ActiveRecord has a limitation for finder support. In order to extend it
you have to either muck up ActiveRecord, a database adapter or you end
up creating an extension that aliases all of the find, sanitize_sql,
attribute_conditions, etc. methods.
I've been working the past few weeks on pulling out finder support into
Extensions, which decouples it from AR core code, and allows there to be
more flexibility with finder support.
The whole idea of moving finder support into a set of command extensions
is to implement the Chain Of Responsibility[0] design pattern for
processing find conditions that are given as a Hash.
I briefly posted on this the other week[1] with an example of how I make
Ranges work.
The benefits I see of this are the following:
- decouple finder support in AR from AR core (promote loose coupling)
- allows developers who want to extend AR finder support to do so
without redefining parts of AR core
- allows developers to use any core/stdlib class in Ruby or any user
defined class to aide in special searching support
- lowers the barrier for developers who want to write extensions for
finders
- allows developers to write finder extensions to enhance support for
more database vendor functionality.
- simplifies the process for enhancing finder support in AR which
reduces the chance that someone will inadvertently break other AR
functionality
Some examples of this are allowing things like:
Model.find( :all, :conditions=>{ :name=>'Zach' } )
Model.find( :all, :conditions=>{ :name=> [ 'Zach', 'John', Doug' ] } )
Model.find( :all, :conditions=>{ :name=> /Zach|John|Doug/ } )
Model.find( :all, :conditions=>{ :number=> (0..100) } )
Model.find(:all,:conditions=>{:created_on=>(Date.today..Date.today-30 })
Model.find( :all, :conditions=>{ :description_contains=>'Good' } )
Model.find( :all, :conditions=>{ :description_starts_with=>'Good' } )
Model.find( :all, :conditions=>{ :description=>UserCreatedObject.new })
I am not advocating that all enhancements to finder support would go in
core, but if the Extensions implemented using the Chain Of
Responsibility pattern is in core it will allow developers to enrich
plugins/extensions for Oracle, MySQL or PostgreSQL (or any other db
adapter) support with a lower barrier of entry, and lower chance of
breaking any other part of AR.
I'm a MySQL guy right now, slowly picking up PostgreSQL. I'm looking for
people who are PostgreSQL, MS SQL, Oracle, etc users who would be
interested in setting up automated (or manual) testing to help get all
of AR's tests passing with this functionality, so this can be offered as
a patch to AR.
Zach
http://www.continuousthinking.com
[0] http://en.wikipedia.org/wiki/Chain-of-responsibility_pattern
[1]
http://www.continuousthinking.com/are/finder-extensions-and-mysql-fulltext-indexes
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