ResourceFinder is a simple Rails gem that finds resource for controller from request parameters. It lets you write less codes and eradicates repeat resource finding codes completely in every controller.

Generally, when we need to find the resource in controller for actions, we can do like this:

class UsersController < ApplicationController

  def show
    @user = User.find(params[:id])
  end

  def edit
    @user = User.find(params[:id])
  end

  def update
    @user = User.find(params[:id])
  end

  def destroy
    @user = User.find(params[:id])
  end

end

Or, we always use before_action makes it looks better:

class UsersController < ApplicationController
  before_action :find_user, only: [:show, :edit, :update, :destroy]

  def show
  end

  def edit
  end

  def update
  end

  def destroy
  end

  private

  def find_user
    @user = User.find(params[:id])
  end
end

What we done above can solve the repeate codes problem in a single controller, but there will be a lots of controllers in Rails project, we need to define a lots of find_xxx methods in its controller. So ResourceFinder is designed to solve this problem.

Add the gem to your Gemfile:

gem 'resource_finder'

Install the gem with bundler:

bundle install

To add ResourceFinder in your Rails project, first put it included in your ApplicationController.

class ApplicationController
  include ResourceFinder
end

And then you can use it in every controllers which inherited from ApplicationController.

class UsersController < ApplicationController
  findable :user

  def destroy
    @user.destroy # now you can just call @user here
  end
end

When nested resources, posts belongs to user.

class PostsController < ApplicationController
  findable :user
  findable :post, scope: :user
end

Basicly, you can set only or except options like before_action, basides there are some useful keys for options:

• model
• query
• in
• of
• scope
• lazy
• silent

By default, ResourceFinder will detect model based on the object your set by findable.

findable :customer # default Customer model
findable :customer, model: User

By default, ResourceFinder gets the query content by query name object_id in parameters.

class PostsController < ApplicationController
  findable :user # params[:user_id]
end

But if the object model is same as the model deduced from current controller name. ResourceFinder will use id to get query content from parameters.

class UsersController < ApplicationController
  findable :user # params[:id]
  findable :customer, model: User # params[:id]
end

You can also pass a lambda/array/string/symbol to query options.

findable :user, query: :uuid # params[:uuid]
findable :user, query: [:user, :id] # params[:user][:id]
findable :user, query: -> (params) { your_decoder params[:encode_user_id] }

By default, ResourceFinder uses id to query.

findable :user # query in column: [:id]
findable :user, in: :uuid # query in column: [:uuid]
findable :user, in: [:id, :uuid] # query in columns: [:id, :uuid]

For nested resources, maybe you want to limit the resource.

findable :user
findable :post, scope: :user # make sure @post is one of @user.posts

findable :user
findable :city, of: :user # same as: @city = user.city

Sometimes, you prefer to improve performance, lazy: true can let ResourceFinder be lazy load, also, there will be no any instance variables generated any more.

class UsersController < ApplicationController
  findable :user, lazy: true

  def show
    user = findable(:user)
    render json: user
  end
end

By default, ResourceFinder will be allowed to raise error during source finding. For example: RecordNotFound. You can set silent: true to prevent error raised.

class UsersController < ApplicationController
  findable :user, silent: true

  def show
    # if user record not found
    # @user will be eq: nil
  end
end

Released under the MIT license. See LICENSE file for details.