Rails 3 Return Array From Collection.each Block

Question

I'm trying to return some json to the calling action. One of the params I want to pass is an array of arrays built from looping through a collection as so:

render :json => {     
:rows => @classrooms.each do |classroom|
          [classroom.name, classroom.students.count]
        end    
}

However, this sets :rows to the entire collection as opposed to what I want:

[[classroom, students],[classroom, students],[classroom, students]]

Is there any way of looping through the collection and returning an array in a single block?

Chris Heald · Accepted Answer · 2012-11-07 22:44:18Z

4

Enumerable#map is the right tool here.

render :json => {
  :rows => @classrooms.map {|c| [c.name, c.students.count]}
}

answered Nov 7, 2012 at 22:44

Chris Heald

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1 Comment

Noz Over a year ago

Indeed, I keep forgetting about all the enumerable mixin methods!

Noz · Accepted Answer · 2012-11-07 22:52:09Z

0

Another approach... each_with_object method:

render :json => {     
:rows => @classrooms.each_with_object([]) do |classroom, a|
          a << [classroom.name, classroom.students.count]
        end    
}

edited Nov 7, 2012 at 22:52

answered Nov 7, 2012 at 22:42

Noz

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