:include:QUICKLINKS
 
= FAQ
 
=== So where's my :id column?
 
DataMapper will NOT create an auto-incrementing <tt>:id</tt> key for you 
automatically, so you'll need to either explicitly create one with
 
  property :id, Serial
 
You can choose to use a natural key by doing
 
  property :slug, String, :key => true
 
Remember, DataMapper supports multiple keys ("composite keys"), so if your
model has two or more keys, no big deal
 
  property :store_id,   Integer, :key => true
  property :invoice_id, Integer, :key => true
 
=== How do I make a model paranoid?
 
Create a property and make it a ParanoidDateTime or ParanoidBoolean type.
 
  property :deleted_at, ParanoidDateTime
  property :deleted, ParanoidBoolean
 
All of your calls to <tt>##all()</tt>, <tt>##first()</tt> will be scoped 
with <tt>:deleted_at => nil</tt> or <tt>:deleted => false</tt>. Plus, 
you won't see deleted objects in your associations.
 
=== Does DataMapper do Single Table Inheritance?
 
This is what the Discriminator data-type is for:
 
  class Person
    include DataMapper::Resource
    property :id, Serial
    property :type, Discriminator ## other shared properties here
  end
 
  class Salesperson < Person; end
 
You can claim a column to have the type <tt>Discriminator</tt> and DataMapper will
automatically drop the class name of the inherited classes into that field of
the data-store.
 
=== How do I run my own commands?
 
  repository.adapter.query("select * from users where clue > 0")
  repository(:integration).adapter.query("select * from users where clue > 0")
 
This does not return any Users (har har), but rather Struct's that will quack
like Users. They'll be read-only as well.
 
<tt>repository.adapter.query</tt> shouldn't be used if you aren't expecting a result set
back.  If you want to just execute something against the database, use
<tt>repository.adapter.execute</tt> instead.
 
 
=== Can I get an query log of what DataMapper is issuing?
 
Yup, to set this up, do:
 
  DataMapper::Logger.new(STDOUT, 0)
 
Incidentally, if you'd like to send a message into the DataMapper logger, do:
 
  DataMapper.logger.debug { "something" }
  DataMapper.logger.info { "something" }
  DataMapper.logger.warn { "something" }
  DataMapper.logger.error { "something" }
  DataMapper.logger.fatal { "something" }