Knockout validation

Question

I have asp net mvc3 project where I do a bulk edit on a table with knockout binding  I want to do validations like required and number validations while saving data  Is there any easier way to do knock out validations  PS  I am not using forms

User · Accepted Answer

Have a look at Knockout-Validation which cleanly setups and uses what's described in the knockout documentation. Under: Live Example 1: Forcing input to be numeric

You can see it live in Fiddle

UPDATE: the fiddle has been updated to use the latest KO 2.0.3 and ko.validation 1.0.2 using the cloudfare CDN urls

To setup ko.validation:

ko.validation.rules.pattern.message = 'Invalid.';

ko.validation.configure({
    registerExtenders: true,
    messagesOnModified: true,
    insertMessages: true,
    parseInputAttributes: true,
    messageTemplate: null
});

To setup validation rules, use extenders. For instance:

var viewModel = {
    firstName: ko.observable().extend({ minLength: 2, maxLength: 10 }),
    lastName: ko.observable().extend({ required: true }),
    emailAddress: ko.observable().extend({  // custom message
        required: { message: 'Please supply your email address.' }
    })
};

User · Answer

If you don t want to use the KnockoutValidation library you can write your own  Here s an example for a Mandatory field   Add a javascript class with all you KO extensions or extenders  and add the following   ko extenders required   function  target  overrideMessage          add some sub-observables to our observable     target hasError   ko observable        target validationMessage   ko observable           define a function to do validation     function validate newValue        target hasError newValue   false   true       target validationMessage newValue        overrideMessage     This field is required                 initial validation     validate target            validate whenever the value changes     target subscribe validate          return the original observable     return target       Then in your viewModel extend you observable by   self dateOfPayment  ko observable   extend   required           There are a number of examples online for this style of validation

User · Answer

Knockout js validation is handy but it is not robust  You always have to create server side validation replica  In your case  as you use knockout js   you are sending JSON data to server and back asynchronously  so you can make user think that he sees client side validation  but in fact it would be asynchronous server side validation   Take a look at example here upida cloudapp net 8080 org upida example knockout order create clientId 1 This is a  Create Order  link  Try to click  save   and play with products  This example is done using upida library  there are spring mvc version and asp net mvc of this library  from codeplex

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