ActiveRecord: mapping column names when using legacy schemata

rubyonrails-talk
1

I have an ActiveRecord question...

I have a legacy MySQL database with a weird naming convention - all table and column names have a prefix '_' , which is annoying, and some of the column names are plain misnomers.

I would like to apply a pre-defined mapping between MySQL column names and method names to be used in the Ruby class, without having the underlying column names being visible anymore.

How can I pre-define a static mapping of all (legacy) column names to new Class method names?

e.g.: given legacy schema:

Table _fix has columns:    _job    _ change    _date    _effect

When defining the Ruby class, I'd like to do something like this:

class Fix < ActiveRecord::Base    self.table_name = "_fix"    use_mapping ( # imaginary construct..        :_job => "job_id",        :_change => "change_id" ,        :_date => "date" ,        :_effect => "status")

   self.primary_key = "job_id" # no more reference to _job column end

and want to access it like this:

   Fix.find( id ).status = "partial fix" # should update the column _effect in table _fix

   # and i want to see this :slight_smile:

   Fix.find( id )._job     NoMethodError: undefined method '_job' for ...    Fix.find( id )._effect     NoMethodError: undefined method '_effect' for ...

The schema of the underlying legacy database should not be modified in any way.

Is there a way to do this? Is there a way to code a helper method for ActiveRecord::Base which does the above mapping?

thanks

   Tilo