Convert SQL ENUM to Sequelize DataTypes.ENUM

ENUM Types in Sequelize

SQL ENUM columns restrict values to a predefined set. Sequelize provides DataTypes.ENUM which enforces the same constraint at the ORM level and generates appropriate database-level constraints.

Basic ENUM Conversion

CREATE TABLE orders (
  id SERIAL PRIMARY KEY,
  status ENUM('pending', 'processing', 'shipped', 'delivered') NOT NULL DEFAULT 'pending',
  priority ENUM('low', 'medium', 'high') DEFAULT 'medium'
);

Order.init({
  id: { type: DataTypes.INTEGER, primaryKey: true, autoIncrement: true, allowNull: false },
  status: {
    type: DataTypes.ENUM('pending', 'processing', 'shipped', 'delivered'),
    allowNull: false,
    defaultValue: 'pending',
  },
  priority: {
    type: DataTypes.ENUM('low', 'medium', 'high'),
    allowNull: true,
    defaultValue: 'medium',
  },
}, { ... });

Database Compatibility

DataTypes.ENUM behavior varies by database:

• MySQL: Creates a native ENUM column type
• PostgreSQL: Creates a custom type via CREATE TYPE under the hood
• SQLite: Uses a CHECK constraint to enforce allowed values
• SQL Server: Uses a CHECK constraint

TypeScript Integration

When using TypeScript, define an enum or union type alongside the model:

type OrderStatus = 'pending' | 'processing' | 'shipped' | 'delivered';

interface OrderAttributes {
  id: number;
  status: OrderStatus;
}

When to Use ENUM vs String

ENUMs are ideal when you have a small, fixed set of values that rarely changes (e.g., status codes, roles, priorities). If the value set changes frequently, consider using a DataTypes.STRING with application-level validation instead, since altering ENUM values requires a database migration.