Library for validate models similar to JPA Bean validation. It provides a way to validate a dart object using constraints which we can use for validation. To check if the object is valid we need to invoke the function validate which returns an Object of type ValidationResult which contains a map of errors for every attribute of the object, for example:

Create a new dart project
Add dependencies to pubspec.yaml

...
dependencies:
  ...
  drails_validator: ^0.1.0 #change it for the latest version
  ...

dev_dependencies:
  ...
  build_runner: any
  ...

Create/edit the file main.dart in the folder bin and put next code on it:

// Copyright (c) 2015, Luis Vargas. All rights reserved. Use of this source code
// is governed by a BSD-style license that can be found in the LICENSE file.

library Validator.example;

import 'package:intl/intl.dart';
import 'package:validators/validators.dart' as validator;
import 'package:drails_validator/drails_validator.dart';

part 'main.g.dart';

enteredEmailInvalidMessage() =>
    Intl.message('The entered email is invalid', name: 'enteredEmailInvalidMessage');

valueAfterNowAreNotAllowedMessage() => Intl.message('Values after now are not allowed', name: 'valueAfterNowAreNotAllowedMessage');

enteredSSNInvalidMessage() => Intl.message('The entered SSN is invalid', name: 'enteredSSNInvalidMessage');

fieldBShouldNotBeNullIfFieldAGt123Message() => Intl.message("fieldB should not be null if fieldA is greater than 123", name: 'fieldBShouldNotBeNullIfFieldAGt123Message');

bool lowerThanOrEqualNow(DateTime dateOfBirth) => !dateOfBirth.isAfter(new DateTime.now());

bool isSSN(String ssn) => validator.matches(ssn, r'\d\d\d-\d\d-\d\d\d\d');

bool isEmail(String email) => isNotNull(email) && validator.isEmail(email);

_fieldAGt123(Person p) => p.fieldA != null && p.fieldA > 123;

@serializable
class Person extends _$PersonSerializable {
  int id;

  @Length(min: 2)
  String firstName;

  @Length(min: 2)
  String lastName;

  @ValidIf(isEmail, description: enteredEmailInvalidMessage)
  String email;

  @ValidIf(lowerThanOrEqualNow, description: valueAfterNowAreNotAllowedMessage)
  DateTime dateOfBirth;

  @ValidIf(isSSN, description: enteredSSNInvalidMessage)
  String ssn;

  int fieldA;

  @NotNull(iff: _fieldAGt123, description: fieldBShouldNotBeNullIfFieldAGt123Message)
  int fieldB;
}

main() async {
  _initMirrors();


  var invalidPerson = new Person()
        ..id = 1
        ..firstName = ''
        ..lastName = ''
        ..dateOfBirth = new DateTime(2030, 11, 9)
        ..ssn = '123',
      validPerson = new Person()
        ..id = 2
        ..firstName = 'Joe'
        ..lastName = 'Doe'
        ..email = 'joedoe@email.com'
        ..dateOfBirth = new DateTime(1989, 11, 9)
        ..ssn = '123-45-6789';

  print('invalidPerson: ${validate(invalidPerson)}');
  print('validPerson: ${validate(validPerson)}');
}

run pub run build_runner build. Then you will see that the file bin/drails_validator_sample.g.dart has been generated and it will contains the next code:

// GENERATED CODE - DO NOT MODIFY BY HAND

part of Validator.example;

// **************************************************************************
// DsonGenerator
// **************************************************************************

abstract class _$PersonSerializable extends SerializableMap {
  int get id;
  String get firstName;
  String get lastName;
  String get email;
  DateTime get dateOfBirth;
  String get ssn;
  int get fieldA;
  int get fieldB;
  void set id(int v);
  void set firstName(String v);
  void set lastName(String v);
  void set email(String v);
  void set dateOfBirth(DateTime v);
  void set ssn(String v);
  void set fieldA(int v);
  void set fieldB(int v);

