Correctly reference foreign key references when deferring (#12199)

.changes/unreleased/Fixes-20251124-170855.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: ':bug: :snowman: Correctly reference foreign key references when --defer and --state provided'
+time: 2025-11-24T17:08:55.387946-05:00
+custom:
+    Author: michellark
+    Issue: "11885"

core/dbt/compilation.py

@@ -654,8 +654,15 @@ class Compiler:
             raise GraphDependencyNotFoundError(node, to_expression)
 
         adapter = get_adapter(self.config)
-        relation_name = str(adapter.Relation.create_from(self.config, foreign_key_node))
-        return relation_name
+
+        if (
+            hasattr(foreign_key_node, "defer_relation")
+            and foreign_key_node.defer_relation
+            and self.config.args.defer
+        ):
+            return str(adapter.Relation.create_from(self.config, foreign_key_node.defer_relation))
+        else:
+            return str(adapter.Relation.create_from(self.config, foreign_key_node))
 
     # This method doesn't actually "compile" any of the nodes. That is done by the
     # "compile_node" method. This creates a Linker and builds the networkx graph,

tests/functional/constraints/fixtures.py

@@ -113,3 +113,10 @@ models:
           to: source('test_source', 'test_table')
           to_columns: [id]
 """
+
+
+stateful_generate_alias_name_macros_sql = """
+{% macro generate_alias_name(custom_alias_name, node) -%}
+    {{ node.name }}_{{ var("state", "dev") }}
+{%- endmacro %}
+"""

tests/functional/constraints/test_foreign_key_constraints.py

@@ -1,3 +1,6 @@
+import os
+import shutil
+
 import pytest
 
 from dbt.artifacts.resources import RefArgs
@@ -17,6 +20,7 @@ from tests.functional.constraints.fixtures import (
     model_foreign_key_model_node_not_found_schema_yml,
     model_foreign_key_model_schema_yml,
     model_foreign_key_source_schema_yml,
+    stateful_generate_alias_name_macros_sql,
 )
 
 
@@ -239,3 +243,57 @@ class TestColumnLevelForeignKeyConstraintRefSyntaxError:
             match="Invalid 'ref' or 'source' syntax on foreign key constraint 'to' on model my_model: invalid.",
         ):
             run_dbt(["parse"])
+
+
+class BaseForeignKeyDeferState:
+    @pytest.fixture(scope="class")
+    def macros(self):
+        return {
+            "generate_alias_name.sql": stateful_generate_alias_name_macros_sql,
+        }
+
+    def copy_state(self, project_root):
+        state_path = os.path.join(project_root, "state")
+        if not os.path.exists(state_path):
+            os.makedirs(state_path)
+        shutil.copyfile(
+            f"{project_root}/target/manifest.json", f"{project_root}/state/manifest.json"
+        )
+
+
+class TestModelLevelForeignKeyConstraintRefToDeferRelation(BaseForeignKeyDeferState):
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "constraints_schema.yml": model_foreign_key_model_schema_yml,
+            "my_model.sql": "select 1 as id",
+            "my_model_to.sql": "select 1 as id",
+        }
+
+    def test_model_level_fk_to_defer_relation(self, project):
+        results = run_dbt(["run", "--vars", "state: prod"])
+        self.copy_state(project.project_root)
+
+        results = run_dbt(["compile", "--defer", "--state", "state"])
+
+        my_model_node = [r.node for r in results.results if r.node.name == "my_model"][0]
+        assert my_model_node.constraints[0].to.split(".")[-1] == '"my_model_to_prod"'
+
+
+class TestColumnLevelForeignKeyConstraintToRefDeferRelation(BaseForeignKeyDeferState):
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "constraints_schema.yml": model_foreign_key_model_column_schema_yml,
+            "my_model.sql": "select 1 as id",
+            "my_model_to.sql": "select 1 as id",
+        }
+
+    def test_column_level_fk_to_defer_relation(self, project):
+        results = run_dbt(["run", "--vars", "state: prod"])
+        self.copy_state(project.project_root)
+
+        results = run_dbt(["compile", "--defer", "--state", "state"])
+
+        my_model_node = [r.node for r in results.results if r.node.name == "my_model"][0]
+        assert my_model_node.columns["id"].constraints[0].to.split(".")[-1] == '"my_model_to_prod"'