= ParamChecker

ParamChecker is a small library for validation and parsing of user provided parameters. It is a handy way to check GET/POST params in Ruby webframeworks (like Rails or Sinatra).

== Installation

  gem install param_checker

or add ParamChecker to your Gemfile

  gem 'param_checker'

and afterwards (when using the Gemfile) execute

  bundle install

== Usage

Include the ParamChecker module where ever you like. I usually put it into my Rails +ApplicationController.rb+

  class ApplicationController < ActionController::Base
    include ParamChecker
  end

You can then simply call +check_string_param(param_to_check, "my default", ["foo", "bar"])+ in every controller.

Instead of including the module you could also call all functions of the module directly.

  ParamChecker.check_string_param(param_to_check, "my default", ["foo", "bar"])

There are currently 5 supported functions:

* +check_integer_param(param, default, min, max)+
* +check_float_param(param, default, min, max)+
* +check_string_param(param, default, allowed)+
* +check_symbol_param(param, default, allowed)+
* +check_boolean_param(param, default)+

+param+ is always the string parameter to check. +default+ is a value that is returned when +param+ does not succeed the check.
+min+ and +max+ in +check_integer_param+ and +check_float_param+ are the minimum and maximum allowed values of param. Both +min+ and +max+ options are optional. If they are not provided then no range is checked at all.
+allowed+ in +check_string_param+ and +check_symbol_param+ represent the allowed values of +param+. They can be either a string (resp. a symbol for +check_symbol_param+), a regular expression, or an array of strings (resp. symbols for +check_symbol_param+).
+check_boolean_param+ evaluates "1" or "true" string as true and "0" or "false" string to false.
All functions return the parsed and type cast value (check_integer_param returns an integer, check_symbol_param returns a symbol, and so on).

== Examples

Below are some simple examples how I use those function in my controllers.

  # +max+ is not provided in this case. I just want to ensure that page is bigger than 1 and otherwise return 1.
  page = check_integer_param(params[:page], 1, 1)

  # Returns "name" if params[:field] is not "name" or "address"
  field = check_string_param(params[:field], "name", ["name", "address"])

  # Return the boolean if params[:accepted] is a valid boolean representation, and the default false otherwise.
  accepted = check_boolean_param(params[:accepted], false)

== Testing

ParamChecker uses RSpec for testing and has a rake task for executing the provided specs

  rake spec

Copyright © 2010-2011 Kai Schlamp (http://www.medihack.org), released under the MIT license