New DBAction: DropConstraintAction (#849)

Related to #742

Author: kvch

pkg/migrations/dbactions.go

@@ -535,3 +535,24 @@ func getSequenceNameForColumn(ctx context.Context, conn db.DB, tableName, column
 
 	return sequenceName
 }
+
+type dropConstraintAction struct {
+	conn       db.DB
+	table      string
+	constraint string
+}
+
+func NewDropConstraintAction(conn db.DB, table, constraint string) *dropConstraintAction {
+	return &dropConstraintAction{
+		conn:       conn,
+		table:      table,
+		constraint: constraint,
+	}
+}
+
+func (a *dropConstraintAction) Execute(ctx context.Context) error {
+	_, err := a.conn.ExecContext(ctx, fmt.Sprintf("ALTER TABLE IF EXISTS %s DROP CONSTRAINT IF EXISTS %s",
+		pq.QuoteIdentifier(a.table),
+		pq.QuoteIdentifier(a.constraint)))
+	return err
+}

pkg/migrations/op_add_column.go

@@ -358,9 +358,7 @@ func upgradeNotNullConstraintToNotNullAttribute(ctx context.Context, conn db.DB,
 		return err
 	}
 
-	_, err = conn.ExecContext(ctx, fmt.Sprintf("ALTER TABLE IF EXISTS %s DROP CONSTRAINT IF EXISTS %s",
-		pq.QuoteIdentifier(tableName),
-		pq.QuoteIdentifier(NotNullConstraintName(columnName))))
+	err = NewDropConstraintAction(conn, tableName, NotNullConstraintName(columnName)).Execute(ctx)
 
 	return err
 }

pkg/migrations/op_set_notnull.go

@@ -62,9 +62,7 @@ func (o *OpSetNotNull) Complete(ctx context.Context, l Logger, conn db.DB, s *sc
 	}
 
 	// Drop the NOT NULL constraint
-	_, err = conn.ExecContext(ctx, fmt.Sprintf("ALTER TABLE IF EXISTS %s DROP CONSTRAINT IF EXISTS %s",
-		pq.QuoteIdentifier(o.Table),
-		pq.QuoteIdentifier(NotNullConstraintName(o.Column))))
+	err = NewDropConstraintAction(conn, o.Table, NotNullConstraintName(o.Column)).Execute(ctx)
 	if err != nil {
 		return err
 	}

pkg/migrations/rename.go

@@ -81,12 +81,7 @@ func RenameDuplicatedColumn(ctx context.Context, conn db.DB, table *schema.Table
 				}
 
 				// Drop the constraint
-				dropConstraintSQL := fmt.Sprintf(cDropConstraintSQL,
-					pq.QuoteIdentifier(table.Name),
-					pq.QuoteIdentifier(NotNullConstraintName(column.Name)),
-				)
-
-				_, err = conn.ExecContext(ctx, dropConstraintSQL)
+				err = NewDropConstraintAction(conn, table.Name, NotNullConstraintName(column.Name)).Execute(ctx)
 				if err != nil {
 					return fmt.Errorf("failed to drop not null constraint: %w", err)
 				}