knockout.js - knockoutjs - Ajax Form Submit and update viewModel in success callback -

i'm building huge page has 10 different sections on , using knockout event binding, etc.

each sections contains form it's own viewmodel it's fields , validation properties, etc. patterned after reading this post regarding multi-view models.

i have masterviewmodel imports lots of subviewmodels. working fine , can set observable elements auto-populate upon field input, etc.

i binding form submit function in viewmodel below.

after validate , save form fields (via ajax post), want put section read-only mode, don't know how handle on viewmodel in ajax call's success callback.

<form action="webservice.php" method="post" data-bind="submit: contactinformation.validatesubmit">   this.validatesubmit = function(formelement){      var result = ko.validation.group(this, {deep: true});     if (!this.isvalid()) {         result.showallmessages(true);         return false;     }      //actually save stuff, call ajax, submit form, etc;     //  setup promise     var posting = $.post( "./webservice.php", $(formelement).serialize() );      posting.done(function( data ) {         this.contactinformation.model_state("summary"); // uncaught typeerror: cannot call method 'model_state' of undefined          // tried line below, instead of line above...         ko.mapping.updatefromjs(this, data); // uncaught typeerror: cannot call method 'updatefromjs' of undefined      });  }; 

does have idea how this? have handle of formelement contactinformation.validatesubmit() function. need manually subscribe listener somewhere? or there way hang model off of $(formelement).data('model')?

any welcomed.

thanks, -- scott

maybe can structure call little differently form submit tied function on master view model

<form data-bind="submit: submitcontactinformation"> 

then, in view model, make call sub view model separately:

var viewmodel = function () {     var self = this;      self.contactinformation = ...import sub view model      self.iscontactinformationreadonly = ko.observable(false);      self.submitcontactinformation= function () {         //make ajax call         if( contactinformation.validatesubmit() ){             self.iscontactinformationreadonly(true);         }     }; };  var vm = new viewmodel(); ko.applybindings(vm);