knockout.js - knockout trim in mvvm validations -

i using knockout mvvm works fine don't want send data containing white spaces server side code. here sample code

   //regular customer     self.nameforregularcustomer = ko.observable("").extend({         required: { message: 'promotion name required' },         maxlength: {             message: 'promotion name can not exceed 100 character',             params: '100'         }     });     self.statusforregularcustomer = 1; //for create mode  1 new     self.keywordforregularcustomer = ko.observable("").extend({         required: { message: 'keyword required' },         maxlength: {             message: 'keyword can not exceed 100 character',             params: '100'         }     });     self.promotionmsgforregularcustomer = ko.observable("").extend({         required: { message: 'promotion message required' }     });     self.promotiondescforregularcustomer = ko.observable("").extend({         required: { message: 'promotion description required' }         , maxlength: {             message: 'description can not exceed 100 character',             params: '2000'         }     });     //the object stored data entered in observables     self.regularcustomerpromotion = {         name: self.nameforregularcustomer,         description: self.promotiondescforregularcustomer,         keywords: self.keywordforregularcustomer,         happymessage: self.promotionmsgforregularcustomer,         status: self.statusforregularcustomer,         promotioncustomertype: self.promotioncustomertype     }; 

i making ajax call folllowing data format

  requestpromo = ko.tojson(self.newcustomerpromotion); 

but contains data white space want trim before making api call
tried use field level

 ko.subscribable.fn.trimmed = function () {    return ko.computed({     read: function () {         return this().trim();     },     write: function (value) {         this(value.trim());        // this.valuehasmutated();     },     owner: }); 

but discards validations

try creating own tojson method on view-model , strip out unnecessary white-space yourself. knockout has 2 functions tojs , tojson. can use tojs current values javascript object or use tojson string representation.

this off top of head , i'm not sure if works this.

self.prototype.tojson = function(){   var data = ko.tojs(self.newcustomerpromotion);    return {         name: data.nameforregularcustomer.trim(),         description: data.promotiondescforregularcustomer.trim(),         keywords: data.keywordforregularcustomer.trim(),         happymessage: data.promotionmsgforregularcustomer.trim(),         status: data.statusforregularcustomer.trim(),         promotioncustomertype: data.promotioncustomertype.trim()     }; }; 

this return object ready serialized ko.tojson sent on wire.

here blog post explaining in greater detail http://www.knockmeout.net/2011/04/controlling-how-object-is-converted-to.html