Rails custom route using another models id

Question

I want to create a custom route such as 'photos/:user_id/:photo_id' for showing each photo. In my routes file I have;

get 'photos/:user_id/:photo_id' => 'photos#show', :as => 'user_photo'

and rake routes gives me

user_photo GET       /photos/:user_id/:photo_id(.:format)   photos#show

Edit;

Now when I link to a photo using link_to 'some photo', user_photo_path(@photo,@user) I just get the following error

Processing by PhotosController#show as HTML
  Parameters: {"user_id"=>"8", "photo_id"=>"8"}
  User Load (0.6ms)  SELECT  "users".* FROM "users"  WHERE "users"."id" = 8  ORDER BY "users"."id" ASC LIMIT 1
Completed 404 Not Found in 3ms

ActiveRecord::RecordNotFound - Couldn't find Photo without an ID:
  activerecord (4.1.1) lib/active_record/relation/finder_methods.rb:402:in `find_with_ids'
  activerecord (4.1.1) lib/active_record/relation/finder_methods.rb:68:in `find'
  activerecord (4.1.1) lib/active_record/querying.rb:3:in `find'
   () Users/batman/code/myapp/app/controllers/photos_controller.rb:73:in `set_photo'

try user_photo_path(photo_id: @photo.id, user_id: @photo.user_id) — Roman Kiselenko
– Roman Kiselenko, Commented Jun 19, 2014 at 8:55

Roman Kiselenko · Accepted Answer · 2014-06-19 09:16:17Z

4

You need to add it to params:

link_to 'some photo', user_photo_path(@photo.user, @photo)

The second error is caused by the way you are looking for a photo. Most likely you do:

photo = Photo.find(params[:id])

If that's the case you need either to change params[:id] to parmas[:photo_id] (may brake other actions if this is done in before_filter or change your route to:

get 'photos/:user_id/:id' => 'photos#show', :as => 'user_photo'

edited Jun 19, 2014 at 9:16

Roman Kiselenko

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answered Jun 19, 2014 at 9:01

BroiSatse

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5 Comments

Roman Kiselenko Over a year ago

user_id available in @photo variable

Richard Peck Over a year ago

Your use of /id will cause an issue here bud!

Richard Peck Over a year ago

Nice one - was going to recommend putting up the controller too

raphael_turtle Over a year ago

that's working now thanks, though I don't understand why using :photo_id causes the error and :id doesn't...?

BroiSatse Over a year ago

@raphael_turtle - You have set_photo before_filter in your controller which is using params[:id]. This filter is run before the show action, which results in Photo.find(nil) - which is the cause of the issue.

Richard Peck · Accepted Answer · 2014-06-19 09:45:33Z

I was writing this answer, so I'll continue

--

Routes

Shallow nesting could be a better way to do it:

#config/routes.rb
resources :users do 
    resources :photos, shallow: true #-> /user/photos/:id
end

--

Find

The problem you have (had) is that although you're sending the right params, your controller will likely not be able to build a model with the code you have.

BroiStatse mentioned you should change Photo.find(params[:id]) - the reason for this is that when you use Model.find ___, you're telling the Model to look up the primary key in your datatable based on the values you pass to it

Using params[:id] is fine if you have the id param set (as it is most of the time). However, you don't have it set, leading to your controller being unable to find the record:

Parameters: {"user_id"=>"8", "photo_id"=>"8"}

These are the params you're receiving - your error is thus:

ActiveRecord::RecordNotFound - Couldn't find Photo without an ID

Basically means you've not a param set for the find method. To fix this, you should use the photo_id param:

#app/controllers/photos_controller.rb
def show
    photo = Photo.find params[:photo_id]
end

--

Params

When you request a controller action in your application, you'll basically be sending Rails a series of params which it can then use in the controller.

These params are part of a hash, which you'll be able to call with params[:id] etc:

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