How to cancel/revert changes to an observable model (or replace model in array with untouched copy)

Question

I have a viewModel with an observableArray of objects with observable variables.

My template shows the data with an edit button that hides the display elements and s

Answer 1

I needed something similar, and I couldn't use the protected observables, as I needed the computed to update on the temporary values. So I wrote this knockout extension:

This extension creates an underscore version of each observable ie self.Comments() -> self._Comments()

ko.Underscore = function (data) {
    var obj = data;
    var result = {};
    // Underscore Property Check
    var _isOwnProperty = function (isUnderscore, prop) {
        return (isUnderscore == null || prop.startsWith('_') == isUnderscore) && typeof obj[prop] == 'function' && obj.hasOwnProperty(prop) && ko.isObservable(obj[prop]) && !ko.isComputed(obj[prop])
    }
    // Creation of Underscore Properties
    result.init = function () {
        for (var prop in obj) {
            if (_isOwnProperty(null, prop)) {
                var val = obj[prop]();
                var temp = '_' + prop;
                if (obj[prop].isObservableArray)
                    obj[temp] = ko.observableArray(val);
                else
                    obj[temp] = ko.observable(val);
            }
        }
    };
    // Cancel
    result.Cancel = function () {
        for (var prop in obj) {
            if (_isOwnProperty(false, prop)) {
                var val = obj[prop]();
                var p = '_' + prop;
                obj[p](val);
            }
        }
    }
    // Confirm
    result.Confirm = function () {
        for (var prop in obj) {
            if (_isOwnProperty(true, prop)) {
                var val = obj[prop]();
                var p = prop.replace('_', '');
                obj[p](val);
            }
        }
    }
    // Observables
    result.Properties = function () {
        var obs = [];
        for (var prop in obj) {
            if (typeof obj[prop] == 'function' && obj.hasOwnProperty(prop) && ko.isObservable(obj[prop]) && !ko.isComputed(obj[prop])) {
                var val = obj[prop]();
                obs.push({ 'Name': prop, 'Value': val });
            }
        }
        return obs;
    }

    if (obj != null)
        result.init();

    return result;
}

This extension will save you writing duplicates of each of your observables and ignores your computed. It works like this:

var BF_BCS = function (data) {
    var self = this;

    self.Score = ko.observable(null);
    self.Comments = ko.observable('');

    self.Underscore = ko.Underscore(self);

    self.new = function () {
        self._Score(null);
        self._Comments('');
        self.Confirm();
    }

    self.Cancel = function () {
        self.Pause();
        self.Underscore.Cancel();
        self.Resume();
    }

    self.Confirm = function () {
        self.Pause();
        self.Underscore.Confirm();
        self.Resume();
    }

    self.Pause = function () {

    }

    self.Resume = function () {

    }

    self.setData = function (data) {
        self.Pause();

        self._Score(data.Score);
        self._Comments(data.Comments);
        self.Confirm();
        self.Resume();
    }

    if (data != null)
        self.setData(data);
    else
        self.new();
};

So as you can see if you have buttons on html:

<div class="panel-footer bf-panel-footer">
    <div class="bf-panel-footer-50" data-bind="click: Cancel.bind($data)">
        Cancel
    </div>
    <div class="bf-panel-footer-50" data-bind="click: Confirm.bind($data)">
        Save
    </div>
</div>

Cancel will undo and revert your observables back to what they were, as were save will update the real values with the temp values in one line

Answer 2

Very old question, but I just did something very similar and found a very simple, quick, and effective way to do this using the mapping plugin.

Background; I am editing a list of KO objects bound using a foreach. Each object is set to be in edit mode using a simple observable, which tells the view to display labels or inputs.

The functions are designed to be used in the click binding for each foreach item.

