gem "weak_parameters"

class ApplicationController < ActionController::Base
  protect_from_forgery

  respond_to :json

  rescue_from WeakParameters::ValidationError do
    head 400
  end
end

# WeakParameters provides `validates` class method to define validations.
class RecipesController < ApplicationController
  validates :create do
    string :name, required: true, except: ["charlie", "dave"], strong: true
    integer :type, only: 1..3, strong: true
    string :quantity do |value|
      value =~ /\A\d+(?:\.\d+)g\z/
    end
    date :date, format: ["%Y/%m/%d", "%Y.%m.%d"]
    time :time, format: "%Y/%m/%d %H:%M:%S"
  end

  def create
    # pass the only parameters with strong option. like strong parameters.
    respond_with Recipe.create(permitted_params)
  end
end

irb(main):001:0> app.accept = "application/json"
=> "application/json"
irb(main):002:0> app.post "/recipes", name: "alice", type: 1
=> 201
irb(main):003:0> app.post "/recipes", name: "alice"
=> 201
irb(main):004:0> app.post "/recipes", type: 1
=> 400
irb(main):005:0> app.post "/recipes", name: "alice", type: "bob"
=> 400