WeakParameters 
Validates params in your controller.
Installation
gem "weak_parameters"
Usage
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
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
Available validators
- any
- array
- float
- hash
- integer
- string
- boolean (= 0, 1, false, true)
- file
- object
- list
Available options
- required
- only
- except
- handler
- strong
Tips
WeakParameters.stats returns its validation metadata, and this is useful for auto-generating API documents. With autodoc, you can auto-generate API documents with params information.