knockout.js - knockout viewmodel property undefined

Question

I have a simple foreach:

<div id="customersArea" data-bind="foreach: people">
            <div class="section" data-bind="attr: { 'personid': PersonId }" >
                <div class="sectionActions">
                    <div><a class="action" href="#" data-bind='click: $parent.removePerson'>Remove</a></div>
                </div>
                <div class="sectionText">
                    <span data-bind="if:LastName, text:LastName"></span>
                    <span data-bind="if:FirstName, text:FirstName"></span>
                    <span data-bind="if:MailingAddress">
                        <span data-bind="with:MailingAddress">
                            <span data-bind="text:StreetPartOne"> </span>
                            <span data-bind="text:StreetPartTwo">  </span>
                            <span data-bind="text:City"></span>
                            <span data-bind="text:PostalCode"></span>
                        </span>
                    </span>

                    <span data-bind="if:EmailAddress, text:EmailAddress"></span>
                    <span data-bind="if:MainPhoneNumber, text:MainPhoneNumber"></span>
                    <span data-bind="if:MobilePhoneNumber, text:MobilePhoneNumber"></span>

                </div>

                <div class="sectionOptions">

                </div>
            </div>
        </div>

I am trying to make it such that i can bind against a model {PersonId:33} and the rest will just not render if missing. when i try it this and other ways i get

Uncaught Error: Unable to parse bindings.
Message: ReferenceError: MailingAddress is not defined;
Bindings value: if:MailingAddress

I created a simple jsfiddle to test:

http://jsfiddle.net/E7kUr/

Answer 1

So, there are a few options that you have:

1. KO will have an issue when you try to bind against undefined properties, unless they are off of an object. So, you can prefix your various bindings with $data. and KO will be able to parse your bindings. Sample: http://jsfiddle.net/rniemeyer/dLCL8/ If you know that several properties will always be together, then you could use a with or if statement around those options.

2. A different take on handling "undefined" properties is to create a binding that populates these properties when they are missing. Look at this answer. It would be similar, but potentially with the 'text' binding. Sample: http://jsfiddle.net/rniemeyer/dLCL8/4/