Error: `Couldn't find Course with 'id'=` when visiting `/courses/show` - ruby-on-rails

I'm new to Rails, and I'm setting up models/controllers for Course and some other models.
When I visit the /courses/show URL in my browser I get the following error:
Couldn't find Course with 'id'=
Screenshot here.
Here's the relevant line from my rake routes and routes.rb:
rake routes
courses_show GET /courses/show(.:format) courses#show
config/routes.rb
get 'courses/show'

You have specified the four routes without any :id parameter, I don't know why you would expect them to have an :id parameter.
I'd recommend that you read the Rails guide on routing and also read the comments in the generated config/routes.rb, in that file you'll see comments like this:
# Example of regular route:
# get 'products/:id' => 'catalog#view'
So, extrapolating that to your example you might end up with:
get 'courses/:id' => 'courses#show'
The example that follows that one shows how to add a named route helper using the :as option:
get 'courses/:id' => 'courses#show', as: :courses_show
Something you'll also see when you read the guide or the comments is that you can use the resources helper to create standard restful routes.

Related

rails link_to using get instead of post

I'm making a website for a class and I'm trying to implement a friend request function with a model called 'Users' and a join model called 'Relationships'. I have a button on the user#show page that should add a friend by using the create method in the Relationships controller. Here is the code for the button:
<%= link_to "Add as Friend", relationships_path(:friend_id => #user), method: :post %>
When I press the link, however, it tries to access the index method instead. After looking in the console, it looks like the link is sending a GET request, which routes to the index method, instead of a POST request, which routes to the create method. Can someone explain why this error is occurring and how I can fix it?
Edit: As requested, here is what I have in my routes:
Rails.application.routes.draw do
resources :interests
get 'interests/create'
get 'interests/destroy'
get 'home/index'
get 'sessions/create'
get 'sessions/destroy'
resources :users
resources :relationships
resources :subscriptions
# The priority is based upon order of creation: first created -> highest priority.
# See how all your routes lay out with "rake routes".
# You can have the root of your site routed with "root"
# root 'welcome#index'
root 'home#index'
get "/auth/:provider/callback" => "sessions#create"
get "/signout" => "sessions#destroy", :as => :signout
Using a link_to helper indicates to Rails that you'd like to produce an a tag in your HTML. No element of the HTML specification regarding a tags allows for producing POST requests. Because Rails understands the utility of allowing for POST and DELETE requests to be issued using links, however, it provides those options in the link_to helper. It's implementation, though, must use JavaScript under the hood in order to appropriately function.
Check that jquery-ujs is installed, and that your asset pipeline is working correctly in order to use the helper in this way.
You may also evaluate whether using a form_for and a button is better, since that will automatically POST.
I'm pretty sure you are matching the wrong route. Run rake routes and see the route that links to the Relationships#create.
Using 'url' instead of 'path' with the route helper solved the problem for me. So instead of 'relationships_path' use 'relationships_url'.

Nested routes in rails

I am someone who has always liked sinatra better than rails, and has never had to do a large enough scale project that rails was required (all the sources I have read say that rails is better for larger scale projects) and now I do have to do a large scale project. I have gotten very confused with the url structure of rails. What I am trying to do is the rails equivalent of this:
get "/" do
erb :index
end
get "/home" do
erb :dashboard
end
get "/home/profile" do
erb :profile
end
get "/home/friends" do
erb :friends
end
In the first one I understand that I should put in app/routes.rb I should put root home#index and in the home controller I should put def index end.
In the second one, I understand that I should do the same except replacing index with home.
But for the third and forth ones I have no idea what to do.
Also, is the a RESTful way to do the first two?
You probably want something like this
root 'home#index'
get 'home' => 'home#dashboard'
get 'home/profile' => 'home#profile'
get 'home/friends' => 'home#friends'
remember to use the command rake routes to see all your routes, where they lead and what their names are (if they have any)
I never understood what RESTful means, so someone else will have to answer that part of your question.
K M Rakibul Islam has shown you what can be called a "resourceful" way to do routes (because it uses the keyword resources) but it looks like you're just doing the static pages at this stage, so it's not necessary.
The simplest way to do routes is with this formula:
method url => controller::action, as: route_name
where method can be get, post, patch or delete so you can have different actions linked to the same URL depending on the method the request uses.
Putting a name on the route is optional, but it gives you a clean way to use the route in your views (route_name_path)
When you start making models then you'll find that using the resources keyword comes in handy. Read about it.
You can have this:
resources :home do
collection do
get :profile
end
collection do
get :friends
end
end
end
This will give you routes like this:
profile_home_index GET /home/profile(.:format) home#profile
friends_home_index GET /home/friends(.:format) home#friends
The standard way of declaring the root path:
root 'home#index'
And for the 2nd one, you have to do:
get 'home' => 'home#dashboard'
which will give you this route:
GET /home(.:format) home#dashboard
One route can be defined in many ways that works. But, Rails has conventions that should be followed while defining routes in your Rails app.
I would highly recommend you to take a look at the Rails Routing Guide

