output formated json with rails 3

Question

I use rails 3.0.3

A javascript auto complete needs data like this

{
 query:\'Li\',
 suggestions:[\'Liberia\',\'Libyan Arab Jamahiriya\',\'Liechtenstein\'         


        

Answer 1

Note: this is way out of date, Jbuilder is by far a better option.

---

There are two ways you can approach this. If you simply need a subset of the fields in an object, you can use :only or :except to exclude what you don't want.

@customer.to_json(:only => [:id, :name])

in your example it looks like you need to return json in a specific format, so simply serializing an array of results won't work. The easiest way to create a custom json response is with the Hash object:

render :json => {
  :query => 'e',
  :suggestions => @customers.collect(&:name),
  :data => @customers.collect(&:id)
}

I've tried using partials to build json responses, but that doesn't work nearly as well as simply using Hash to do it.

---

Formatting the first and last names as a single string is something you are likely to do a lot in your views, I would recommend moving that to a function:

class Customer < ActiveRecord::Base
  ...
  def name
    "#{first_name} #{last_name}"
  end

  def name=(n)
    first_name, last_name = n.split(' ', 2)
  end
end

Just some convenience functions that makes your life a little easier, and your controllers/views cleaner.

Answer 2

If Adam's response won't work for you, this may do it (admittedly not the most elegant solution):

{
    query:'<%= @query %>',
    suggestions: [<%= raw @customers.map{|c| "'#{c.firstname} #{c.lastname}'" }.join(", ") %>],
    data: [<%= raw @customers.map{|c| "'#{c.id}'" }.join(", ") %>]
}

Answer 3

I've seen something like this in a .erb:

<%= raw
  {
    :query       => @query,
    :suggestions => @customers.map{|c| "#{c.firstname} #{c.lastname}" },
    :data        => @customers
  }.to_json
%>

If thinking of preparing data to be consumed by other programs as presentation logic, this might make sense to you.

FWIW I like it.