Acts As Filter is an ActiveRecord filtering plugin based on named_scopes

Installation

In your model class your declare "acts_as_filter" and you now have an extra class method: find_by_filter

find_by_filter accepts a hash of scope names and values, and chains them into parametised scope calls.

If the model has a named_scope that matches the provided name, this is called. If no named_scope is found, an anonymous scopes is created.

For example: Given the following model definitions

  class Document < ActiveRecord::Base
    acts_as_filter
    belongs_to :author

    named_scope :author_name,
                lambda { |*args| {
                  :include => "author",
                  :conditions => ["authors.name = ?", args.first]
                }}

  end

  class Author < ActiveRecord::Base
    has_many :documents
  end

We can now from our controller accept incoming parameters and pass them to find_by_filter:

  # uses the declared "author_name" scope
  options = {:author_name => "toby"}
  documents = Document.find_by_filter(options)

  # creates an anonymous scope on the "name" column
  options = {:name => "document_1"}
  documents = Document.find_by_filter(options)

  # combines the two above scopes into a single chained call
  options = {:author_name => "toby", :name => "document_1"}
  documents = Document.find_by_filter(options)

See? Awesome.