Migrating Routes to Rails 4

I am about to migrate my rails 3 application to rails 4.
There are some additional routes on my ressources that make some problems.
I get an error message for this lines in my route file:
resources :teams do
...
get 'apply' => 'teams#apply_membership', as: :apply_membership
post 'apply' => 'teams#apply_membership_save', as: :apply_membership
...
This is the generated error message
You may have defined two routes with the same name using the `:as` option, or you may be overriding a route already defined by a resource with the same naming. For the latter, you can restrict the routes created with `resources` as explained here:
http://guides.rubyonrails.org/routing.html#restricting-the-routes-created
In rails3 it was possible to define a get and a post route using the same alias and routing them to different controler methods.
Can I do this in rails4, too?
And if yes, how does it have to look like in my route file?
You can not take two route name with same name. but you have done it. so please change,
get 'apply' => 'teams#apply_membership', as: :apply_membership
post 'apply' => 'teams#apply_membership_save', as: :update_membership
Take a look here for rails routings. http://guides.rubyonrails.org/routing.html

Question about routes.rb

Rails newbie here.
Can anyone please explain the difference to me between the following lines of code:
match '/' => 'posts#index'
and
match '/' => 'posts#index', :as => 'posts'
The reason I'm asking is because when I use the latter code, I cannot create new posts :|
The latter is creating a named route. It creates a helper that you can call from your views, in this case, posts_path & posts_url.
That being said, I'm not sure how you are able to create new posts with either of those as you are not defining the posts#new or posts#create. Is there more to your routes file than these? Also, I'm not sure if it's a requirement or not, but you should pass your :as option as a symbol, so :as => :posts.
For reference, you can run rake routes from console and see a list of all the routes that are defined in your application. You'll also see how they are named—that's the column all the way to the right—which you can then append _path or _url to.

A very basic issue with routes in ruby

I am new to ruby and while creating a sample application found out an issue that whenever I go to http://127.0.0.1:3000/people/index by default show action is executed and index is taken as a parameter. This is server log:
Started GET "/people/index" for
127.0.0.1 at 2010-12-23 18:43:01 +0500 Processing by PeopleController#show as
HTML Parameters: {"id"=>"index"}
I have this in my route file:
root :to => "people#index"
resources :people
match ':controller(/:action(/:id(.:format)))'
What is going on here and how can I fix the issue?
The route
resources :people
creates "sub"-routes
get '/people' => 'people#index'
get '/people/new' => 'people#new'
post '/people' => 'people#create'
get '/people/:id' => 'people#show'
get '/people/:id/edit' => 'people#edit'
put '/people/:id' => 'people#update'
delete '/people/:id' => 'people#destroy'
Actually, all of these sub-routes include (.:format) at the end of the recognized path.
The path /people/index would be recognized by the route /people/:id, mapping to the action #show.
The path /people would be recognized by the route /people, mapping to the action #index.
Use the URL helpers people_path and people_url for the /people route.
To get Rails to travel backward in time to before it espoused REST and to understand /people/index, do this:
resources :people do
get :index => 'people#index'
end
You might want to watch this Railscast episode.
A couple things to keep in mind when working with your routes:
rake routes dumps the map of URLs to your controllers
When providing backwards compatibility, redirect the user to the correct path
I personally have yet to upgrade my app to Rails 3, and I'll be dragging my feet until I really need to do it (just got it out the door not too long ago). In Rails 2.x you had resource routes, but if you kept the default controller/action/id route it would fall through and resolve. It appears that is no longer the case in Rails 3. Essentially your resource routes handle all URLs in that resource namespace (/people in your case).
To provide backwards compatibility, I would add a redirect route to resolve that incompatibility.
match "/people/index", :to => redirect("/people")
The main reason for that is to prevent users from saving an incorrect URL for their personal links--while allowing legacy users to still be able to get where they meant to go.
Edit: New answer, removed pointing out the typo in the question.

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