Validation

• Introduction
• Basics
  • Validating Data
  • Multiple Validation Rules
  • Validating Text Fields
  • Validation checks
• Validation Rules
• Creating Custom Validation Rules

Introduction

In Nylo, you can handle validating data using the validate helper.

It contains some useful validation rules you can use in your project.

If you need to add custom validation rules, you can do that too. In this section, we'll give an overview of how validation works in Nylo.

Validating Data

In your project, you will often need to validate data. For example, you may need to validate a user's email address or phone number when they sign up to your app.

You can use the validate helper to validate data.

class _ExampleState extends NyState<ExamplePage> {
  ...

  handleFormSuccess() {
    String textFieldPass = 'agordon@web.com';

    validate(rules: {
      "email address": [textFieldPass, "email"]
    }, onSuccess: () {
      print('looks good');
      // do something...
    });
    
    // or like this
    
    validate(rules: {
      "email address": "email" // validation rule 'email'
    }, data: {
      "email address": textFieldPass
    }, onSuccess: () {
      print('looks good');
      // do something...
    });
  }
}

When the validation passes, the onSuccess callback will be called.

If the validation fails, the onFailure callback will be called.

class _ExampleState extends NyState<ExamplePage> {
  ...
   handleFormFail() {
    String textFieldFail = 'agordon.dodgy.data';

    validate(rules: {
      "email address": [textFieldFail, "email"]
    }, onSuccess: () {
      // onSuccess would not be called
      print("success...");
    }, onFailure: (Exception exception) {
      /// handle the validation error
      print("failed validation");
    }, showAlert: false);
  }

When the validation fails, a toast notification will be displayed to the user. You can override this by setting the showAlert parameter to false.

Example using the phone_number_uk validation rule

class _ExampleState extends NyState<ExamplePage> {
  TextEditingController _textFieldController = TextEditingController();
  ...

  handleForm() {
    String textFieldValue = _textFieldController.text;

    validate(rules: {
      "phone number": [textFieldValue, "phone_number_uk"] // validation rule 'phone_number_uk'
    }, onSuccess: () {
      print('looks good');
      // do something...
    });
  }
}

Example using the contains validation rule

class _ExampleState extends NyState<ExamplePage> {
  ...

  handleForm() {
    String carModel = 'ferrari';

    validate(rules: {
      "car model": [carModel, "contains:lamborghini,ferrari"] // validation rule 'contains'
    }, onSuccess: () {
      print("Success! It's a ferrari or lamborghini");
      // do something...
    }, onFailure: (Exception exception) {
        print('No match found');
    });
  }
}

Options:

validate(
  rules: {
  "email address": "email|max:10" // checks data is an email and maximum of 10 characters
  }, data: {
    "email address": textEmail // data to be validated
  }, message: {
    "email address": "oops|it failed" // first section is title, then add a " | " and then provide the description
  },
  showAlert: true, // if you want Nylo to display the alert, default : true
  alertStyle: ToastNotificationStyleType.DANGER // choose from SUCCESS, INFO, WARNING and DANGER
);

This method is handy if you want to quickly validate the user's data and display some feedback to the user.

Multiple Validation Rules

You can pass multiple validation rules into the validate helper.

validate(rules: {
  "email address": ["john.mail@gmail.com", "email|max:10"] 
  // checks data is an email and maximum of 10 characters
}, onSuccess: () { 
    print("Success! It's a valid email and maximum of 10 characters");
});

You can also pass multiple validation rules into the validate helper like this:

validate(rules: {
  "email address": ["anthony@mail.com", "email|max:10|lowercase"], 
  // checks data is an email, lowercased and maximum of 10 characters
  "phone number": ["123456", "phone_number_uk"] 
  // checks data is a UK phone number
}, onSuccess: () { 
    print("Success! It's a valid email, lowercased and maximum of 10 characters");
}, onFailure: (Exception exception) {
    print('No match found');
});

Validating Text Fields

You can validate Text Fields by using the NyTextField widget.

