Knockout Validation
A KnockoutJS Plugin for model and property validation
Contributors:
- Eric Barnard
- Steve Greatrex
- Cristian Trifan
- Andy Booth
- Michal Poreba
- and many others!
License: MIT
Install
Bower
bower install knockout-validation --save
NuGet
PM> Install-Package Knockout.Validation
NPM
npm install knockout.validation --save
CDN
cdnjs
- https://cdnjs.cloudflare.com/ajax/libs/knockout-validation/2.0.4/knockout.validation.js
- https://cdnjs.cloudflare.com/ajax/libs/knockout-validation/2.0.4/knockout.validation.min.js
jsdelivr
- https://cdn.jsdelivr.net/npm/knockout.validation@2.0.4/dist/knockout.validation.js
- https://cdn.jsdelivr.net/npm/knockout.validation@2.0.4/dist/knockout.validation.min.js
Getting Started
//start using it!
var myValue = ko.observable().extend({ required: true });
//oooh complexity
var myComplexValue = ko.observable().extend({
required: true,
minLength: 3,
pattern: {
message: 'Hey this doesnt match my pattern',
params: '^[A-Z0-9].$'
}
});
//or chaining if you like that
var myComplexValue = ko.observable()
myComplexValue.extend({ required: true })
.extend({ minLength: 3 })
.extend({ pattern: {
message: 'Hey this doesnt match my pattern',
params: '^[A-Z0-9].$'
}});
//want to know if all of your ViewModel's properties are valid?
var myViewModel = ko.validatedObservable({
property1: ko.observable().extend({ required: true }),
property2: ko.observable().extend({ max: 10 })
});
console.log(myViewModel.isValid()); //false
myViewModel().property1('something');
myViewModel().property2(9);
console.log(myViewModel.isValid()); //true
see more examples on the Fiddle: http://jsfiddle.net/KHFn8/5424/
Native Validation Rules
Required:
var myObj = ko.observable('').extend({ required: true });
Min:
var myObj = ko.observable('').extend({ min: 2 });
Max:
var myObj = ko.observable('').extend({ max: 99 });
MinLength:
var myObj = ko.observable('').extend({ minLength: 3 });
MaxLength:
var myObj = ko.observable('').extend({ maxLength: 12 });
Email:
var myObj = ko.observable('').extend({ email: true });
... and MANY MORE
Much thanks to the jQuery Validation Plug-In team for their work on many of the rules
Custom Validation Rules
Custom Rules
Custom Rules can be created using the simple example below. All you need is to define a validator function and a default message.
The validator function takes in the observable's value, and the params that you pass in with the extend method.
ko.validation.rules['mustEqual'] = {
validator: function (val, params) {
return val === params;
},
message: 'The field must equal {0}'
};
ko.validation.registerExtenders();
//the value '5' is the second arg ('params') that is passed to the validator
var myCustomObj = ko.observable().extend({ mustEqual: 5 });
Learn more about Custom Rules on the WIKI
Or Check out our User-Contributed Custom Rules!
HTML5 Validation Attributes
Required:
<input type="text" data-bind="value: myProp" required />
Min:
<input type="number" data-bind="value: myProp" min="2" />
<input type="week" data-bind="value:myWeek" min="2012-W03" />
<input type="month" data-bind="value:myMonth" min="2012-08" />
Max:
<input type="number" data-bind="value: myProp" max="99" />
<input type="week" data-bind="value:myWeek" max="2010-W15" />
<input type="month" data-bind="value:myMonth" min="2012-08" />
Pattern:
<input type="text" data-bind="value: myProp" pattern="^[a-z0-9].*" />
Step:
<input type="text" data-bind="value: myProp" step="3" />
Special Note, the 'MinLength' attribute was removed until the HTML5 spec fully supports it
Knockout Bindings
ValidationMessage
If you want to customize the display of your objects validation message, use the validationMessage binding:
<div>
<input type="text" data-bind="value: someValue"/>
<p data-bind="validationMessage: someValue"></p>
<div>
Check out more on Validation Bindings
Remote Validation Rules
Check out our Async Validation and jQuery AJAX Validation
Localization
Add a reference to the localization js files after the Knockout Validation plugin
<script type="text/javascript" src="knockout.validation.js"></script>
<script type="text/javascript" src="el-GR.js"></script>
<script type="text/javascript" src="fr-FR.js"></script>
<script type="text/javascript" src="de-DE.js"></script>
Apply localized messages
ko.validation.locale('el-GR');