  operator [](Object __key) {
    switch (__key) {
      case 'id':
        return id;
      case 'firstName':
        return firstName;
      case 'lastName':
        return lastName;
      case 'email':
        return email;
      case 'dateOfBirth':
        return dateOfBirth;
      case 'ssn':
        return ssn;
      case 'fieldA':
        return fieldA;
      case 'fieldB':
        return fieldB;
    }
    throwFieldNotFoundException(__key, 'Person');
  }

  operator []=(Object __key, __value) {
    switch (__key) {
      case 'id':
        id = __value;
        return;
      case 'firstName':
        firstName = __value;
        return;
      case 'lastName':
        lastName = __value;
        return;
      case 'email':
        email = __value;
        return;
      case 'dateOfBirth':
        dateOfBirth = fromSerializedDateTime(__value);
        return;
      case 'ssn':
        ssn = __value;
        return;
      case 'fieldA':
        fieldA = __value;
        return;
      case 'fieldB':
        fieldB = __value;
        return;
    }
    throwFieldNotFoundException(__key, 'Person');
  }

  Iterable<String> get keys => PersonClassMirror.fields.keys;
}

// **************************************************************************
// MirrorsGenerator
// **************************************************************************

_Person__Constructor([positionalParams, namedParams]) => new Person();

const $$Person_fields_id = const DeclarationMirror(name: 'id', type: int);
const $$Person_fields_firstName = const DeclarationMirror(
    name: 'firstName',
    type: String,
    annotations: const [
      const Length(min: 2, max: null, description: lengthShouldBeBetweenMessage)
    ]);
const $$Person_fields_lastName = const DeclarationMirror(
    name: 'lastName',
    type: String,
    annotations: const [
      const Length(min: 2, max: null, description: lengthShouldBeBetweenMessage)
    ]);
const $$Person_fields_email = const DeclarationMirror(
    name: 'email',
    type: String,
    annotations: const [
      const ValidIf(isEmail, description: enteredEmailInvalidMessage, iff: null)
    ]);
const $$Person_fields_dateOfBirth = const DeclarationMirror(
    name: 'dateOfBirth',
    type: DateTime,
    annotations: const [
      const ValidIf(lowerThanOrEqualNow,
          description: valueAfterNowAreNotAllowedMessage, iff: null)
    ]);
const $$Person_fields_ssn = const DeclarationMirror(
    name: 'ssn',
    type: String,
    annotations: const [
      const ValidIf(isSSN, description: enteredSSNInvalidMessage, iff: null)
    ]);
const $$Person_fields_fieldA =
    const DeclarationMirror(name: 'fieldA', type: int);
const $$Person_fields_fieldB =
    const DeclarationMirror(name: 'fieldB', type: int, annotations: const [
  const NotNull(
      description: fieldBShouldNotBeNullIfFieldAGt123Message, iff: _fieldAGt123)
]);

const PersonClassMirror =
    const ClassMirror(name: 'Person', constructors: const {
  '': const FunctionMirror(name: '', $call: _Person__Constructor)
}, fields: const {
  'id': $$Person_fields_id,
  'firstName': $$Person_fields_firstName,
  'lastName': $$Person_fields_lastName,
  'email': $$Person_fields_email,
  'dateOfBirth': $$Person_fields_dateOfBirth,
  'ssn': $$Person_fields_ssn,
  'fieldA': $$Person_fields_fieldA,
  'fieldB': $$Person_fields_fieldB
}, getters: const [
  'id',
  'firstName',
  'lastName',
  'email',
  'dateOfBirth',
  'ssn',
  'fieldA',
  'fieldB'
], setters: const [
  'id',
  'firstName',
  'lastName',
  'email',
  'dateOfBirth',
  'ssn',
  'fieldA',
  'fieldB'
]);

// **************************************************************************
// InitMirrorsGenerator
// **************************************************************************

