.SchemaTests.test_char_field_pk_to_auto_field',
-                  'datetimes.tests.DateTimesTests.test_21432'
+                  'datetimes.tests.DateTimesTests.test_21432',
+
+                  #JSONFields
+                  'model_fields.test_jsonfield.TestQuerying.test_has_any_keys',
+                  'model_fields.test_jsonfield.TestQuerying.test_has_key',
+                  'model_fields.test_jsonfield.TestQuerying.test_has_key_deep',
+                  'model_fields.test_jsonfield.TestQuerying.test_has_key_list',
+                  'model_fields.test_jsonfield.TestQuerying.test_has_key_null_value',
+                  'model_fields.test_jsonfield.TestQuerying.test_has_keys',
+                  'model_fields.test_jsonfield.TestQuerying.test_key_iregex',
+                  'model_fields.test_jsonfield.TestQuerying.test_key_quoted_string',
+                  'model_fields.test_jsonfield.TestQuerying.test_key_regex',
+                  'model_fields.test_jsonfield.TestQuerying.test_lookups_with_key_transform',
+                  'model_fields.test_jsonfield.TestQuerying.test_order_grouping_custom_decoder',
+                  'model_fields.test_jsonfield.TestQuerying.test_ordering_grouping_by_count',
+                  'model_fields.test_jsonfield.TestQuerying.test_ordering_grouping_by_key_transform',
+                  'model_fields.test_jsonfield.JSONFieldTests.test_db_check_constraints',
+                  'model_fields.test_jsonfield.TestQuerying.test_isnull_key',
+                  'model_fields.test_jsonfield.TestQuerying.test_key_in',
+                  'model_fields.test_jsonfield.TestQuerying.test_key_transform_expression',
+                  'model_fields.test_jsonfield.TestQuerying.test_key_values',
+                  'model_fields.test_jsonfield.TestQuerying.test_nested_key_transform_expression',
+                  'model_fields.test_jsonfield.TestQuerying.test_none_key',
+                  'model_fields.test_jsonfield.TestQuerying.test_none_key_and_exact_lookup',
+                  'model_fields.test_jsonfield.TestQuerying.test_none_key_exclude',
+                  'model_fields.test_jsonfield.TestQuerying.test_ordering_by_transform',
+                  'model_fields.test_jsonfield.TestQuerying.test_shallow_lookup_obj_target'
                   ]
 
 REGEX_TESTS = ['lookup.tests.LookupTests.test_regex',