Define a custom validation function

You can provide a custom validation function to validate a value. This function should accept an Object? and return a bool.

The typedef for the custom validation function is:

typedef CustomValidator = bool Function(Object? value);

import 'package:luthor/luthor.dart';

void main() {
  final validator = l.custom((value) => value == 42);
  print(validator.validateValue(42));
}

With Code Generation, we can use the @WithCustomValidator annotation to provide a custom validation function.

Note: The custom validation function should be a top level function when using Code Generation. Anonymous functions are not supported due to Dart limitations.

import 'package:luthor/luthor.dart';
import 'package:freezed_annotation/freezed_annotation.dart';

part 'custom_schema.freezed.dart';
part 'custom_schema.g.dart';

bool customValidatorFn(Object? value) => value == 42;

@freezed
@luthor
class CustomSchema extends _$CustomSchema {
  const factory CustomSchema({
    @WithCustomValidator(customValidatorFn) required int value,
  }) = _$CustomSchema;

  static SchemaValidationResult<CustomSchema> validate(
    Map<String, dynamic> json,
  ) =>
      _$CustomSchemaValidate(json);

  factory CustomSchema.fromJson(Map<String, dynamic> json) =>
      _$CustomSchemaFromJson(json);
}

void main() {
  print(CustomSchema.validate({'value': 42}));
}