A safe, dynamic way of searching and filtering your ActiveRecord models
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DynamicSifter is a safe way to simplify your search-and-sieve (search-and-filter) type searches in your ActiveRecord classes.

DynamicSifter takes advantage of named_scopes and uses them as filters for your searches.

Key features:

  • Takes the same arguments as any ActiveRecord#find call
  • Allows you to chain filters together

New in 0.2.2

  • Can now use filters that take lambda methods
  • Update README.textile to be more correct


You can add DynamicSifter to any application that uses ActiveRecord >= 2.1.0. You can add it to a Rails application by doing the following:

git submodule add git://github.com/jkatz/dynamic_sifter.git vendor/plugins/dynamic_sifter


To illustrate how to use DynamicSifter, let us use this example class:

class Book < ActiveRecord::Base named_scope :in_stock, :conditions => [‘quantity > 0’] named_scope :history, :conditions => { :genre => ‘history’ } named_scope :paperback, :conditions => { :paperback => true } named_scope :author => lambda { |author_name| :conditions => [‘author = ?’, author_name] }

  1. end

Let us say we have a form on our application that allows us to search for books with various attributes. We want to be able to get all the results in one-line of code, without worrying about writing complex boolean statements to apply the correct filters. To make a hard-coded, concrete example, to find all the history books that are in_stock, all we have to do is:

DynamicSifter.search(Book, :filters => [:history, :in_stock])

And DynamicSifter will returns our results just like any ActiveRecord::#find query!

To get more complex, let’s say I want to search for all the books by Yukio Mishima that are in stock and are in paperback. It would be silly to have a named scope for every author in our database! With DynamicSifter, we would do the following:

DynamicSifter.search(Book, :conditions => { :author => ‘Yukio Mishima’ }, :filters => [:in_stock, :paperback])

Let’s say we store our publisher contact information in a Publisher model. If we wanted to find the all the publishers for the books by Yukio Mishima that are paperback, in-stock, and have the list of publishers by in alphabetical order by name, we could do:

DynamicSifter.search(Book, :joins => :publisher, :conditions => { :author => ‘Yukio Mishima’ }, :select => ‘DISTINCT publishers.name’, :order => ‘publishers.name’, :filters => [:in_stock, :paper_back] )

Finally, we got smart and decided to put in a named_scope that let’s us filter by author. We want to filter by author and paperback, we can do:

DynamicSifter.search(Book, :filters => { :author => [‘Yukio Mishima’], :paperback => [] })


Why DynamicSifter?

DynamicSifter grew out of a need to find an easy way to chain search filters triggered by user inputs. An example of this is maintaining a list of contacts and sorting them by various information, e.g. breaking it down by name, particular attributes about the contacts, etc. Because I wanted to limit the amount of code in my Rails controllers for handling this, I wanted a dynamic, safe way to update my information without too much hassle. In one use of this, I actually have the users trigger the scopes, but the code in DynamicSifter ensures that the scope actually exists and that the user is not trying to do anything too funky.

Future Releases

  • Specs, specs, specs!
  • Better support for scopes on includes
  • Support for other ORMs?