Fixed #32234 -- Made inspectdb inform about composite primary keys.

10 files changed, 88 insertions, 17 deletions

diff --git a/django/core/management/commands/inspectdb.py b/django/core/management/commands/inspectdb.py
index 43674dccf3..f33bcbdccf 100644
--- a/django/core/management/commands/inspectdb.py
+++ b/django/core/management/commands/inspectdb.py
@@ -106,11 +106,14 @@ class Command(BaseCommand):
                         )
                     except NotImplementedError:
                         constraints = {}
-                    primary_key_column = (
-                        connection.introspection.get_primary_key_column(
+                    primary_key_columns = (
+                        connection.introspection.get_primary_key_columns(
                             cursor, table_name
                         )
                     )
+                    primary_key_column = (
+                        primary_key_columns[0] if primary_key_columns else None
+                    )
                     unique_columns = [
                         c["columns"][0]
                         for c in constraints.values()
@@ -150,6 +153,12 @@ class Command(BaseCommand):
                     # Add primary_key and unique, if necessary.
                     if column_name == primary_key_column:
                         extra_params["primary_key"] = True
+                        if len(primary_key_columns) > 1:
+                            comment_notes.append(
+                                "The composite primary key (%s) found, that is not "
+                                "supported. The first column is selected."
+                                % ", ".join(primary_key_columns)
+                            )
                     elif column_name in unique_columns:
                         extra_params["unique"] = True
 
diff --git a/django/db/backends/base/features.py b/django/db/backends/base/features.py
index 68cad9fef2..c54d30cf73 100644
--- a/django/db/backends/base/features.py
+++ b/django/db/backends/base/features.py
@@ -260,6 +260,10 @@ class BaseDatabaseFeatures:
     create_test_procedure_without_params_sql = None
     create_test_procedure_with_int_param_sql = None
 
+    # SQL to create a table with a composite primary key for use by the Django
+    # test suite.
+    create_test_table_with_composite_primary_key = None
+
     # Does the backend support keyword parameters for cursor.callproc()?
     supports_callproc_kwargs = False
 
diff --git a/django/db/backends/base/introspection.py b/django/db/backends/base/introspection.py
index 8bf456225e..5e4acb3ff9 100644
--- a/django/db/backends/base/introspection.py
+++ b/django/db/backends/base/introspection.py
@@ -177,9 +177,14 @@ class BaseDatabaseIntrospection:
         """
         Return the name of the primary key column for the given table.
         """
+        columns = self.get_primary_key_columns(cursor, table_name)
+        return columns[0] if columns else None
+
+    def get_primary_key_columns(self, cursor, table_name):
+        """Return a list of primary key columns for the given table."""
         for constraint in self.get_constraints(cursor, table_name).values():
             if constraint["primary_key"]:
-                return constraint["columns"][0]
+                return constraint["columns"]
         return None
 
     def get_constraints(self, cursor, table_name):
diff --git a/django/db/backends/mysql/features.py b/django/db/backends/mysql/features.py
index 5387dffb9c..3ea3deeae3 100644
--- a/django/db/backends/mysql/features.py
+++ b/django/db/backends/mysql/features.py
@@ -39,6 +39,13 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             SET V_I = P_I;
         END;
     """
+    create_test_table_with_composite_primary_key = """
+        CREATE TABLE test_table_composite_pk (
+            column_1 INTEGER NOT NULL,
+            column_2 INTEGER NOT NULL,
+            PRIMARY KEY(column_1, column_2)
+        )
+    """
     # Neither MySQL nor MariaDB support partial indexes.
     supports_partial_indexes = False
     # COLLATE must be wrapped in parentheses because MySQL treats COLLATE as an
diff --git a/django/db/backends/oracle/features.py b/django/db/backends/oracle/features.py
index defd0a0ff8..289f786f5e 100644
--- a/django/db/backends/oracle/features.py
+++ b/django/db/backends/oracle/features.py
@@ -54,6 +54,13 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             V_I := P_I;
         END;
     """
+    create_test_table_with_composite_primary_key = """
+        CREATE TABLE test_table_composite_pk (
+            column_1 NUMBER(11) NOT NULL,
+            column_2 NUMBER(11) NOT NULL,
+            PRIMARY KEY (column_1, column_2)
+        )
+    """
     supports_callproc_kwargs = True
     supports_over_clause = True
     supports_frame_range_fixed_distance = True
diff --git a/django/db/backends/oracle/introspection.py b/django/db/backends/oracle/introspection.py
index 0fba9a21ed..ce743b291d 100644
--- a/django/db/backends/oracle/introspection.py
+++ b/django/db/backends/oracle/introspection.py
@@ -248,7 +248,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             for field_name, rel_table_name, rel_field_name in cursor.fetchall()
         }
 
