output formated json with rails 3 - ruby-on-rails

Question

I use rails 3.0.3
A javascript auto complete needs data like this
{
query:'Li',
suggestions:['Liberia','Libyan Arab Jamahiriya','Liechtenstein','Lithuania'],
data:['LR','LY','LI','LT']
}
My action is
def autocomplete
#query = params[:query]
#customers = Customer.where('firstname like ?', "%#{#query}%")
render :partial => "customers/autocomplete.json"
end
My view is
{
query:'<%= #query %>',
suggestions: <%= raw #customers.map{|c| "#{c.firstname} #{c.lastname}" } %>,
data: <%= raw #customers.to_json %>
}
it returns
{
query:'e',
suggestions: ["customer 1", "customer 2"],
data: [1, 3]
}
it's not working because the data for suggestions/data should be between simple quote...
I cannot use the to_json method, because it'll returns all the content of my object.
Any suggestion?
cheers

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Note: this is way out of date, Jbuilder is by far a better option.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