ko.mapping.fromJS 3rd parameter (the target) missing in new version

[Nelson]

Hi, why there isn´t the 3rd parameter anymore in the ko.mapping.fromJS
function? (or it´s just me not finding it?)

I user to have some like like this:

function MyClass(obj){ //obj from json decode
this.fields = ko.observable('default values);
.
.
.
if(obj)
ko.mapping.fromJS(obj, { /* my rules(create etc) */ },
this);
}

var a = new MyClass({some: 'thing'});


And it used to worked very well... replacing the defaults by the "obj"
fields. When I upgraded the knockoutjs and the mapping plugin, it just
doesn´t work...

The workaround I found was:

$.extend(self, ko.mapping.fromJS(data, {}));

but why?!

[JohnEarles]

It seems to be still working for me.

Does this fiddle show what you expect: http://jsfiddle.net/WHNFf/

[Robert Bell]

What are the parameters?

BTW - awesome to finally find an example of fromJS that works for an
update. I've been looking all night on here and only see examples of
people showing how it does not work.

[JohnEarles]

Hi Robert,

In the call "ko.mapping.fromJS({attr2: 'two'}, { }, self)" the
parameters are:

data - The JavaScript object you have obtained and wish to map
options - An object literal describing any custom mapping options you
want applied (create, update, key, include, ignore, copy)
target - The JavaScript object that will be the target of the mapping

The documentation can explain the mapping options better than I can:
http://knockoutjs.com/documentation/plugins-mapping.html

[Robert Bell]

Thank you.

I'm stuck at trying to get this to work with an array of arrays. Does
fromJS only go one array level deep?

...
var TDrow = [
{ "Column": [
{ "ColumnType": "Question", "id": "5",
"displayText": "First Name", "canDelete": true, "Group": "",
"hasRule": true, "visible": true }
]
}];
....
self.TDrows = ko.mapping.fromJS(TDrow );
....
<ul data-bind="template: {name:'twoDtemplate', foreach: vm.TDrows}">
...
<script id="twoDtemplate" type="text/html">
<li data-bind="text: Column[0].displayText" ></li>
</script>
...
Error: Cannot read property 'displayText' of undefined;

[JohnEarles]

By default, yes. You can however write a custom create option that
will call mapping again on itself.

See this question for an example:

http://groups.google.com/group/knockoutjs/browse_thread/thread/2365f928ec0692ca

[JohnEarles]

Can you create a JSFiddle @ http://jsfiddle.net/? It would be easier
to try and figure out your issue with a fiddle that shows the issue.
You don't need to signup for an account, if you don't want to... you
can create an anonymous fiddle.

[Robert Bell]

I tried to reply to you but it must have not taken. Thank you so much
for the thread you pointed me to. That did the trick. My wife would
be so much happier with me if I had found you two days earlier, but
I'll be home for dinner tonight. Again, thank you.

On Jan 25, 7:37 am, JohnEarles <jear...@gmail.com> wrote:
> Can you create a JSFiddle @http://jsfiddle.net/? It would be easier