params_validator

A DSL for validating request parameters, raises exceptions when validation failed. Currently only supports Rails.

Current status is very much alpha, this gem is still under development and not intended to use in production applications.

Installation

Add this to your Gemfile and run bundle install

gem 'params_validator'

Usage

Basic usage:

class WelcomeController < ActionController::Base
  rescue_from ParamsValidator::InvalidParamsException do |exception|
    render :text => 'Error', :status => :bad_request
  end

  validate_params_for :index, { :count => { :_with => [:type_integer] } }
  def index
    @articles = Article.limit(params[:count])
  end
end

Validators

TypeInteger

validate_params_for :index, { :count => { :_with => [:type_integer] } }

Valid:

• count=1

Invalid:

• count=something
• count[]=1
• count[key]=value

TypeFloat

validate_params_for :index, { :position => { :_with => [:type_float] } }

Valid:

• position=0.42
• position=1

Invalid:

• position=something
• position[]=0.42
• position[key]=0.42

TypeString

validate_params_for :index, { :name => { :_with => [:type_string] } }

Valid:

• name=Jack
• name=1

Invalid:

• name[]=Jack
• name[key]=Jack

TypeHash

validate_params_for :index, { :options => { :_with => [:type_hash] } }

Valid:

• options[all]=true

Invalid:

• options=all
• options[]=all

TypeArray

validate_params_for :index, { :ids => { :_with => [:type_array] } }

Valid:

• ids[]=1

Invalid:

• ids=1
• ids[1]=true

Presence

validate_params_for :search, { :q => { :_with => [:presence] } }

Valid:

• q=term

Invalid:

• q=
• somethingelse=term

Validation errors

When validation of parameters fails, this gem is raising a ParamsValidator::InvalidParamsException error which contains an errors hash with further information.

The errors hash is modeled after the Rails model validation errors like this:

{
  :field_name => 'error description',
  :integer_field => 'is not of type integer'
}

As briefly described in the example at the beginning, the easiest way to rescue from validation errors is with a rescue_from block inside your controller, like this:

rescue_from ParamsValidator::InvalidParamsException do |exception|
  render :json => { :errors => exception.errors }, :status => :bad_request
end

Contributing to params_validator

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
• Fork the project.
• Start a feature/bugfix branch.
• Commit and push until you are happy with your contribution.
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright

Copyright (c) 2012 Christof Dorner. See LICENSE.txt for further details.