sql/dialect/schema: ignore foreign-keys in index dropping

Summary: Pull Request resolved: https://github.com/facebookincubator/ent/pull/188

Reviewed By: alexsn

Differential Revision: D18676877

fbshipit-source-id: 0babe457edadfa46dcbc7c7478d4468c48f84361

dialect/sql/schema/migrate.go

@@ -109,7 +109,7 @@ func (m *Migrate) Create(ctx context.Context, tables ...*Table) error {
 
 func (m *Migrate) create(ctx context.Context, tx dialect.Tx, tables ...*Table) error {
 	for _, t := range tables {
-		t.setup()
+		m.setupTable(t)
 		switch exist, err := m.tableExist(ctx, tx, t.Name); {
 		case err != nil:
 			return err
@@ -154,7 +154,6 @@ func (m *Migrate) create(ctx context.Context, tx dialect.Tx, tables ...*Table) e
 		}
 		fks := make([]*ForeignKey, 0, len(t.ForeignKeys))
 		for _, fk := range t.ForeignKeys {
-			fk.Symbol = m.symbol(fk.Symbol)
 			exist, err := m.fkExist(ctx, tx, fk.Symbol)
 			if err != nil {
 				return err
@@ -310,7 +309,9 @@ func (m *Migrate) changeSet(curr, new *Table) (*changes, error) {
 
 	// drop indexes.
 	for _, idx1 := range curr.Indexes {
-		if _, ok := new.index(idx1.Name); !ok {
+		_, ok1 := new.fk(idx1.Name)
+		_, ok2 := new.index(idx1.Name)
+		if !ok1 && !ok2 {
 			change.index.drop.append(idx1)
 		}
 	}
@@ -370,6 +371,30 @@ func (m *Migrate) allocPKRange(ctx context.Context, tx dialect.Tx, t *Table) err
 	return m.setRange(ctx, tx, t.Name, id<<32)
 }
 
+// setup ensures the table is configured properly, like table columns
+// are linked to their indexes, and PKs columns are defined.
+func (m *Migrate) setupTable(t *Table) {
+	if t.columns == nil {
+		t.columns = make(map[string]*Column, len(t.Columns))
+	}
+	for _, c := range t.Columns {
+		t.columns[c.Name] = c
+	}
+	for _, idx := range t.Indexes {
+		for _, c := range idx.Columns {
+			c.indexes.append(idx)
+		}
+	}
+	for _, pk := range t.PrimaryKey {
+		c := t.columns[pk.Name]
+		c.Key = PrimaryKey
+		pk.Key = PrimaryKey
+	}
+	for _, fk := range t.ForeignKeys {
+		fk.Symbol = m.symbol(fk.Symbol)
+	}
+}
+
 // symbol makes sure the symbol length is not longer than the maxlength in the dialect.
 func (m *Migrate) symbol(name string) string {
 	size := 64

dialect/sql/schema/mysql_test.go

@@ -708,6 +708,56 @@ func TestMySQL_Create(t *testing.T) {
 				mock.ExpectCommit()
 			},
 		},
+		{
+			name: "ignore foreign keys on index dropping",
+			tables: []*Table{
+				{
+					Name: "users",
+					Columns: []*Column{
+						{Name: "id", Type: field.TypeInt, Increment: true},
+						{Name: "parent_id", Type: field.TypeInt, Nullable: true},
+					},
+					PrimaryKey: []*Column{
+						{Name: "id", Type: field.TypeInt, Increment: true},
+					},
+					ForeignKeys: []*ForeignKey{
+						{
+							Symbol: "parent_id",
+							Columns: []*Column{
+								{Name: "parent_id", Type: field.TypeInt, Nullable: true},
+							},
+						},
+					},
+				},
+			},
+			options: []MigrateOption{WithDropIndex(true)},
+			before: func(mock sqlmock.Sqlmock) {
+				mock.ExpectBegin()
+				mock.ExpectQuery(escape("SHOW VARIABLES LIKE 'version'")).
+					WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).AddRow("version", "5.7.23"))
+				mock.ExpectQuery(escape("SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
+					WithArgs("users").
+					WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+				mock.ExpectQuery(escape("SELECT `column_name`, `column_type`, `is_nullable`, `column_key`, `column_default`, `extra`, `character_set_name`, `collation_name` FROM INFORMATION_SCHEMA.COLUMNS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
+					WithArgs("users").
+					WillReturnRows(sqlmock.NewRows([]string{"column_name", "column_type", "is_nullable", "column_key", "column_default", "extra", "character_set_name", "collation_name"}).
+						AddRow("id", "bigint(20)", "NO", "PRI", "NULL", "auto_increment", "", "").
+						AddRow("parent_id", "bigint(20)", "YES", "NULL", "NULL", "", "", ""))
+				mock.ExpectQuery(escape("SELECT `index_name`, `column_name`, `non_unique`, `seq_in_index` FROM INFORMATION_SCHEMA.STATISTICS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
+					WithArgs("users").
+					WillReturnRows(sqlmock.NewRows([]string{"index_name", "column_name", "non_unique", "seq_in_index"}).
+						AddRow("PRIMARY", "id", "0", "1").
+						AddRow("old_index", "old", "0", "1").
+						AddRow("parent_id", "parent_id", "0", "1"))
+				// drop the unique index.
+				mock.ExpectExec(escape("DROP INDEX `old_index` ON `users`")).
+					WillReturnResult(sqlmock.NewResult(0, 1))
+				// foreign key already exist.
+				mock.ExpectQuery(escape("SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `CONSTRAINT_TYPE` = ? AND `CONSTRAINT_NAME` = ?")).
+					WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+				mock.ExpectCommit()
+			},
+		},
 		{
 			name: "add edge to table",
 			tables: func() []*Table {

dialect/sql/schema/schema.go

@@ -82,27 +82,6 @@ func (t *Table) AddIndex(name string, unique bool, columns []string) *Table {
 	return t
 }
 
-// setup ensures the table is configured properly, like table columns
-// are linked to their indexes, and PKs columns are defined.
-func (t *Table) setup() {
-	if t.columns == nil {
-		t.columns = make(map[string]*Column, len(t.Columns))
-	}
-	for _, c := range t.Columns {
-		t.columns[c.Name] = c
-	}
-	for _, idx := range t.Indexes {
-		for _, c := range idx.Columns {
-			c.indexes.append(idx)
-		}
-	}
-	for _, pk := range t.PrimaryKey {
-		c := t.columns[pk.Name]
-		c.Key = PrimaryKey
-		pk.Key = PrimaryKey
-	}
-}
-
 // column returns a table column by its name.
 // faster than map lookup for most cases.
 func (t *Table) column(name string) (*Column, bool) {
@@ -135,6 +114,17 @@ func (t *Table) index(name string) (*Index, bool) {
 	return nil, false
 }
 
+// fk returns a table foreign-key by its symbol.
+// faster than map lookup for most cases.
+func (t *Table) fk(symbol string) (*ForeignKey, bool) {
+	for _, fk := range t.ForeignKeys {
+		if fk.Symbol == symbol {
+			return fk, true
+		}
+	}
+	return nil, false
+}
+
 // Column schema definition for SQL dialects.
 type Column struct {
 	Name      string      // column name.