aspnet-validation

Enables ASP.NET Core MVC client-side validation, without JQuery!

Install

npm install aspnet-validation es6-promise

aspnet-validation uses Promise API, which is not supported in Internet Explorer. It is recommended to use promise-polyfill or es6-promise to resolve this issue...

Alternatively, download these:

• aspnet-validation.min.js
• aspnet-validation.min.js.map

Quick Start Guide

Via <script src="...">

<script src="es6-promise.auto.min.js"></script>
<script src="aspnet-validation.min.js"></script>

// Exposes window['aspnetValidation']
var v = new aspnetValidation.ValidationService();
v.bootstrap();

Via CommonJS / Browserify

require('es6-promise').polyfill();
const aspnetValidation = require('aspnet-validation');

let v = new aspnetValidation.ValidationService();
v.bootstrap();

Via TypeScript / ES Modules

import * as ES6Promise from 'es6-promise';
import { ValidationService } from 'aspnet-validation';

ES6Promise.polyfill();
let v = new ValidationService();
v.bootstrap();

Shameless self-promotion: use instapack for painless web application client development using TypeScript!

Why?

jQuery + jQuery Validation + jQuery Validation Unobtrusive: 67.9 KB + 22.5 KB + 5.14 KB = 95.6 KB

aspnet-validation: 9.81 KB (10.26%)

• promise-polyfill: +2.58 KB = 12.4 KB (12.97%)
• es6-promise: +6.19 KB = 19 KB (19.87%)

Building the Source Code

git clone https://github.com/ryanelian/aspnet-validation.git
npm install
npm run build   # If using PowerShell: .\build.ps1

Adding Custom Validation

Example stolen from https://docs.microsoft.com/en-us/aspnet/core/mvc/models/validation

Server Code (C#)

public class ClassicMovieAttribute : ValidationAttribute, IClientModelValidator
{
    private int _year;

    public ClassicMovieAttribute(int Year)
    {
        _year = Year;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        Movie movie = (Movie)validationContext.ObjectInstance;

        if (movie.Genre == Genre.Classic && movie.ReleaseDate.Year > _year)
        {
            return new ValidationResult(GetErrorMessage());
        }

        return ValidationResult.Success;
    }

    public void AddValidation(ClientModelValidationContext context)
    {
        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        MergeAttribute(context.Attributes, "data-val", "true");
        MergeAttribute(context.Attributes, "data-val-classicmovie", GetErrorMessage());

        var year = _year.ToString(CultureInfo.InvariantCulture);
        MergeAttribute(context.Attributes, "data-val-classicmovie-year", year);
    }
}

Client Code

import { ValidationService } from 'aspnet-validation';
let v = new ValidationService();

// Must be done BEFORE bootstrap() is called!
v.addProvider('classicmovie', (value, element, params) => {
    if (!value) {
        // Let [Required] handle validation error for empty input...
        return true;
    }
    
    // data-val-classicmovie-year is bound automatically to params!
    let year = parseInt(params.year);
    let date = new Date(value);

    let genreDropdown = document.getElementById('Genre') as HTMLSelectElement;
    let genre = select.options[select.selectedIndex].value;

    if (genre && genre.length > 0 && genre === '0') {
        return date.getFullYear() <= year;
    }

    return true;
});

v.bootstrap();

Adding Custom Asynchronous Validation

Other than boolean and string, addProvider callback accepts Promise<string | boolean> as return value:

v.addProvider('io', (value, element, params) => {
    if (!value) {
        return true;
    }

    return async () => {
        let result: number = await Some_IO_Operation(value);
        return result > 0;
    };
});