Including nested objects in JSON response, from MongoMapper objects - ruby-on-rails

class Api::StoresController < ApplicationController
respond_to :json
def index
#stores = Store.all(:include => :products)
respond_with #stores
end
end
Returns only stores without their products, as does
Store.find(:all).to_json(:include => :products)
The association is tested, I can see the nested products in console ouput from, say,
Store.first.products
What's the correct way to get them products included with MongoMapper?
Here are my models:
class Store
include MongoMapper::Document
many :products, :foreign_key => :store_ids
end
class Product
include MongoMapper::Document
key :store_ids, Array, :typecast => 'ObjectId'
many :stores, :in => :store_ids
end
UPDATE
In trying Scott's suggestion, I've added the following to the Store model:
def self.all_including_nested
stores = []
Store.all.each do |store|
stores << store.to_hash
end
end
def to_hash
keys = self.key_names
hash = {}
keys.each{|k| hash[k] = self[k]}
hash[:products] = self.products
hash[:services] = self.services
hash
end
And in the controller:
def index
#stores = Store.all_including_nested
respond_with #stores
end
Which looks like it should work? Assuming the array of hashes would have #to_json called on it, and then the same would happen to each hash and each Product + Service. I'm reading through ActiveSupport::JSON's source, and so far that's what I've grokked from it.
But, not working yet... :(

Have a look at the as_json() method. You put this in your models, define your json, and then simply call the render :json method and get what you want.
class Something
def as_json(options={})
{:account_name => self.account_name,
:expires_on => self.expires_on.to_s,
:collections => self.collections,
:type => "Institution"}
end
end
You'll notice self.collections which is a many relationship. That model also has as_json() defined:
class Collection
def as_json(options={})
{:name => self.name,
:title => self.title,
:isbn => self.isbn,
:publisher => self.publisher,
:monthly_views => self.monthly_views}
end
end
This one contains self.monthly_views which represents another many relationship.
Then in your controller:
#somethings = Something.all
render :json => #somethings

You might have to create your own method to generate a hash then turn the hash into JSON. I'm thinking something like this:
store = Store.first
keys = store.key_names
hash = {}
keys.each{|k| hash[k] = store[k]}
hash[:products] = store.products
hash.to_json

Related

Rails - Include association in json response

I got 2 Tables/Models: Paths and Questions. Each question belongs to a path
My question.rb:
class Question < ActiveRecord::Base
belongs_to :path
end
My path.rb
class Path < ActiveRecord::Base
has_many :questions
end
Everything works fine like
p = Path.last
Path.questions
returns everything I need but I'm returning a json response like this:
#path = Path.find_by_id(params[:id])
render :status=>200, :json => {:status => "success", :path => #path, :message => "Showing path"}
That answer doesn't include the questions for the path of course. What do I have to change to include all questions belonging to that path? I know I could just add :path_questions => #path.questions but is there no way to include the questions without a new return variable? I hope it's clear what I mean.
I do it like that in a Rails 5 API app:
BooksController
def index
#books = Book.limit(params[:limit])
render json: #books, include: ['author'], meta: { total: Book.count }
end
In the above situation, a Book belongs_to Author.
This is quite hacky, but should work:
:path => #path.as_json.merge(:questions => #path.questions.as_json)
Eventually you can override as_json inside your model:
def as_json(options={})
includes = [*options.delete(:include)]
hash = super(options)
includes.each do |association|
hash[self.class.name.underscore][association.to_s] = self.send(association).as_json
end
hash
end
And then just call: :path => #path.as_json(:include => :questions)
Note it will also add :include option to to_json method.

Rails as_json with two unrelated models

Given two models and a controller:
Apples
class Apples < ActiveRecord::Base
belongs_to :not_oranges
...
def as_json(options={})
opts = {:include => [:not_oranges]}
super(options.reverse_merge! opts)
end
end
Oranges
class Oranges < ActiveRecord::Base
belongs_to :not_apples
...
def as_json(options={})
opts = {:include => [:not_apples]}
super(options.reverse_merge! opts)
end
end
Search Controller
class SearchController < ApplicationController
a = Apples.search params[:q]
o - Oranges.search params[:q]
#results = {
:apples => a,
:oranges => o
}
respond_to do |format|
format.json { render :json => #results }
end
As you can see, the two models are completely unrelated and both have different :include options in their as_json definitions.
All works as expected if the search query only hits apples or only hits oranges, but once both objects aren't empty I get:
undefined method `not_apples' for #<Oranges:0x00000004af8cd8>
Seems either the two as_json definitions are being merged, or Oranges.as_json is being overriden by Apples.as_json.
Is this expected behaviour? Is there any clean way around it without using something like RABL? I feel it would be overkill for my needs.
In pseudo code the code for hash as_json method looks like
def as_json(options={})
Hash[collect {|key,element| [key.to_s,element.as_json(options)]}]
end
But your element is modifying the options argument you pass to it. Hash is unaware of this and so passes the modified options hash to as json.
It's usually a good idea not to modify in place the arguments passed to you, except when it is very clear this is ok. I'd rewrite your method as
def as_json(options={})
defaults = {:include => :not_apples}
super(defaults.merge(options))
end

Shortening up respond_with( :include => xxx)

