Rack::Params

Rack::Request.params validation and type coercion, on Rack.

Usage

Documentation

1. Include Rack::Params to get the .validator, #validate and #validate! methods.
2. Call .validator(name, options = {}, &code) to register a named validator for use later.
3. Call #validate(name = nil, params = request.params, options = {}, &code) to build a new result, with the results of validation and coercion.
4. The blocks passed to the validation methods run in the context of HashContext and ArrayContext, which is where the coercion methods are defined.

Example

# NOTE (to self) - if this changes, update `readme_spec.rb`

class SomeExampleApp
  include Rack::Params

  # create named validators that can be run at any time
  
  validator :document do
    param :id,      Integer,  required: true
    param :title,   String,   required: true
    param :created, DateTime
    
    param :tags, Array do
      every :symbol
    end
    
    param :content, Hash, required: true do
      param :header, String
      param :body,   String, required: true
    end
  end
  
  # run pre-defined or ad-hoc transforms on some hash
  # only keys in the validator blocks are copied, see #splat

  def call(env)
    request = Rack::Request.new(env)
    
    params = request.params
    params = validate(request.params, :document)
    if params.valid?
      assert params["id"].is_a? Integer
      assert (not params["content"]["body"].nil?)
    else
      assert params.errors.length > 0
      assert params.invalid?
    end

    # or
    params = { "flag" => "f", "some" => "other key", "and" => "one more" }
    params = validate(params) do
      param :flag,  :boolean, required: true
      splat :rest
    end
    
    if params.valid?
      assert [true, false].include?(params["flag"])
      assert (["some", "and"] - params["rest"]).empty?
    end

  end
end

# if you're using a framework which provides `request` as a getter method
# include the connector, which provides a `#params` override, and allows
# defaulting to request.params in validate calls

class FancyApp < Nancy::Base
  include Rack::Params::Connect

  validator :check do
    :id, Integer
  end
  
  get "/" do
    validate :check

    if params.valid?
      assert params["id"].is_a? Integer
    else
      assert params.errors.length > 0
      assert params.invalid?
    end
    
    "magic 8-ball, how's my params? << uncertan. >>"
  end

  get "/blow-up-on-failure" do
    validate! :check
    assert params.valid?

    "if I'm going down, I'm taking you all with me."
  end
end

Installation

Add this line to your application's Gemfile:

gem 'rack-params'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rack-params

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/lygaret/rack-params.

License

The gem is available as open source under the terms of the MIT License.

Authors

• Jon Raphaelson - https://accidental.cc
• Based heavily on mattt/sinatra-param, though diverging significantly in ways.