Function VIRTUAL

A virtual value that is not stored in the DB. This could for example be useful if you want to provide a default value in your model that is returned to the user but not stored in the DB.

You could also use it to validate a value before permuting and storing it. Checking password length before hashing it for example:

class User extends Model {}
User.init({
  password_hash: DataTypes.STRING,
  password: {
   type: DataTypes.VIRTUAL,
   set (val) {
     this.setDataValue('password', val); // Remember to set the data value, otherwise it won't be validated
     this.setDataValue('password_hash', this.salt + val);
   },
   validate: {
     isLongEnough (val) {
       if (val.length < 7) {
         throw new Error("Please choose a longer password")
       }
     }
   }
  }
}, { sequelize });

VIRTUAL also takes a return type and dependency fields as arguments If a virtual attribute is present in attributes it will automatically pull in the extra fields as well. Return type is mostly useful for setups that rely on types like GraphQL.

{
  active: {
  type: new DataTypes.VIRTUAL(DataTypes.BOOLEAN, ['createdAt']),
  get() {
    return this.get('createdAt') > Date.now() - (7 * 24 * 60 * 60 * 1000)
  }
  }
}

In the above code the password is stored plainly in the password field so it can be validated, but is never stored in the DB.

A virtual value that is not stored in the DB. This could for example be useful if you want to provide a default value in your model that is returned to the user but not stored in the DB.

You could also use it to validate a value before permuting and storing it. Checking password length before hashing it for example:

class User extends Model {}
User.init({
  password_hash: DataTypes.STRING,
  password: {
   type: DataTypes.VIRTUAL,
   set (val) {
     this.setDataValue('password', val); // Remember to set the data value, otherwise it won't be validated
     this.setDataValue('password_hash', this.salt + val);
   },
   validate: {
     isLongEnough (val) {
       if (val.length < 7) {
         throw new Error("Please choose a longer password")
       }
     }
   }
  }
}, { sequelize });

VIRTUAL also takes a return type and dependency fields as arguments If a virtual attribute is present in attributes it will automatically pull in the extra fields as well. Return type is mostly useful for setups that rely on types like GraphQL.

{
  active: {
  type: new DataTypes.VIRTUAL(DataTypes.BOOLEAN, ['createdAt']),
  get() {
    return this.get('createdAt') > Date.now() - (7 * 24 * 60 * 60 * 1000)
  }
  }
}

In the above code the password is stored plainly in the password field so it can be validated, but is never stored in the DB.