render to and to_columns on column and model level fk constraints

.changes/unreleased/Features-20240723-104221.yaml

@@ -0,0 +1,6 @@
+kind: Features
+body: render 'to' and 'to_columns' fields on foreign key constraints
+time: 2024-07-23T10:42:21.222203-04:00
+custom:
+  Author: michelleark
+  Issue: "271"

dbt-tests-adapter/dbt/tests/adapter/constraints/fixtures.py

@@ -363,7 +363,8 @@
           - type: check
             expression: id >= 1
           - type: foreign_key
-            expression: {schema}.foreign_key_model (id)
+            to: ref('foreign_key_model')
+            to_columns: ["id"]
           - type: unique
         data_tests:
           - unique

dbt/adapters/base/impl.py

@@ -1602,8 +1602,13 @@ def render_column_constraint(cls, constraint: ColumnLevelConstraint) -> Optional
             rendered_column_constraint = f"unique {constraint_expression}"
         elif constraint.type == ConstraintType.primary_key:
             rendered_column_constraint = f"primary key {constraint_expression}"
-        elif constraint.type == ConstraintType.foreign_key and constraint_expression:
-            rendered_column_constraint = f"references {constraint_expression}"
+        elif constraint.type == ConstraintType.foreign_key:
+            if constraint_expression:
+                rendered_column_constraint = f"references {constraint_expression}"
+            elif constraint.to and constraint.to_columns:
+                rendered_column_constraint = (
+                    f"references {constraint.to} ({', '.join(constraint.to_columns)})"
+                )
         elif constraint.type == ConstraintType.custom and constraint_expression:
             rendered_column_constraint = constraint_expression
 
@@ -1682,20 +1687,29 @@ def render_model_constraint(cls, constraint: ModelLevelConstraint) -> Optional[s
         rendering."""
         constraint_prefix = f"constraint {constraint.name} " if constraint.name else ""
         column_list = ", ".join(constraint.columns)
+        rendered_model_constraint = None
+
         if constraint.type == ConstraintType.check and constraint.expression:
-            return f"{constraint_prefix}check ({constraint.expression})"
+            rendered_model_constraint = f"{constraint_prefix}check ({constraint.expression})"
         elif constraint.type == ConstraintType.unique:
             constraint_expression = f" {constraint.expression}" if constraint.expression else ""
-            return f"{constraint_prefix}unique{constraint_expression} ({column_list})"
+            rendered_model_constraint = (
+                f"{constraint_prefix}unique{constraint_expression} ({column_list})"
+            )
         elif constraint.type == ConstraintType.primary_key:
             constraint_expression = f" {constraint.expression}" if constraint.expression else ""
-            return f"{constraint_prefix}primary key{constraint_expression} ({column_list})"
-        elif constraint.type == ConstraintType.foreign_key and constraint.expression:
-            return f"{constraint_prefix}foreign key ({column_list}) references {constraint.expression}"
+            rendered_model_constraint = (
+                f"{constraint_prefix}primary key{constraint_expression} ({column_list})"
+            )
+        elif constraint.type == ConstraintType.foreign_key:
+            if constraint.expression:
+                rendered_model_constraint = f"{constraint_prefix}foreign key ({column_list}) references {constraint.expression}"
+            elif constraint.to and constraint.to_columns:
+                rendered_model_constraint = f"{constraint_prefix}foreign key ({column_list}) references {constraint.to} ({', '.join(constraint.to_columns)})"
         elif constraint.type == ConstraintType.custom and constraint.expression:
-            return f"{constraint_prefix}{constraint.expression}"
-        else:
-            return None
+            rendered_model_constraint = f"{constraint_prefix}{constraint.expression}"
+
+        return rendered_model_constraint
 
     @classmethod
     def capabilities(cls) -> CapabilityDict:

tests/unit/test_base_adapter.py

@@ -39,6 +39,14 @@ def connection_manager(self):
             [{"type": "foreign_key", "expression": "other_table (c1)"}],
             ["column_name integer references other_table (c1)"],
         ),
+        (
+            [{"type": "foreign_key", "to": "other_table", "to_columns": ["c1"]}],
+            ["column_name integer references other_table (c1)"],
+        ),
+        (
+            [{"type": "foreign_key", "to": "other_table", "to_columns": ["c1", "c2"]}],
+            ["column_name integer references other_table (c1, c2)"],
+        ),
         ([{"type": "check"}, {"type": "unique"}], ["column_name integer unique"]),
         ([{"type": "custom", "expression": "-- noop"}], ["column_name integer -- noop"]),
     ]
@@ -176,6 +184,30 @@ def test_render_raw_columns_constraints_unsupported(
             ],
             ["constraint test_name foreign key (c1, c2) references other_table (c1)"],
         ),
+        (
+            [
+                {
+                    "type": "foreign_key",
+                    "columns": ["c1", "c2"],
+                    "to": "other_table",
+                    "to_columns": ["c1"],
+                    "name": "test_name",
+                }
+            ],
+            ["constraint test_name foreign key (c1, c2) references other_table (c1)"],
+        ),
+        (
+            [
+                {
+                    "type": "foreign_key",
+                    "columns": ["c1", "c2"],
+                    "to": "other_table",
+                    "to_columns": ["c1", "c2"],
+                    "name": "test_name",
+                }
+            ],
+            ["constraint test_name foreign key (c1, c2) references other_table (c1, c2)"],
+        ),
     ]
 
     @pytest.mark.parametrize("constraints,expected_rendered_constraints", model_constraints)