Ember Array call get on the return on findBy returns undefined

Question

This seems like it would be obvious. I don't know where I'm going wrong.

in a controller, for the computed property:

totalMonthlyEsales: (->
  @findBy('key', 'value1')
).property('@each.answer')

I can ask for a property on this in my template fine.

<div>{{totalMonthlyEsales.answer}}</div>

returns "23424"

However if I try

totalMonthlyEsales: (->
  @findBy('key', 'value1').get('answer')
).property('@each.answer')

I get the error "Uncaught TypeError: Cannot call method 'get' of undefined" Ultimately I want to do something like

totalMonthlyEsales: (->
  parseInt @findBy('key', 'value1').get('answer')
).property('@each.answer')

plccDcSalesCash: (->
  parseInt @findBy('key', 'value2').get('answer')
).property('@each.answer')

otherTenderTypes: (->
  @get('plccDcSalesCash') - @get('totalMonthlyEsales')
).property('totalMonthlyEsales', 'plccDcSalesCash')

Answer 1

My guess would be that the content of the ArrayController is being populated asynchronously and though there ultimately ends up being a value returned by that computed property (that has an answer associated with it), when the computed property fires at first, there isn't a matching value, so it returns undefined and, of course, you can't call .get() on an undefined value. Since you're in coffeescript, you can just do this:

totalMonthlyEsales: (->
  @findBy('key', 'value1')?.get('answer')
).property('@each.answer')

The ? says only attempt the method call if the value returned from findBy() is truthy.