simple_form_validator

GitHub

Package for simple validation of flutter form fields.

  • Only one dependency of intl package (required for age validation)
  • Open source
  • Extensible
  • Test coverage 100%

Example

  TextFormField
(
  validator: (value) {
    return Validator.validate(value, [
      Required("Input is required"),
      ValidDateFormat("dd/MM/yyyy", "Invalid date format"),
      MaxAge(15, "dd/MM/yyyy", "You are too old"),
      MinLength(2, "Invalid minimum length")
    ]);
  },
)

Getting Started

Installation

Add simple_form_validator as dependency to your flutter project by adding this lines to pubspec.yaml.

dependencies:
  simple_form_validator: "0.1.4"

Then run flutter pub get to install required dependencies.

Check installation tab for more information

Code

Import simple_form_validator package to your dart widgets by writing:

import 'package:simple_form_validator/simple_form_validator.dart';

Now you can use Validator class to create validation logic. Here is simple validator that validates if input is not null or empty.


final invalidInput = Validator.validate("", [
  Required("Input is required"),
]);

final validInput = Validator.validate("ma", [
  Required("Input is required"),
]);

print(invalidInput); // Input is required

print(validInput); // null, means input is valid

Validation types

ValidationType(String errorMessage)

General class that all validation types need to extend. Error message errorMessage that is returned if input value doesn't satisfy condition of validation type.

MaxAge(int maxYears, String dateFormat, String errorMessage)

Validates if given date is younger than maxYears. It will also return error message if date format of input incorrect.

MinAge(int minYears, String dateFormat, String errorMessage)

Validates if given date is older than minYears. It will also return error message if date format of input is incorrect.

MaxLength(int length, String errorMessage)

Validates if given input length is equal or smaller than length.

MinLength(int length, String errorMessage)

Validates if given input length is equal or larger than length.

Regex(String expression, String errorMessage)

Validates if given input value matches pattern expression.

Required(String expression, String errorMessage)

Validates if given input value is not null or empty.

ValidDateFormat(String dateFormat, String errorMessage)

Validates if given input date matches dateFormat.

Validator

Class contains most important method for validation validate. If you have different validation types given to this method it will return error message of first validation type that input value does not satisfy.

Example:

 test
('calling validate with value that does match Required but not MinLength will return MinLength error message',
() {
  expect(
        "Invalid minimal length",
        Validator.validate("mat", [
          Required("Input is required"),
          MinLength(5, "Invalid minimal length")
  ]));
});

test
('calling validate with value that does match Required and MinLength will return null',
() {
  expect(
        null,
        Validator.validate("matej", [
        Required("Input is required"),
        MinLength(5, "Invalid minimal length")
  ]));
});

Notes

Extending ValidationType

You can extend ValidationType if you need to define and validate some other validation type.

class CustomValidationType extends ValidationType {
  CustomValidationType(super.errorMessage);

  @override
  bool isValid(String? inputValue) {
    // TODO implement validation condition
  }
}

Support

If you would like to support this library you can suggest some other validation type that is not yet implemented.

Libraries

simple_form_validator