added composite primary key support

Author: NandanaRaol

mssql/features.py

@@ -3,8 +3,10 @@
 
 from django.db.backends.base.features import BaseDatabaseFeatures
 from django.utils.functional import cached_property
-
-
+from django import VERSION as django_version
+# Import CompositePrimaryKey only if Django version is 5.2 or higher
+if django_version >= (5, 2):    
+    from django.db.models.fields.composite import CompositePrimaryKey
 class DatabaseFeatures(BaseDatabaseFeatures):
     allows_group_by_select_index = False
     allow_sliced_subqueries_with_in = False
@@ -63,8 +65,11 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     supports_default_keyword_in_bulk_insert = True
     supports_stored_generated_columns = True
     supports_virtual_generated_columns = True
-
-
+    # CompositePrimaryKey support is only available in Django 5.2 and later
+    supports_composite_primary_keys = django_version >= (5, 2)
+    if django_version >= (5, 2) and isinstance(CompositePrimaryKey, type):
+       # Set fallback tupple lookup support
+       supports_tuple_lookups = False
     @cached_property
     def has_zoneinfo_database(self):
         with self.connection.cursor() as cursor:

mssql/schema.py

@@ -29,8 +29,9 @@
 if django_version >= (4, 0):
     from django.db.models.sql import Query
     from django.db.backends.ddl_references import Expressions
-
-
+# Import CompositePrimaryKey only if Django version is 5.2 or higher
+if django_version >= (5, 2):    
+    from django.db.models.fields.composite import CompositePrimaryKey
 class Statement(DjStatement):
     def __hash__(self):
         return hash((self.template, str(self.parts['name'])))
@@ -1315,7 +1316,19 @@ def create_model(self, model):
                 autoinc_sql = self.connection.ops.autoinc_sql(model._meta.db_table, field.column)
                 if autoinc_sql:
                     self.deferred_sql.extend(autoinc_sql)
-
+                   
+        # Initialize composite_pk_sql to None; will be set if composite primary key is detected
+        composite_pk_sql = None
+         # Check if Django version is >= 5.2 and the model has composite primary key fields
+        if django_version >= (5, 2) and hasattr(model._meta, "pk_fields"):
+          #specifically refers to the primary key field of that model.
+          pk = model._meta.pk
+          # Check if the primary key is a CompositePrimaryKey instance
+          if isinstance(pk, CompositePrimaryKey):
+              # Get the column names for all fields in the composite primary key
+             pk_columns = [field.column for field in model._meta.pk_fields]
+             # Build the PRIMARY KEY SQL clause for the composite key
+             composite_pk_sql = "PRIMARY KEY (%s)" % ", ".join(self.quote_name(col) for col in pk_columns)
         # Add any unique_togethers (always deferred, as some fields might be
         # created afterwards, like geometry fields with some backends)
         for field_names in model._meta.unique_together:
@@ -1328,6 +1341,9 @@ def create_model(self, model):
                 self.deferred_sql.append(self._create_unique_sql(model, columns, condition=condition))
 
         constraints = [constraint.constraint_sql(model, self) for constraint in model._meta.constraints]
+         # If a composite primary key SQL clause was generated, insert it at the beginning of the constraints list
+        if composite_pk_sql:
+          constraints.insert(0, composite_pk_sql)
         # Make the table
         sql = self.sql_create_table % {
             "table": self.quote_name(model._meta.db_table),