Ruby on Rails- constraints in ruby on rails - ruby on rails tutorial - rails guides - rails tutorial - ruby rails



We can filter what routes are available using constraints.

There are several ways to use constraints including:

  • segment constraints
  • request based constraints
  • advanced constraints

example

  • requested based constraint to only allow a specific IP address to access a route:
constraints(ip: /127\.0\.0\.1$/) do
  get 'route', to: "controller#action"
end
Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team

See other similar examples ActionDispatch::Routing::Mapper::Scoping.

  • We want to do something more complex we can use more advanced constraints and create a class to wrap the logic:
# lib/api_version_constraint.rb
class ApiVersionConstraint
  def initialize(version:, default:)
    @version = version
    @default = default
  end

  def version_header
    "application/vnd.my-app.v#{@version}"
  end

  def matches?(request)
    @default || request.headers["Accept"].include?(version_header)
  end
end

# config/routes.rb
require "api_version_constraint"

Rails.application.routes.draw do
  namespace :v1, constraints: ApiVersionConstraint.new(version: 1, default: true) do
    resources :users # Will route to app/controllers/v1/users_controller.rb
  end

  namespace :v2, constraints: ApiVersionConstraint.new(version: 2) do
    resources :users # Will route to app/controllers/v2/users_controller.rb
  end
end
Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team

One form, several submit buttons

  • We can also use the value of the submit tags of a form as a constraint to route to a different action. If we have a form with multiple submit buttons (eg "preview" and "submit"), We could capture this constraint directly in our routes.rb, instead of writing javascript to change the form destination URL.
  • Example with the commit_param_routing gem we can take advantage of rails submit_tag
  • Rails submit_tag first parameter lets we change the value of our form commit parameter
# app/views/orders/mass_order.html.erb
<%= form_for(@orders, url: mass_create_order_path do |f| %>
    <!-- Big form here -->
  <%= submit_tag "Preview" %>
  <%= submit_tag "Submit" %>
  # => <input name="commit" type="submit" value="Preview" />
  # => <input name="commit" type="submit" value="Submit" />
  ...
<% end %>

# config/routes.rb
resources :orders do
  # Both routes below describe the same POST URL, but route to different actions 
  post 'mass_order', on: :collection, as: 'mass_order',
    constraints: CommitParamRouting.new('Submit'), action: 'mass_create' # when the user presses "submit"
  post 'mass_order', on: :collection,
    constraints: CommitParamRouting.new('Preview'), action: 'mass_create_preview' # when the user presses "preview"
  # Note the `as:` is defined only once, since the path helper is mass_create_order_path for the form url
  # CommitParamRouting is just a class like ApiVersionContraint
end
Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team

This ruby on rails tutorial page provides you the following key areas such as ruby , rail , ruby on rails , rail forum , ruby on rails tutorial , ruby tutorial , rails guides , rails tutorial , learn ruby , rails form_for , ruby rails , ruby class , what is ruby on rails , rails installer , ruby online , learn ruby on rails , ruby on rails jobs , rails find_by , install rails , easyrail , rubyonrails , link_to rails , ruby on rails developer , learn ruby the hard way , railscasts , ruby on rails examples , ruby on rails vs php , rails 4 , rails activerecord , rails generate , ruby and rails , ruby on rails download , install ruby on rails , ruby net http , what is rails , ruby app , ruby vs ruby on rails , ruby on rails windows , rails for zombies , ruby on rails book , ruby on rails development , ruby on rails ide , ruby on rails tutorial pdf

Related Searches to consider we are connecting mysql rds with our rails