Use the validationRules parameter to pass your validation rules into the TextField.

NyTextField(
  controller: _textEditingController, 
  validationRules: "not_empty|postcode_uk"
)

Validation checks

If you need to perform a validation check on data, you can use the NyValidator.isSuccessful() helper.

String helloWorld = "HELLO WORLD";

bool isSuccessful = NyValidator.isSuccessful(
    rules: {
        "Test": [helloWorld, "uppercase|max:12"]
    }
);

if (isSuccessful) {
    print("Success! It's a valid");
}

This will return a boolean value. If the validation passes, it will return true and false if it fails.

Validation Rules

Here are the available validation rules that you can use in Nylo.

email

This allows you to validate if the input is an email.

Usage: email

String email = "agordon@mail.com";

validate(rules: {
  "Email": [email, "email"]
}, onSuccess: () {
    print("Success! The input is an email");
});

boolean

This allows you to validate if the input is a boolean.

Usage: boolean

bool isTrue = true;

validate(rules: {
  "Is True": [isTrue, "boolean"]
}, onSuccess: () {
    print("Success! The input is a boolean");
});

contains

Check if the input contains a particular value.

Usage: contains:dog,cat

String favouriteAnimal = "dog";
validate(rules: {
  "Favourite Animal": [favouriteAnimal, "contains:dog,cat"]
}, onSuccess: () {
    print("Success! The input contains dog or cat");
});

url

Check if the input is a URL.

Usage: url

String url = "https://www.google.com";
validate(rules: {
  "Website": [url, "url"]
}, onSuccess: () {
    print("Success! The URL is valid");
});

min

Check if the input is a minimum of characters.

Usage: min:7 - will fail if the user's input is less than 7 characters.

// String
String password = "Password1";
validate(rules: {
  "Password": [password, "min:3"]
}, onSuccess: () {
    print("Success! The password is more than 3 characters");
});

// List
List<String> favouriteCountries = ['Spain', 'USA', 'Canada'];
validate(rules: {
  "Favourite Countries": [favouriteCountries, "min:2"]
}, onSuccess: () {
    print("Success! You have more than 2 favourite countries");
});

// Integer/Double
int age = 21;
validate(rules: {
  "Age": [age, "min:18"]
}, onSuccess: () {
    print("Success! You are more than 18 years old");
});

max

Check if the input is a maximum of characters.

Usage: max:10 - will fail if the user's input is more than 10 characters.

// String
String password = "Password1";
validate(rules: {
  "Password": [password, "max:10"]
}, onSuccess: () {
    print("Success! The password is less than 10 characters");
});

// List
List<String> favouriteCountries = ['Spain', 'USA', 'Canada'];
validate(rules: {
  "Favourite Countries": [favouriteCountries, "max:4"]
}, onSuccess: () {
    print("Success! You have less than 4 favourite countries");
});

// Integer/Double
int age = 18;
validate(rules: {
  "Age": [age, "max:21"]
}, onSuccess: () {
    print("Success! You are less than 18 years old");
});

Not Empty

Check if the input is not empty.

Usage: not_empty - will fail if the user's input is empty.

String score = "10";
validate(rules: {
  "Score": [score, "not_empty"]
}, onSuccess: () {
    print("Success! The input is not empty");
});

Regex

Check the input against a regex pattern.

Usage: r'regex:([0-9]+)' - will fail if the user's input does not match the regex pattern.

String password = "Password1!";
validate(rules: {
  "Password": [password, r'regex:^(?=.*\d)(?=.*[A-Z])(?=.*[a-z])(?=.*[^\w\d\s:])([^\s]){8,16}$']
}, onSuccess: () {
    print("Success! The password is valid");   
});

numeric

Check if the input is a numeric match.

Usage: numeric - will fail if the user's input is not numeric.

String age = '18';
validate(rules: {
  "Age": [age, "numeric"]
}, onSuccess: () {
    print("Success! The age is a number");
});

date

Check if the input is a date, e.g. 2020-02-29.