Then, the edit / save / cancel is simply:

this.edit = function(model, e)
{
    model.__undo = ko.mapping.toJS(model);
    model._IsEditing(true);
};

this.cancel = function(model, e)
{
    // Assumes you have variable _mapping in scope that contains any 
    // advanced mapping rules (this is optional)
    ko.mapping.fromJS(model.__undo, _mapping, model);
    model._IsEditing(false);
};

this.save = function(model, e)
{
    $.ajax({
        url: YOUR_SAVE_URL,
        dataType: 'json',
        type: 'POST',
        data: ko.mapping.toJSON(model),
        success: 
            function(data, status, jqxhr)
            {
                model._IsEditing(false);
            }
    }); 
};

This is very useful when editing lists of simple objects, although in most cases I find myself having a list containing lightweight objects, then loading a full detail model for the actual editing, so this problem does not arise.

You could add saveUndo / restoreUndo methods to the model if you don't like tacking the __undo property on like that, but personally I think this way is clearer as well as being a lot less code and usable on any model, even one without an explicit declaration.

Answer 3

I ran across this post while looking to solve a similar problem and figured I would post my approach and solution for the next guy.

I went with your line of thinking - clone the object and repopulate with old data on "undo":

1) Copy the data object into a new page variable ("_initData") 2) Create Observable from original server object 3) on "undo" reload observable with unaltered data ("_initData")

Simplified JS: var _viewModel; var _initData = {};

$(function () {
    //on initial load
    $.post("/loadMeUp", {}, function (data) {
        $.extend(_initData , data);
        _viewModel = ko.mapping.fromJS(data);
    });

    //to rollback changes
    $("#undo").live("click", function (){
        var data = {};
        $.extend(data, _initData );
        ko.mapping.fromJS(data, {}, _viewModel);
    });

    //when updating whole object from server
    $("#updateFromServer).live("click", function(){
        $.post("/loadMeUp", {}, function (data) {
            $.extend(_initData , data);
            ko.mapping.fromJS(data, {}, _viewModel);
        });
    });

    //to just load a single item within the observable (for instance, nested objects)
    $("#updateSpecificItemFromServer).live("click", function(){
        $.post("/loadMeUpSpecificItem", {}, function (data) {
            $.extend(_initData.SpecificItem, data);
            ko.mapping.fromJS(data, {}, _viewModel.SpecificItem);
        });
    });

    //updating subItems from both lists
    $(".removeSpecificItem").live("click", function(){
        //object id = "element_" + id
        var id = this.id.split("_")[1];
        $.post("/deleteSpecificItem", { itemID: id }, function(data){
            //Table of items with the row elements id = "tr_" + id
            $("#tr_" + id).remove();
            $.each(_viewModel.SpecificItem.Members, function(index, value){
                if(value.ID == id)
                    _viewModel.SpecificItem.Members.splice(index, 1);
            });
            $.each(_initData.SpecificItem.Members, function(index, value){
                if(value.ID == id)
                    _initData.SpecificItem.Members.splice(index, 1);
            });
        });
    });
});

I had an object that was complicated enough that I didn't want to add handlers for each individual property.

Some changes are made to my object in real time, those changes edit both the observable and the "_initData".

When I get data back from the server I update my "_initData" object to attempt to keep it in sync with the server.

Answer 4

There are a few ways to handle something like this. You can construct a new object with the same values as your current one and throw it away on a cancel. You could add additional observables to bind to the edit fields and persist them on the accept or take a look at this post for an idea on encapsulating this functionality into a reusable type (this is my preferred method).

Answer 5

You might consider using KO-UndoManager for this. Here's a sample code to register your viewmodel:

viewModel.undoMgr = ko.undoManager(viewModel, {
  levels: 12,
  undoLabel: "Undo (#COUNT#)",
  redoLabel: "Redo"
});

You can then add undo/redo buttons in your html as follows:

 <div class="row center-block">
    <button class="btn btn-primary" data-bind="
      click: undoMgr.undoCommand.execute, 
      text: undoMgr.undoCommand.name, 
      css: { disabled: !undoMgr.undoCommand.enabled() }">UNDO</button>
    <button class="btn btn-primary" data-bind="
      click: undoMgr.redoCommand.execute, 
      text: undoMgr.redoCommand.name, 
      css: { disabled: !undoMgr.redoCommand.enabled() }">REDO</button>
  </div> 

And here's a Plunkr showing it in action. To undo all changes you'll need to loop call undoMgr.undoCommand.execute in javascript until all the changes are undone.