knockout.js - Knockout.Mapping - how to unmap when I've used a custom mapping? -


i use knockout.mapping plugin not have moment object instead of crappy date:

var mappedpeople = ko.mapping.fromjs(people, {     birthdate: {         create: function(op) {             return ko.observable( moment( new date(op.data) ) );         }     } });

cool.

now, after making modifications want return entire array regular js. sounds job ko.mapping.tojs!

but how go date? tojs seems take options object can't seem find option helps this.

update: i'm aware in specific scenario of using moment.js there ways around issue coercing string , re-wrapping, underlying question how provide custom "unmapping" functions plugin.

update 2: here jsbin demonstrating issue: http://jsbin.com/uzesag/1/

i know not strictly speaking answering question of how customise unmapping itself, find useful way of handling type of situation wrap original data in observables, add computed observables (sub-observables) observables themselves. best illustrated example ...

jsbin showing moment added sub-observable on birthdate

the key snippet here ... 

    var mappedpeople = ko.mapping.fromjs(people, {       birthdate: {           create: function(op) {                var observable = ko.observable(op.data);                // attach computed 'birthdate' produces moment               observable.moment = ko.computed({                 read: function() {                   return moment( new date(observable()) );                 },                 write: function(val) {                   observable(val.todate().toisostring());                 }               });                return observable;                 }       }   });

this means when call ko.mapping.tojs or ko.mapping.tojson, original structure preserved. trick need store moment computed (to cause sync original data wrapped in observable) ... 

function vm() {   this.mapped = mappedpeople;    // read moment computed   var moment = this.mapped()[0].birthdate.moment();    // manipulate   moment.add(5, 'y');    // set   this.mapped()[0].birthdate.moment(moment);    // unmapping    this.unmapped = ko.mapping.tojson(this.mapped); }  ko.applybindings(new vm());

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