-    def get_primary_key_column(self, cursor, table_name):
+    def get_primary_key_columns(self, cursor, table_name):
         cursor.execute(
             """
             SELECT
@@ -259,13 +259,13 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             WHERE
                 user_constraints.constraint_name = cols.constraint_name AND
                 user_constraints.constraint_type = 'P' AND
-                user_constraints.table_name = UPPER(%s) AND
-                cols.position = 1
+                user_constraints.table_name = UPPER(%s)
+            ORDER BY
+                cols.position
             """,
             [table_name],
         )
-        row = cursor.fetchone()
-        return self.identifier_converter(row[0]) if row else None
+        return [self.identifier_converter(row[0]) for row in cursor.fetchall()]
 
     def get_constraints(self, cursor, table_name):
         """
diff --git a/django/db/backends/postgresql/features.py b/django/db/backends/postgresql/features.py
index cbf499d785..0eed8c8d63 100644
--- a/django/db/backends/postgresql/features.py
+++ b/django/db/backends/postgresql/features.py
@@ -49,6 +49,13 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             V_I := P_I;
         END;
     $$ LANGUAGE plpgsql;"""
+    create_test_table_with_composite_primary_key = """
+        CREATE TABLE test_table_composite_pk (
+            column_1 INTEGER NOT NULL,
+            column_2 INTEGER NOT NULL,
+            PRIMARY KEY(column_1, column_2)
+        )
+    """
     requires_casted_case_in_updates = True
     supports_over_clause = True
     only_supports_unbounded_with_preceding_and_following = True
diff --git a/django/db/backends/sqlite3/features.py b/django/db/backends/sqlite3/features.py
index 2886ecc3be..6e10e61572 100644
--- a/django/db/backends/sqlite3/features.py
+++ b/django/db/backends/sqlite3/features.py
@@ -55,6 +55,13 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         # Date/DateTime fields and timedeltas.
         "expressions.tests.FTimeDeltaTests.test_mixed_comparisons1",
     }
+    create_test_table_with_composite_primary_key = """
+        CREATE TABLE test_table_composite_pk (
+            column_1 INTEGER NOT NULL,
+            column_2 INTEGER NOT NULL,
+            PRIMARY KEY(column_1, column_2)
+        )
+    """
 
     @cached_property
     def django_test_skips(self):
diff --git a/django/db/backends/sqlite3/introspection.py b/django/db/backends/sqlite3/introspection.py
index a74153757b..4805305aa5 100644
--- a/django/db/backends/sqlite3/introspection.py
+++ b/django/db/backends/sqlite3/introspection.py
@@ -156,15 +156,11 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             ) in cursor.fetchall()
         }
 
-    def get_primary_key_column(self, cursor, table_name):
-        """Return the column name of the primary key for the given table."""
+    def get_primary_key_columns(self, cursor, table_name):
         cursor.execute(
             "PRAGMA table_info(%s)" % self.connection.ops.quote_name(table_name)
         )
-        for _, name, *_, pk in cursor.fetchall():
-            if pk:
-                return name
-        return None
+        return [name for _, name, *_, pk in cursor.fetchall() if pk]
 
     def _parse_column_or_constraint_definition(self, tokens, columns):
         token = None
@@ -372,14 +368,14 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                 if orders is not None:
                     constraints[index]["orders"] = orders
         # Get the PK
-        pk_column = self.get_primary_key_column(cursor, table_name)
-        if pk_column:
+        pk_columns = self.get_primary_key_columns(cursor, table_name)
+        if pk_columns:
             # SQLite doesn't actually give a name to the PK constraint,
             # so we invent one. This is fine, as the SQLite backend never
             # deletes PK constraints by name, as you can't delete constraints
             # in SQLite; we remake the table with a new PK instead.
             constraints["__primary__"] = {
-                "columns": [pk_column],
+                "columns": pk_columns,
                 "primary_key": True,
                 "unique": False,  # It's not actually a unique constraint.
                 "foreign_key": None,
diff --git a/tests/inspectdb/tests.py b/tests/inspectdb/tests.py
index 39d5b6cbe5..76c5e2b940 100644
--- a/tests/inspectdb/tests.py
+++ b/tests/inspectdb/tests.py
@@ -585,3 +585,32 @@ class InspectDBTransactionalTests(TransactionTestCase):
                 )
                 cursor.execute("DROP SERVER IF EXISTS inspectdb_server")
                 cursor.execute("DROP EXTENSION IF EXISTS file_fdw")
+
+    @skipUnlessDBFeature("create_test_table_with_composite_primary_key")
+    def test_composite_primary_key(self):
+        table_name = "test_table_composite_pk"
+        with connection.cursor() as cursor:
+            cursor.execute(
+                connection.features.create_test_table_with_composite_primary_key
+            )
+        out = StringIO()
+        if connection.vendor == "sqlite":
+            field_type = connection.features.introspected_field_types["AutoField"]
+        else:
+            field_type = connection.features.introspected_field_types["IntegerField"]
+        try:
+            call_command("inspectdb", table_name, stdout=out)
+            output = out.getvalue()
+            self.assertIn(
+                f"column_1 = models.{field_type}(primary_key=True)  # The composite "
+                f"primary key (column_1, column_2) found, that is not supported. The "
+                f"first column is selected.",
+                output,
+            )
+            self.assertIn(
+                "column_2 = models.IntegerField()",
+                output,
+            )
+        finally:
+            with connection.cursor() as cursor:
+                cursor.execute("DROP TABLE %s" % table_name)