Usage: date - will fail if the user's input is not date.

// String
String birthday = '1990-01-01';
validate(rules: {
  "Birthday": [birthday, "date"]
}, onSuccess: () {
    print("Success! The birthday is a valid date");
});

// DateTime
DateTime birthday = DateTime(1990, 1, 1);
validate(rules: {
  "Birthday": [birthday, "date"]
}, onSuccess: () {
    print("Success! The birthday is a valid date");
});

capitalized

Check if the input is capitalized, e.g. "Hello world".

Usage: capitalized - will fail if the user's input is not capitalized.

String helloWorld = "Hello world";
validate(rules: {
  "Hello World": [helloWorld, "capitalized"]
}, onSuccess: () {
    print("Success! The input is capitalized");
});

lowercase

Check if the input is lowercase, e.g. "hello world".

Usage: lowercase - will fail if the user's input is not lowercased.

String helloWorld = "hello world";
validate(rules: {
  "Hello World": [helloWorld, "lowercase"]
}, onSuccess: () {
    print("Success! The input is lowercase");
});

uppercase

Check if the input is uppercase, e.g. "HELLO WORLD".

Usage: uppercase - will fail if the user's input is not uppercase.

String helloWorld = "HELLO WORLD";
validate(rules: {
  "Hello World": [helloWorld, "uppercase"]
}, onSuccess: () {
    print("Success! The input is uppercase");
});

US Phone Number

Check if the input is a valid US Phone Number, e.g. "123-456-7890".

Usage: phone_number_us - will fail if the user's input is not a US phone number.

String phoneNumber = '123-456-7890';
validate(rules: {
  "Phone Number": [phoneNumber, "phone_number_us"]
}, onSuccess: () {
    print("Success! The phone number is a valid format");
});

UK Phone Number

Check if the input is a valid UK Phone Number, e.g. "07123456789".

Usage: phone_number_uk - will fail if the user's input is not a UK phone number.

String phoneNumber = '07123456789';
validate(rules: {
  "Phone Number": [phoneNumber, "phone_number_uk"]
}, onSuccess: () {
    print("Success! The phone number is a valid format");
});

US Zipcode

Check if the input is a valid US Zipcode, e.g. "33125".

Usage: zipcode_us - will fail if the user's input is not a US Zipcode.

String zipcode = '33120';
validate(rules: {
  "Zipcode": [zipcode, "zipcode_us"]
}, onSuccess: () {
    print("Success! The zipcode is valid");
});

UK Postcode

Check if the input is a valid UK Postcode, e.g. "B3 1JJ".

Usage: postcode_uk - will fail if the user's input is not a UK Postcode.

String postcode = 'B3 1JJ';
validate(rules: {
  "Postcode": [postcode, "postcode_uk"]
}, onSuccess: () {
    print("Success! The postcode is valid");
});

Date age is younger

Check if the input is a date and is younger than a certain age, e.g. "18".

Usage: date_age_is_younger:21 - will fail if the user's input is not a date and is younger than 21.

You can validate against a DateTime or a String

// DateTime
DateTime userBithday = DateTime(2000, 1, 1);
validate(rules: {
  "Birthday": [userBithday, "date_age_is_older:30"]
}, onSuccess: () {
  print("Success! You're younger than 30");
}, onFailure: (Exception exception) {
  print('You are not younger than 30');
});

// String
String userBithday = '2000-01-01';
validate(rules: {
  "Birthday": [userBithday, "date_age_is_older:30"]
}, onSuccess: () {
  print("Success! You're younger than 30");
}, onFailure: (Exception exception) {
  print('You are not younger than 30');
});

Date age is older

Check if the input is a date and is older than a certain age, e.g. "18".

Usage: date_age_is_older:40 - will fail if the user's input is not a date and is older than 40.

