Add support for concurrency conflicts on a array item level - AndersMalmgren/Knockout.Concurrency GitHub Wiki

The getting started example does not support scenarios where items have been removed or added. To support this the engine needs to know a little more about your model. You do this by supplying a mapping literal to the runner

http://jsfiddle.net/7atZT/5/

var mappings = {  
    children: {
        key: function(item) {
            return ko.utils.unwrapObservable(item.id);
        },
        create: function(data) {
            return { id: data.id, name: data.name };
        }                            
    }
};
this.concurrencyRunner.run(this, data, mappings);

• key: used by the engine to match the rows
• create: used by the engine to create new rows
• deleted: When a existing row is deleted on the server the Id will not exist anymore in the DB. You can use the deleted method to reflect this

deleted: function(item) {
 item.id(0);
}

This way if your user choose to take his local version to resolve a conflict, backend will create a new row instead of throwing a Constraint error (This can off course also be addressed server side, but the option is there to fix it client side)