Keyword Search

Description

Generic library to parse GMail-style search strings for keyword/value pairs; supports definition of valid keywords and handling of quoted values.

Requirements

None.

Features

The library features a very simple, easy-to-use API.

• Define handlers for supported keywords with blocks
• Define the default keyword (values not part of a keyword/value pair)
• Handle negation

Please see the example provided below.

Synopsis

Here's an example using ActiveRecord (though the library is generic, and can be used for any Ruby project). The library isn't limited to search terms, as shown in this example; how you use it is up to you.

First, let's build up some variables we'll be populating for a SQL query.

clauses = []
arguments = []

Now let's set an example string to parse. Presumably you'd get this from a form (ie, params[:terms]) or some other form of input.

terms = 'account has:attachment since:2006-12-03 -description:crazy'

Now let's do the search, defining the handlers to deal with each keyword.

KeywordSearch.search(terms) do |with|

  # This sets the keyword handler for bare words in the string,
  # ie "account" in our example search terms
  with.default_keyword :title

  # Here's what we do when we encounter a "title" keyword
  with.keyword :title do |values|
    clauses << "title like ?"
    arguments << "%#{values.join(' ')}%"
  end

  # For "has," we check the value provided (and only support "attachment")
  with.keyword :has do |values|
    clauses << 'has_attachment = true' if values.include?('attachment')
  end

  # Here we do some date parsing
  with.keyword :since do |values|
    date = Date.parse(values.first) # only support one
    clauses << 'created_on >= ?'
    arguments << date.to_s
  end

  # If a second parameter is defined for a block, you can handle negation.
  # In this example, we don't want results whose description includes
  # the word "crazy"
  with.keyword :description do |values, positive|
    clauses << "description #{'not' unless positive} like ?"
    arguments << "%#{values.join(' ')}%"
  end

end

Immediately after the block is defined, the string is parsed and handlers fire. Due to the magic of closures, we now have populated variables we can use to build a real SQL query.

query = clauses.map { |c| "(#{c})" }.join(' AND ')
conditions = [query, *arguments]
results = Message.all(:conditions => conditions)

Installation

keyword_search is only released on gemcutter. To install, you can setup gemcutter as your default gem source.

$ gem install gemcutter
$ gem tumble

Then you can install it:

$ gem install keyword_search

You can also just get it in one line:

$ gem install keyword_search -s http://gemcutter.org

License

(The MIT License)

Copyright (c) 2007 Bruce Williams

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Legal Notes

GMail is copyright Google, Inc.