_initMirrors() {
  initClassMirrors({Person: PersonClassMirror});
}

Finally you can run the file bin/drails_validator_sample.dart. If everything is ok you will see next output in console:

invalidPerson: isValid: false, errors: {firstName: [Length should be greather than 2], lastName: [Length should be greather than 2], email: [The entered email is invalid], dateOfBirth: [Values after now are not allowed], ssn: [The entered SSN is invalid]}
validPerson: isValid: true, errors: {}

Add Localization

install l10n package by running:

pub global activate l10n

generate translations by running:

mkl10n -l es . <path-to-drails_validator-package>

Warning

Remember to replace <path-to-drails_validator-package> by the correct path

translate intl_es.arb file using Google Translate Toolkit
run again:

mkl10n -l es . <path-to-drails_validator-package>

import the generated messages_all.dart file in the main.dart file:

import 'package:drails_validator_example/_l10n/messages_all.dart';

then set the default locale and initialize the messages by adding next code to main function:

main() {
...
  Intl.defaultLocale = 'es';
  await initializeMessages('es');
...
}

final code in main.dart:

// Copyright (c) 2015, Luis Vargas. All rights reserved. Use of this source code
// is governed by a BSD-style license that can be found in the LICENSE file.

library Validator.example;

import 'package:drails_validator_example/_l10n/messages_all.dart';
import 'package:intl/intl.dart';
import 'package:validators/validators.dart' as validator;
import 'package:drails_validator/drails_validator.dart';

part 'main.g.dart';

enteredEmailInvalidMessage() =>
    Intl.message('The entered email is invalid', name: 'enteredEmailInvalidMessage');

valueAfterNowAreNotAllowedMessage() => Intl.message('Values after now are not allowed', name: 'valueAfterNowAreNotAllowedMessage');

enteredSSNInvalidMessage() => Intl.message('The entered SSN is invalid', name: 'enteredSSNInvalidMessage');

fieldBShouldNotBeNullIfFieldAGt123Message() => Intl.message("fieldB should not be null if fieldA is greater than 123", name: 'fieldBShouldNotBeNullIfFieldAGt123Message');

bool lowerThanOrEqualNow(DateTime dateOfBirth) => !dateOfBirth.isAfter(new DateTime.now());

bool isSSN(String ssn) => validator.matches(ssn, r'\d\d\d-\d\d-\d\d\d\d');

bool isEmail(String email) => isNotNull(email) && validator.isEmail(email);

_fieldAGt123(Person p) => p.fieldA != null && p.fieldA > 123;

@serializable
class Person extends _$PersonSerializable {
  int id;

  @Length(min: 2)
  String firstName;

  @Length(min: 2)
  String lastName;

  @ValidIf(isEmail, description: enteredEmailInvalidMessage)
  String email;

  @ValidIf(lowerThanOrEqualNow, description: valueAfterNowAreNotAllowedMessage)
  DateTime dateOfBirth;

  @ValidIf(isSSN, description: enteredSSNInvalidMessage)
  String ssn;

  int fieldA;

  @NotNull(iff: _fieldAGt123, description: fieldBShouldNotBeNullIfFieldAGt123Message)
  int fieldB;
}

main() async {
  _initMirrors();

  Intl.defaultLocale = 'es';
  await initializeMessages('es');

  var invalidPerson = new Person()
        ..id = 1
        ..firstName = ''
        ..lastName = ''
        ..dateOfBirth = new DateTime(2030, 11, 9)
        ..ssn = '123',
      validPerson = new Person()
        ..id = 2
        ..firstName = 'Joe'
        ..lastName = 'Doe'
        ..email = 'joedoe@email.com'
        ..dateOfBirth = new DateTime(1989, 11, 9)
        ..ssn = '123-45-6789';

  print('invalidPerson: ${validate(invalidPerson)}');
  print('validPerson: ${validate(validPerson)}');
}

Edit the README file

Please don’t edit the README.md file since this one is generated by asciidoctor and pandoc. Instead edit _README.adoc and then run:

asciidoctor _README.adoc

and then:

pandoc -f docbook -t gfm -o README.md _README.adoc

drails-dart/drails_validator

Add Localization

Edit the README file