Preserve foreign key ON DELETE attributes when FK columns are duplica…

…ted (#314)

Ensure that a foreign key's `ON DELETE` attribute is preserved when a
foreign key column is duplicated by a migration.

Fixes #313

pkg/migrations/duplicate.go

@@ -55,7 +55,7 @@ func (d *Duplicator) Duplicate(ctx context.Context) error {
 	const (
 		cAlterTableSQL         = `ALTER TABLE %s ADD COLUMN %s %s`
 		cSetDefaultSQL         = `ALTER COLUMN %s SET DEFAULT %s`
-		cAddForeignKeySQL      = `ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s)`
+		cAddForeignKeySQL      = `ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s) ON DELETE %s`
 		cAddCheckConstraintSQL = `ADD CONSTRAINT %s %s NOT VALID`
 		cCreateUniqueIndexSQL  = `CREATE UNIQUE INDEX CONCURRENTLY %s ON %s (%s)`
 	)
@@ -91,7 +91,9 @@ func (d *Duplicator) Duplicate(ctx context.Context) error {
 				pq.QuoteIdentifier(DuplicationName(fk.Name)),
 				strings.Join(quoteColumnNames(copyAndReplace(fk.Columns, d.column.Name, d.asName)), ", "),
 				pq.QuoteIdentifier(fk.ReferencedTable),
-				strings.Join(quoteColumnNames(fk.ReferencedColumns), ", "))
+				strings.Join(quoteColumnNames(fk.ReferencedColumns), ", "),
+				fk.OnDelete,
+			)
 		}
 	}
 

pkg/migrations/op_add_column_test.go

@@ -530,7 +530,7 @@ func TestAddForeignKeyColumn(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint exists on the new table.
-				ValidatedForeignKeyMustExist(t, db, schema, "orders", "fk_users_id")
+				ValidatedForeignKeyMustExist(t, db, schema, "orders", "fk_users_id", withOnDeleteCascade())
 
 				// Inserting a row into the referenced table succeeds.
 				MustInsert(t, db, schema, "01_create_table", "users", map[string]string{
@@ -563,7 +563,7 @@ func TestAddForeignKeyColumn(t *testing.T) {
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint still exists on the new table
-				ValidatedForeignKeyMustExist(t, db, schema, "orders", "fk_users_id")
+				ValidatedForeignKeyMustExist(t, db, schema, "orders", "fk_users_id", withOnDeleteCascade())
 
 				// Inserting a row into the referenced table succeeds.
 				MustInsert(t, db, schema, "02_add_column", "users", map[string]string{

pkg/migrations/op_change_type_test.go

@@ -190,9 +190,10 @@ func TestChangeColumnType(t *testing.T) {
 									Name: "department_id",
 									Type: "integer",
 									References: &migrations.ForeignKeyReference{
-										Name:   "fk_employee_department",
-										Table:  "departments",
-										Column: "id",
+										Name:     "fk_employee_department",
+										Table:    "departments",
+										Column:   "id",
+										OnDelete: migrations.ForeignKeyReferenceOnDeleteCASCADE,
 									},
 								},
 							},
@@ -214,13 +215,13 @@ func TestChangeColumnType(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// A temporary FK constraint has been created on the temporary column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"))
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"), withOnDeleteCascade())
 			},
 			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint still exists on the column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department")
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department", withOnDeleteCascade())
 			},
 		},
 		{

pkg/migrations/op_common_test.go

@@ -204,16 +204,16 @@ func UniqueConstraintMustExist(t *testing.T, db *sql.DB, schema, table, constrai
 	}
 }
 
-func ValidatedForeignKeyMustExist(t *testing.T, db *sql.DB, schema, table, constraint string) {
+func ValidatedForeignKeyMustExist(t *testing.T, db *sql.DB, schema, table, constraint string, opts ...foreignKeyOnDeleteOpt) {
 	t.Helper()
-	if !foreignKeyExists(t, db, schema, table, constraint, true) {
+	if !foreignKeyExists(t, db, schema, table, constraint, true, opts...) {
 		t.Fatalf("Expected validated foreign key %q to exist", constraint)
 	}
 }
 
-func NotValidatedForeignKeyMustExist(t *testing.T, db *sql.DB, schema, table, constraint string) {
+func NotValidatedForeignKeyMustExist(t *testing.T, db *sql.DB, schema, table, constraint string, opts ...foreignKeyOnDeleteOpt) {
 	t.Helper()
-	if !foreignKeyExists(t, db, schema, table, constraint, false) {
+	if !foreignKeyExists(t, db, schema, table, constraint, false, opts...) {
 		t.Fatalf("Expected not validated foreign key %q to exist", constraint)
 	}
 }
@@ -313,9 +313,24 @@ func uniqueConstraintExists(t *testing.T, db *sql.DB, schema, table, constraint
 	return exists
 }
 
-func foreignKeyExists(t *testing.T, db *sql.DB, schema, table, constraint string, validated bool) bool {
+type foreignKeyOnDeleteOpt func() string
+
+func withOnDeleteCascade() foreignKeyOnDeleteOpt {
+	return func() string { return "c" }
+}
+
+func withOnDeleteSetNull() foreignKeyOnDeleteOpt {
+	return func() string { return "n" }
+}
+
+func foreignKeyExists(t *testing.T, db *sql.DB, schema, table, constraint string, validated bool, opts ...foreignKeyOnDeleteOpt) bool {
 	t.Helper()
 
