javascript - making fields observable after ajax retrieval in knockout.js -

i wondering how can make fields observables in knockout.js ajax call without having define whole object in viewmodel. possible? here have far:

var viewmodel = {     lines: new ko.observablearray([]) }; function refreshlist(ionum) {     var data = {};     data['ionum'] = ionum;     $.ajax({     url: 'handlers/getlines.ashx',     data: data,     cache: false,     datatype: 'json',     success: function(msg) {          viewmodel.lines(msg);         //here attempting make email address field observable         /*for (var = 0; < msg.length; i++) {             viewmodel.lines()[i].emailaddress = new ko.observable(msg[i].emailaddress);          }*/          //alert(viewmodel.lines[0].emailaddress);         //ko.applybindings(viewmodel);       }  }); } 

with the mapping plugin knockout can define view model plain javascript object, returned ajax call:

var viewmodel = ko.mapping.fromjs(data); // every time data received server: ko.mapping.updatefromjs(viewmodel, data); 

i had similar situation, objects instances of javascript classes. classes defined without knockout in mind, , wanted modify them use observables instead.

i created small helper convert regular objects observable objects. can either specify observable fields, or set them in object (prototype). (i thought of doing automatically, not determine field safe convert , 1 not.)

(function() {     ko.observableobject = function(object, ko_fields) {         ko_fields = ko_fields || object._ko_fields;         if (!ko_fields) {             return object;         }         (var f_idx = 0; f_idx < ko_fields.length; f_idx++) {             var field_name = ko_fields[f_idx];             if (object[field_name] && object[field_name].__ko_proto__ !== undefined) {                 continue;             }             if (object[field_name] instanceof array) {                 var field_array = object[field_name];                 (var a_idx = 0; a_idx < field_array.length; a_idx++) {                     field_array[a_idx] = ko.observableobject(field_array[a_idx]);                 }                 object[field_name] = ko.observablearray(field_array);             } else {                 object[field_name] = ko.observable(object[field_name]);             }         }          return object;     }; })(); 

you can use classes or plain objects.

// classes. define classes without knockout-observables // user.subscriptions array of subscription objects user = function(id, name) {     this.id = id;     this.name = name;     this.subscriptions = []; };  subscription = function(type, comment) {     this.type = type;     this.comment = comment; });  // create objects var jan = new user(74619, "jan fabry"); jan.subscriptions.push(new subscription("stack overflow", "the start")); jan.subscriptions.push(new subscription("wordpress stack exchange", "blog knowledge")); var chris = new user(16891, "chris westbrook");  // convert fields in our objects observables // either define fields directly: ko.observableobject(jan, ['id', 'name', 'subscriptions']); ko.observableobject(chris, ['id', 'name', 'subscriptions']); // convert user objects, not embedded subscriptions // (since there no mapping)  // if define in class prototype, work embedded objects user.prototype._ko_fields = ['id', 'name', 'subscriptions']; subscription.prototype._ko_fields = ['type', 'comment']; ko.observableobject(jan); ko.observableobject(chris);  // works objects not created class, ajax example var observable = ko.observableobject({'id': 74619, 'name':'jan'}, ['id', 'name']);