ko dirty

Attendance model

       var Attendance = function () {
            var self = this;
            self.datacontext = datacontext;
            self.sessionId = ko.observable();
            self.personId = ko.observable();
            
            // id is string compound key {personId,sessionId} like "3,10"    
            self.id = ko.computed({
                read: function () {
                    return attendanceMakeId(self.personId(), self.sessionId());
                },
                write: function (value) {
                    var idparts = value.split(",");
                    self.personId(parseInt(idparts[0]));
                    self.sessionId(parseInt(idparts[1]));
                }
            }),
            
            self.rating = ko.observable();
            self.text = ko.observable();
            self.dirtyFlag = new ko.DirtyFlag(self);
            return self;
        };

        var attendanceNullo = new Attendance()
            .sessionId(0)
            .personId(0)
            .rating(0)
            .text('');
        attendanceNullo.dirtyFlag().reset();
        attendanceNullo.isNullo = true;

ko dirty

define(['ko'], function(ko) {
    'use strict';
    ko.DirtyFlag = function (objectToTrack, isInitiallyDirty, hashFunction) {

        hashFunction = hashFunction || ko.toJSON;

        var
            _lastCleanState = ko.observable(hashFunction(objectToTrack)),
            _isInitiallyDirty = ko.observable(isInitiallyDirty),

            result = function () {
                var self = this;
                self.isDirty = ko.computed(function () {
                    return _isInitiallyDirty() || hashFunction(objectToTrack) !== _lastCleanState();
                });
                self.reset = function () {
                    _lastCleanState(hashFunction(objectToTrack));
                    _isInitiallyDirty(false);
                };
                return self;
            };
        return result;
    };
});

view model

            isDirty = ko.computed(function () {
                if (session() && session().attendance && session().attendance()) {
                    return session().attendance().dirtyFlag().isDirty();
                }
                return false;
            }),