Rails advanced routing constraint no route matches

Question

What i'm trying to do is have a constraint on my routes to make sure the object is a "widget " or a "sprocket" or an anything before routing to it , and eventually validating against it

After taking a look at http://guides.rubyonrails.org/routing.html#advanced-constraints, I have the following on my routes.rb

class WidgetssConstraint
  def initialize
    @widgets = Widget.all
  end

  def matches?(request)
    @widgets.include?(request.widget_slug)

  end
end


FunParts::Application.routes.draw do
  namespace 'admin' do
    resources :widgets
    resources :sprockets
    root 'widgets#index'
  end

  get "*widget_slug" => "widgets#show" , :constraints => WidgetsConstraint.new
end

and my widgets controller looks like this

class WidgetsController < ApplicationController
  layout 'public'

  def show
    @widget= Widget.where(slug: params[:widget_slug]).first

    if @widget.present?
      render :show
    else
      render :file => "#{Rails.root}/public/404", :layout => false, status: 404
    end
  end
end

I get the error below

undefined method `widget_slug' for ActionDispatch::Request:0x56ea700

Extracted source (around line #7):

  def matches?(request)
    @trucks.include?(request.widget_slug)

  end
end

Request

Parameters:

{"widget_slug"=>"ultra/lifter"}

Answer 1

The problem is this line:

    @widgets.include?(request.widget_slug)

You're calling widget_slug on the request object, which knows nothing about widgets. Here are the docs for Request: http://api.rubyonrails.org/classes/ActionDispatch/Request.html

I'd suggest moving this functionality to the widget controller. It's simple enough to do the validation in your show action rather than create a Constraint, especially one that fetches all widgets on every request.