Favouriting a picture in a Rails app - ruby-on-rails

Question

I am trying to figure out how to execute a "favourite a picture" method in a Rails app, which I am very new to, going from a JS/Meteor background.
The point is I have a User, FavPic, Pic classes:
class User < ActiveRecord::Base
#some user oauth stuff would be here
has_many :fav_pics
has_many :pics_favorited,
class_name: 'Pic',
through: :fav_pics
end
class FavPic < ActiveRecord::Base
belongs_to :user
belongs_to :pic
end
class Pic < ActiveRecord::Base
has_many :fav_pics
has_many :fav_users,
class_name: 'User',
through: :fav_pics
end
and here's my template:
<% if current_user %>
<%= form_tag(root_path, :method => "get") do %>
<p>
<%= text_field_tag :username, params[:username] %>
<%= submit_tag "Search", :name => nil %>
</p>
<% end %>
<ul>
<% #mentions.each do |mention| %>
<li>
<%= mention.text %>
<div class="row">
<% mention.media.each do |media| %>
<div class="col-xs-3">
<%=image_tag(media.media_url, class:"img-responsive")%>
<i class="fa fa-star fa-2x"></i>
</div>
<% end %>
</div>
</li>
<% end %>
</ul>
<% else %>
<p>
Sign in to be able to use the app.
</p>
<% end %>
current_user is a user signed in through Twitter and #mentions is a list of tweets that has the username inputed in the form mentioned. media.media_url is a picture url that is associated with that tweet.
I am trying to get that link (or whatever way it's done in Rails) to add that media URL into the DB so I can list all the images at a separate URL.

Answer 1

You've got a choice: change the <a href="#"> into a form, or have your action link include the url encoded url as a parameter. Either way, you can still use AJAX to invoke the call to the server.
Your server would have an action on a controller that accepted the appropriate call to mark something as a favorite. Since you don't have your Controller code listed let's call it your PicController I'm also assuming your Pic class has a url property on it.
I highly recommend this primer: http://guides.rubyonrails.org/association_basics.html and the very basic http://guides.rubyonrails.org/getting_started.html which covers how to do action links and forms.
class PicController < ApplicationController
def favorite
pic = Pic.find(params[:url])
favorite = FavPic.new
favorite.pic = pic
favorite.user = current_user # however you get at this...
favorite.save
pic.fav_users.add(favorite)
pic.save
current_user.fav_pics.add(favorite)
current_user.save
end
end
The above code covers how to create the new FavPic instance and save it appropriately.

Answer 2

Putting together that
have a current_user, that want's to add a picture to her/his favourites
pictures are identified by the url that is also the media_url in your template
You need
an action to add the picture as a favourite, i.e. in the pics_controler
a route to this action, since it's a data changeing action, it should be a POST route
so in your config/routes.rb, to define a named route add
put 'pics/:url/avourite' => 'pics#favourite', as: 'add_favourite'
and in your template change the link to
<%= link_to add_favourite_url(url: media.media_url), class: 'fav-img', method: :put do %>
<i class="fa fa-star fa-2x"></i>
<% end %>
Then in the controller:
class PicController < ApplicationController
def favorite
if current_user.present?
pic = Pic.find(params[:url])
FavPic.create pic: pic, user: current_user
# user and pic automaically have this `FavPic` assigned
end
end
end