+	confDelType := "a"
+	for _, opt := range opts {
+		confDelType = opt()
+	}
+
 	var exists bool
 	err := db.QueryRow(`
     SELECT EXISTS (
@@ -325,8 +340,9 @@ func foreignKeyExists(t *testing.T, db *sql.DB, schema, table, constraint string
       AND conname = $2
       AND contype = 'f'
       AND convalidated = $3
+      AND confdeltype = $4 
     )`,
-		fmt.Sprintf("%s.%s", schema, table), constraint, validated).Scan(&exists)
+		fmt.Sprintf("%s.%s", schema, table), constraint, validated, confDelType).Scan(&exists)
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/migrations/op_create_table_test.go

@@ -237,7 +237,7 @@ func TestCreateTable(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint exists on the new table.
-				ValidatedForeignKeyMustExist(t, db, schema, migrations.TemporaryName("orders"), "fk_users_id")
+				ValidatedForeignKeyMustExist(t, db, schema, migrations.TemporaryName("orders"), "fk_users_id", withOnDeleteCascade())
 
 				// Inserting a row into the referenced table succeeds.
 				MustInsert(t, db, schema, "01_create_table", "users", map[string]string{
@@ -269,7 +269,7 @@ func TestCreateTable(t *testing.T) {
 				// The table has been dropped, so the foreign key constraint is gone.
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
-				ValidatedForeignKeyMustExist(t, db, schema, "orders", "fk_users_id")
+				ValidatedForeignKeyMustExist(t, db, schema, "orders", "fk_users_id", withOnDeleteCascade())
 
 				// Inserting a row into the referenced table succeeds.
 				MustInsert(t, db, schema, "02_create_table_with_fk", "users", map[string]string{

pkg/migrations/op_set_check_test.go

@@ -258,9 +258,10 @@ func TestSetCheckConstraint(t *testing.T) {
 									Type:     "integer",
 									Nullable: ptr(true),
 									References: &migrations.ForeignKeyReference{
-										Name:   "fk_employee_department",
-										Table:  "departments",
-										Column: "id",
+										Name:     "fk_employee_department",
+										Table:    "departments",
+										Column:   "id",
+										OnDelete: migrations.ForeignKeyReferenceOnDeleteCASCADE,
 									},
 								},
 							},
@@ -285,13 +286,13 @@ func TestSetCheckConstraint(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// A temporary FK constraint has been created on the temporary column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"))
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"), withOnDeleteCascade())
 			},
 			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint still exists on the column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department")
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department", withOnDeleteCascade())
 			},
 		},
 		{

pkg/migrations/op_set_fk_test.go

@@ -738,9 +738,10 @@ func TestSetForeignKey(t *testing.T) {
 							Table:  "posts",
 							Column: "user_id",
 							References: &migrations.ForeignKeyReference{
-								Name:   "fk_users_id_1",
-								Table:  "users",
-								Column: "id",
+								Name:     "fk_users_id_1",
+								Table:    "users",
+								Column:   "id",
+								OnDelete: migrations.ForeignKeyReferenceOnDeleteCASCADE,
 							},
 							Up:   ptr("(SELECT CASE WHEN EXISTS (SELECT 1 FROM users WHERE users.id = user_id) THEN user_id ELSE NULL END)"),
 							Down: ptr("user_id"),
@@ -766,13 +767,13 @@ func TestSetForeignKey(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// A temporary FK constraint has been created on the temporary column
-				ValidatedForeignKeyMustExist(t, db, schema, "posts", migrations.DuplicationName("fk_users_id_1"))
+				ValidatedForeignKeyMustExist(t, db, schema, "posts", migrations.DuplicationName("fk_users_id_1"), withOnDeleteCascade())
 			},
 			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint still exists on the column
-				ValidatedForeignKeyMustExist(t, db, schema, "posts", "fk_users_id_1")
+				ValidatedForeignKeyMustExist(t, db, schema, "posts", "fk_users_id_1", withOnDeleteCascade())
 			},
 		},
 		{

pkg/migrations/op_set_notnull_test.go

@@ -267,9 +267,10 @@ func TestSetNotNull(t *testing.T) {
 									Type:     "integer",
 									Nullable: ptr(true),
 									References: &migrations.ForeignKeyReference{
-										Name:   "fk_employee_department",
-										Table:  "departments",
-										Column: "id",
+										Name:     "fk_employee_department",
+										Table:    "departments",
+										Column:   "id",
+										OnDelete: migrations.ForeignKeyReferenceOnDeleteCASCADE,
 									},
 								},
 							},
@@ -291,13 +292,13 @@ func TestSetNotNull(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// A temporary FK constraint has been created on the temporary column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"))
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"), withOnDeleteCascade())
 			},
 			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint still exists on the column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department")
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department", withOnDeleteCascade())
 			},
 		},
 		{

pkg/migrations/op_set_unique_test.go

@@ -304,9 +304,10 @@ func TestSetColumnUnique(t *testing.T) {
 									Type:     "integer",
 									Nullable: ptr(true),
 									References: &migrations.ForeignKeyReference{
-										Name:   "fk_employee_department",
-										Table:  "departments",
-										Column: "id",
+										Name:     "fk_employee_department",
+										Table:    "departments",
+										Column:   "id",
+										OnDelete: migrations.ForeignKeyReferenceOnDeleteSETNULL,
 									},
 								},
 							},
@@ -330,13 +331,13 @@ func TestSetColumnUnique(t *testing.T) {
 			},
 			afterStart: func(t *testing.T, db *sql.DB, schema string) {
 				// A temporary FK constraint has been created on the temporary column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"))
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", migrations.DuplicationName("fk_employee_department"), withOnDeleteSetNull())
 			},
 			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
 			},
 			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
 				// The foreign key constraint still exists on the column
-				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department")
+				ValidatedForeignKeyMustExist(t, db, schema, "employees", "fk_employee_department", withOnDeleteSetNull())
 			},
 		},
 		{