How to create JSON string in rails app

Question

So I'm using TimelineJS (http://timeline.verite.co/) and I'm in a Rails app.

And I need to find out how to generate a suitable JSON string for use with TimelineJS.

So given the demonstration JSON string below.....what do I need to do to my app in order to recreate this JSON string?

(https://github.com/VeriteCo/TimelineJS#json) The example JSON the TimelineJS developers demonstrate looks like so...

var dataObject = {
"timeline":
{
    "headline":"The Main Timeline Headline Goes here",
    "type":"default",
    "text":"<p>Intro body text goes here, some HTML is ok</p>",
    "asset": {
        "media":"http://yourdomain_or_socialmedialink_goes_here.jpg",
        "credit":"Credit Name Goes Here",
        "caption":"Caption text goes here"
    },
    "date": [
        {
            "startDate":"2011,12,10",
            "endDate":"2011,12,11",
            "headline":"Headline Goes Here",
            "text":"<p>Body text goes here, some HTML is OK</p>",
            "tag":"This is Optional",
            "classname":"optionaluniqueclassnamecanbeaddedhere",
            "asset": {
                "media":"http://twitter.com/ArjunaSoriano/status/164181156147900416",
                "thumbnail":"optional-32x32px.jpg",
                "credit":"Credit Name Goes Here",
                "caption":"Caption text goes here"
            }
        }
    ],
    "era": [
        {
            "startDate":"2011,12,10",
            "endDate":"2011,12,11",
            "headline":"Headline Goes Here",
            "text":"<p>Body text goes here, some HTML is OK</p>",
            "tag":"This is Optional"
        }

    ]
}

}

Not sure if this helps but, the schema for my app looks like so....

ActiveRecord::Schema.define(:version => 20130507031759) do

  create_table "ckeditor_assets", :force => true do |t|
    t.string   "data_file_name",                  :null => false
    t.string   "data_content_type"
    t.integer  "data_file_size"
    t.integer  "assetable_id"
    t.string   "assetable_type",    :limit => 30
    t.string   "type",              :limit => 30
    t.integer  "width"
    t.integer  "height"
    t.datetime "created_at",                      :null => false
    t.datetime "updated_at",                      :null => false
  end

  add_index "ckeditor_assets", ["assetable_type", "assetable_id"], :name => "idx_ckeditor_assetable"
  add_index "ckeditor_assets", ["assetable_type", "type", "assetable_id"], :name => "idx_ckeditor_assetable_type"

  create_table "coins", :force => true do |t|
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
    t.integer  "coin_id"
  end

  create_table "events", :force => true do |t|
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "moderations", :force => true do |t|
    t.integer  "moderatable_id"
    t.string   "moderatable_type"
    t.text     "data",             :null => false
    t.datetime "created_at",       :null => false
    t.datetime "updated_at",       :null => false
  end

  create_table "mods", :force => true do |t|
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "pages", :force => true do |t|
    t.text     "content"
    t.string   "name"
    t.string   "permalink"
    t.string   "image_url"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

  create_table "posts", :force => true do |t|
    t.string   "coin_id"
    t.text     "content"
    t.integer  "user_id"
    t.datetime "created_at",         :null => false
    t.datetime "updated_at",         :null => false
    t.string   "title"
    t.boolean  "approved"
    t.string   "photo_file_name"
    t.string   "photo_content_type"
    t.integer  "photo_file_size"
    t.datetime "photo_updated_at"
    t.integer  "event_id"
  end

  create_table "users", :force => true do |t|
    t.string   "email"
    t.string   "password_digest"
    t.boolean  "admin"
    t.datetime "created_at",                           :null => false
    t.datetime "updated_at",                           :null => false
    t.string   "spree_api_key",          :limit => 48
    t.integer  "ship_address_id"
    t.integer  "bill_address_id"
    t.string   "auth_token"
    t.string   "password_reset_token"
    t.datetime "password_reset_sent_at"
    t.string   "username"
    t.boolean  "avatar"
  end

end

So how would I go about creating a TimelineJs JSON string from this? Any ideas?

UPDATE: using advice on first answer provided below...I have this in my model and controller files respectively...but this is not working...I'm getting an "undefined method - timeline" error...what am I doing incorrectly?

coin.rb (model)

class Coin < ActiveRecord::Base
attr_accessible :coin_id

has_many :events
has_many :users, :through => :events

def timeline     
   t = {}
   t['timeline'] = {}
   t['timeline']['headline'] = "Lorem"
   t['timeline']['text'] = "default"
   t['timeline']['asset'] = ""
   t['timeline']['asset']['media'] = ""
   t['timeline']['asset']['credit'] = ""
   t['timeline']['asset']['caption'] = ""

   t['timeline']['date'] = {}
   t['timeline']['date']['startDate'] = ""
   t['timeline']['date']['endDate'] = ""
   t['timeline']['date']['headline'] = ""
   t['timeline']['date']['text'] = ""
   t['timeline']['date']['tag'] = ""
   t['timeline']['date']['classname'] = ""
   t['timeline']['date']['asset'] = ""


   t['timeline']['era'] = {}
   t['timeline']['era']['startDate'] = ""
   t['timeline']['era']['endDate'] = ""
   t['timeline']['era']['headline'] = ""
   t['timeline']['era']['text'] = ""
   t['timeline']['era']['tag'] = ""
   return t 
end

end

And inside coin_controller.rb

class CoinsController < ApplicationController

# GET /coins/1
# GET /coins/1.json
def show
  @coin = Coin.find(params[:id])
  @timeline = Coin.timeline.to_json

  respond_to do |format|
    format.html # show.html.erb
    format.json { render json: @timeline }
  end
end

end

Answer 1

You can use jbuilder to create complex JSON output. It works like a normal view. Just create a index/show.json.jbuilder template inside your views folders. Then you don't need to call render json: @timeline.

Answer 2

Rails has a built in to_json method. What you'll need to do is use a method in your model that creates a hash with this structure, and you can send it to the front end as json. For example:

class YourModel
    def timeline
      t = {}
      t['timeline'] = {}
      t['timeline']['headline'] = "Lorem ipsum"
      ...
      ...

      return t
    end
end

In your controller action:

@timeline = model.timeline.to_json

From there, you'll need to call JSON.parse() to consume the data on the front-end.