I'm looking for a way to shorten up the :include => :child inside a respond_with which generates json.
Here is an example, not sure if it is even possible, but I would like to find out.
In the controller:
#p = Parent.where('id = ?', params[:id])
respond_with(#p, :include => {:child1 => {}, :child2 => {}, :child3 => {:include => :grandchild1}})
Is there someway to include these all when I define the instance?
Maybe something like:
#p = Parent.includes(:child1, :child2, :child3, :grandchild1).where('id = ?', params[:id])
respond_with(#p)
Basically, I'm trying to DRY up my code ... I don't want to have to keep typing the include hash over and over ... Is there someway to just include all child objects in one call?
ActiveRecord has an as_json method that defines how the object should be outputted as json. You can ovveride this method to include the associated children by default so something like this:
class Parent < ActiveRecord::Base
# We went to display grandchildren by default in the output JSON
def as_json(options={})
super(options.merge(:include => {:child1 => {}, :child2 => {}, :child3 => {:include => :grandchild1}})
end
end
That should let you clean up your controller a bit, you only need this:
#parent = Parent.find(params[:id])
respond_with #parent

Rails 3: alias_method_chain to set specific attribute first

When user's create a post I'd like to set the user_id attribute first. I'm trying to do this using alias_method_chain on the arrtibutes method. But I'm not sure if this is right as the problem I thought this would fix is still occurring. Is this correct?
Edit:
When my users create a post they assign 'artist(s)' to belong to each post, using a virtual attribute called 'artist_tokens'. I store the relationships in an artist model and a joined table of artist_ids and post_ids called artisanships.
I'd like to to also store the user_id of whomever created the artist that belongs to their post (and I want it inside the artist model itself), so I have a user_id column on the artist model.
The problem is when I create the artist for each post and try to insert the user_id of the post creator, the user_id keeps showing as NULL. Which is highly likely because the post's user_id attribute hasn't been set yet.
I figured to get around this I needed to set the user_id attribute of the post first, then let the rest of the attributes be set as they normally are. This is where I found alias_method_chain.
post.rb
attr_reader :artist_tokens
def artist_tokens=(ids)
ids.gsub!(/CREATE_(.+?)_END/) do
Artist.create!(:name => $1, :user_id => self.user_id).id
end
self.artist_ids = ids.split(",")
end
def attributes_with_user_id_first=(attributes = {})
if attributes.include?(:user_id)
self.user_id = attributes.delete(:user_id)
end
self.attributes_without_user_id_first = attributes
end
alias_method_chain :attributes=, :user_id_first
EDIT:
class ArtistsController < ApplicationController
def index
#artists = Artist.where("name like ?", "%#{params[:q]}%")
results = #artists.map(&:attributes)
results << {:name => "Add: #{params[:q]}", :id => "CREATE_#{params[:q]}_END"}
respond_to do |format|
format.html
format.json { render :json => results }
end
end
In your controller, why not just do this:
def create
#post = Post.new :user_id => params[:post][:user_id]
#post.update_attributes params[:post]
...
end
But it seems to me that it would be much better to create the artist records after you've done validation on the post rather than when you first assign the attribute.
EDIT
I would change this to a callback like this:
class Post < ActiveRecord::Base
attr_accessor :author_tokens
def artist_tokens=(tokens)
#artist_tokens = tokens.split(',')
end
after_save :create_artists
def create_artists
#artist_tokens.each do |token|
...
end
end
end

problem using 'as_json' in my model and 'render :json' => in my controller (rails)

I am trying to create a unique json data structure, and I have run into a problem that I can't seem to figure out.
In my controller, I am doing:
favorite_ids = Favorites.all.map(&:photo_id)
data = { :albums => PhotoAlbum.all.to_json,
:photos => Photo.all.to_json(:favorite => lambda {|photo| favorite_ids.include?(photo.id)}) }
render :json => data
and in my model:
def as_json(options = {})
{ :name => self.name,
:favorite => options[:favorite].is_a?(Proc) ? options[:favorite].call(self) : options[:favorite] }
end
The problem is, rails encodes the values of 'photos' & 'albums' (in my data hash) as JSON twice, and this breaks everything... The only way I could get this to work is if I call 'as_json' instead of 'to_json':
data = { :albums => PhotoAlbum.all.as_json,
:photos => Photo.all.as_json(:favorite => lambda {|photo| favorite_ids.include?(photo.id)}) }
However, when I do this, my :favorite => lambda option no longer makes it into the model's as_json method.......... So, I either need a way to tell 'render :json' not to encode the values of the hash so I can use 'to_json' on the values myself, or I need a way to get the parameters passed into 'as_json' to actually show up there.......
I hope someone here can help... Thanks!
Ok I gave up... I solved this problem by adding my own array methods to handle performing the operations on collections.
class Array
def to_json_objects(*args)
self.map do |item|
item.respond_to?(:to_json_object) ? item.to_json_object(*args) : item
end
end
end
class Asset < ActiveRecord::Base
def to_json_object(options = {})
{:id => self.id,
:name => self.name,
:is_favorite => options[:favorite].is_a?(Proc) ? options[:favorite].call(self) : !!options[:favorite] }
end
end
class AssetsController < ApplicationController
def index
#favorite_ids = current_user.favorites.map(&:asset_id)
render :json => {:videos => Videos.all.to_json_objects(:favorite => lambda {|v| #favorite_ids.include?(v.id)}),
:photos => Photo.all.to_json_objects(:favorite => lambda {|p| #favorite_ids.include?(p.id)}) }
end
end
I think running this line of code
render :json => {:key => "value"}
is equal to
render :text => {:key => "value"}.to_json
In other words, don't use both to_json and :json.

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