find_by_param

find_by_param helps you dealing with permalinks and finding objects by our permalink value

class Post < ActiveRecord:Base
  make_permalink :with => :title
end

now you can do

Post.find_by_param(...)

If you have a permalink-column find_by_param saves the permalink there and uses that otherwise it just uses the provided attribute.

Installation

As gem from gemcutter:

% gem install find_by_param

Building your own

% rake gemspec
% rake install

As Rails plugin

% script/plugin install git://github.com/bumi/find_by_param.git

Examples

Configuration

make_permalink :with => :login
make_permalink :with => :title, :prepend_id => true
make_permalink :with => :name, :forbidden => %w(new edit)

Client code

Post.create(:title => "hey ho let's go!").to_param #=> "hey-ho-lets-go" 
          # ... to_param is the method Rails calls to create the URL values

Post.find_by_param("hey-ho-lets-go") #=> <Post>

Post.find_by_param("is-not-there")   #=> nil
Post.find_by_param!("is-not-there")  #=> raises ActiveRecord::RecordNotFound

Basic Documentation

Options for make_permalink

The following options may be used, when configuring the permalink generation with make_permalink.

• :with (required)

  The attribute that should be used as permalink

• :field

  The name of your permalink column. make_permalink first checks if there is a column.

• :prepend_id => [true|false]

  Do you want to prepend the ID to the permalink? for URLs like: posts/123-my-post-title - find_by_param uses the ID column to search.

• :escape => [true|false]

  Do you want to escape the permalink value? (strip chars like öä?&) - actually you must do that

• :forbidden => [Regexp|String|Array of Strings]

  Define which values should be forbidden. This is useful when combining user defined values to generate permalinks in combination with restful routing. Make sure, especially in the case of a Regexp argument, that values may become valid by adding or incrementing a trailing integer.

Class methods provided by find_by_param

The following methods are added as public methods to all classes containing a permalink field.

• find_by_param(id)

  Look up a value by its permalink value, returns matching instance or nil, if none is found.

• find_by_param!(id)

  Look up a value by its permalink value, returns matching instance or raises ActiveRecord::RecordNotFound, if none is found.

Issues

• Alex Sharp (http://github.com/ajsharp) pointed to an issue with STI. Better call make_permalink in every child class and not only in the parent class..
• write nice docs
• write nicer tests

Copyright (c) 2007 [Michael Bumann - Railslove.com], released under the MIT license