Q:

Ember: Programmatically set queryParams in Mixin

I'm trying to programmatically define queryParams in an Ember.Mixin.
The mixin has a method which is called when the controller holding the mixin is initialized. 
setupQueryParams: (params) ->
  params.forEach (param) =>
    @get('queryParams').push(param)

Later in an action defined on the mixin I call @transitionToRoute({queryParams: {someParam: 'something'}}) nothing happens. However when I explicitly define my queryParams, this works.

A:

queryParams are resolved off the proto of the class, not an instance, so any init functionality wouldn't be applied in time for ember to resolve it.
This just means late binding of the queryParams isn't possible in the way you want.

