Rails router

15 February 2017

  • rails
  • ruby
DESCRIPTION: The rails router recognises the URL's passed to the app and channels to a controller's action. It can also generate paths and URL's, so the path does not need to be hard coded into the app's view.

Documentation can be found here:

Rails Routes


When the app receives an incoming URL GET /blogs/5, the router needs to match the incoming URL with a controller. This is a :show get HTTP method, and so it would be channelled as follows

get '/bogs/:id', to: 'blogs#show'

In the blogs controller show action, you can then access the :id being passed in the URL like so:

class BlogsController < ApplicationController
  def show
    @blog = Blog.find(params[:id])

This then saves the blog object with an id of 5 to the variable @blog.

If you then edit the route to look like this:

get '/blogs/:id', to: 'blogs#show', as: 'blog'

This enables us to use the route helper in the view when using link_to:

<%= link_to 'Blog Five', blog_path(@blog) %>

NOTE: the as: is what you refer to the link_to helper path as. It can be called anything. So in our example if I wanted to change the path_helper name from blog to article, I could do and the link_to helper would be article_path(@blog).

Resource routing

There are SEVEN RESTful routes INDEX, SHOW, NEW, EDIT, CREATE, UPDATE, DESTROY. Rails has FIVE HTTP methods to channel to these RESTful routes GET, POST, PATCH, PUT, DELETE. So in practice, if the router receives an incoming request like so:

DELETE /blogs/5

If the first matching resource is resources :blogs, then router accesses the BlogsController, the show action, and runs whatever code is in there. The code in the destroy controller would usually be something like this:

def destroy
  flash[:success] = "Blog deleted"

CRUD (Create, Read, Update, Delete)

IMPORTANT: The resources :blogs creates seven different routes in the application, all mapping to the BlogsController

HTTP Verb Path Controller#Action Used for
GET /blogs blogs#index display a list of all blogs
GET /blogs/new blogs#new return an HTML form for creating a new blog
POST /blogs blogs#creates create a new blog
GET /blogs/:id blogs#show display a specific blog
GET /blogs/:id/edit blogs#edit return an HTML form for editing a blog
PATCH/PUT /blogs/:id blogs#update update a specific blog
DELETE /blogs/:id blogs#destroy delete a specific blog