gistfile1.txt

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In our schema, we'd like to know who created a specific ``Task``. In hub.js, 
users are represented as instances of the ``hub.User`` class (or a subclass), 
and there is an API call to get the ``hub.User`` that created a particular 
record, so we'll create a computed property that calls that::

    TaskList.Task = hub.Record.extend({
        isDone: hub.attr(Boolean, { default: false }),
        description: hub.attr(String, { default: "" }),
        
        createdBy: function(key, val) {
            if (val) hub.debug("You can't change the creator of an object.");
            return hub.whoCreated(this);
        }.property().cacheable()
    });

Since this is a pretty standard thing to do, hub.js provides a pre-existing 
function that does just that::

    TaskList.Task = hub.Record.extend({
        isDone: hub.attr(Boolean, { default: false }),
        description: hub.attr(String, { default: "" }),
        
        createdBy: hub.createdBy
    });

And here's the implementation of ``hub.createdBy()``::

    hub.createdBy = function(key, val) {
        if (val) hub.debug("You can't change the creator of a record.") ;
        return hub.whoCreated(this) ;
    }.property().cacheable();

A similar function exists for the ``hub.Device`` that the record was created on.