Custom Validator

Sometimes, certain fields require custom validations that are too specialized to generalize in a standard validator. For this purpose, a custom function may be provided in order to manually process the field’s value.

Usage

const schema = new PerfectSchema({
  password: {
    type: String,
    custom(value, self, context) {
      const field = self.getField('confirmPassword');

      return !field.exists || (field.value !== value) ? 'mismatch' : undefined;
    }
  },
  confirmPassword: {
    type: String
  }
});

Custom validators

The custom validator function receives three (3) arguments and is expected to return undefined or a String, whether the field is valid or not. If the field value is not valid, the returned value is the error message to set in the validator.

The arguments represents the value, the field’s self information, and the actual validation context.

The field’s self information is an object providing extra functionality when validating the value.

• self.fieldName : String The field name being validated (not canonized).

• self.options : Object An object having all the options provided to the validation method of the context.

• self.getField(fieldName) : Object Get the current model’s field. Useful when validating against other fields. The return value will specify if the given field exists on the model, and the actual value from the model (or undefined otherwise).

  The argument fieldName may contain dots, which will make the function drill down into the model.

Extended schema field options

• custom : function The custom function. The field value will be validated against the specified function. The validation function should return undefined if the value is valid, or a string representing the error message.

  • :small_blue_diamond: value : mixed The value to validate.

  • :small_blue_diamond: self : object The current model’s field information and validation options.

  • :small_blue_diamond: context : ValidationContext The validation context.