You can validate against a DateTime or a String

// DateTime
DateTime userBithday = DateTime(2000, 1, 1);
validate(rules: {
  "Birthday": [userBithday, "date_age_is_older:18"]
}, onSuccess: () {
  print("Success! You're older than 18");
}, onFailure: (Exception exception) {
  print('You are not older than 18');
});

// String
String userBithday = '2000-01-01';
validate(rules: {
  "Birthday": [userBithday, "date_age_is_older:18"]
}, onSuccess: () {
  print("Success! You're older than 18");
}, onFailure: (Exception exception) {
  print('You are not older than 18');
});

Date in past

Check if the input is a date and is in the past.

Usage: date_in_past - will fail if the user's input is not a date and is in the past.

// String
String birthday = '1990-01-01';
validate(rules: {
  "Birthday": [birthday, "date_in_past"]
}, onSuccess: () {
    print("Success! The birthday is in the past");
});

// DateTime
DateTime birthday = DateTime(2030, 1, 1);
validate(rules: {
  "Coupon Date": [birthday, "date_in_past"]
}, onSuccess: () {
    print("Success! The birthday is in the past");
});

Date in future

Check if the input is a date and is in the future.

Usage: date_in_future - will fail if the user's input is not a date and is in the future.

// String
String couponDate = '2030-01-01';
validate(rules: {
  "Coupon Date": [couponDate, "date_in_future"]
}, onSuccess: () {
    print("Success! The coupon date is in the future");
});

// DateTime
DateTime couponDate = DateTime(2030, 1, 1);
validate(rules: {
  "Coupon Date": [couponDate, "date_in_future"]
}, onSuccess: () {
    print("Success! The coupon date is in the future");
});

Is True

Check if the input is true.

Usage: is_true - will fail if the user's input is not true.

bool hasAgreedToTerms = true;
validate(rules: {
  "Terms of service": [hasAgreedToTerms, "is_true"]
}, onSuccess: () {
    print("Success! You have agreed to the terms of service");
});

Is False

Check if the input is false.

Usage: is_false - will fail if the user's input is not false.

bool hasNotifications = false;

validate(rules: {
  "Phone Compatible": [hasNotifications, "is_false"]
}, onSuccess: () {
    // handle the success case
});

Password v1

Checks for a password that contains:
- At least one upper case letter
- At least one digit
- Minimum of 8 characters

Usage: password_v1 - will fail if the user's input is not a valid password.

String password = "PrintUp1";
validate(rules: {
  "Password": [password, "password_v1"]
}, onSuccess: () {
    print("Success! The password is valid");
});

Password v2

Checks for a password that contains:
- At least one upper case letter
- At least one digit
- Minimum of 8 characters
- At least one special character

Usage: password_v2 - will fail if the user's input is not a valid password.

String password = "BlueTab1e!";
validate(rules: {
  "Password": [password, "password_v2"]
}, onSuccess: () {
    print("Success! The password is valid");
});

Custom Validation Rules

You can add custom validation rules for your project by opening the config/valdiation_rules.dart file.

The validationRules variable contains all your custom validation rules.

final Map<String, dynamic> validationRules = {
  /// Example
  // "simple_password": (attribute) => SimplePassword(attribute)
};

To define a new validation rule, first create a new class that extends the ValidationRule class. Your validation class should implement the handle method like in the below example.

class SimplePassword extends ValidationRule {
  SimplePassword(String attribute)
      : super(
      attribute: attribute,
      signature: "simple_password", // Signature for the validator
      description: "The $attribute field must be between 4 and 8 digits long and include at least one numeric digit", // Toast description when an error occurs
      textFieldMessage: "Must be between 4 and 8 digits long with one numeric digit"); // TextField validator description when an error occurs

  @override
  handle(Map<String, dynamic> info) {
    super.handle(info);

    RegExp regExp = RegExp(r'^(?=.*\d).{4,8}$');
    return regExp.hasMatch(info['data']);
  }
}

The Map<String, dynamic> info object:

/// info['rule'] = Validation rule i.e "max:12".
/// info['data'] = Data the user has passed into the validation rule.

The handle method expects a boolean return type, if the data passes validation return true and false if it doesn't.