cheat sheets.

--- datamapper version 7	Sun Jul 27 20:49:59 +0000 2008
+++ datamapper version 10	Mon Aug 11 04:15:08 +0000 2008
@@ -1,107 +1,116 @@
 DataMapper, the ruby object relational mapper
   website:  http://www.datamapper.org
   git:      git://github.com/sam/dm-core.git
   mail:     http://groups.google.com/group/datamapper
   wiki:     http://github.com/sam/dm-core/wikis
+  now:      http://www.twitter.com/datamapper
 
 Setting up a Connection
   DataMapper.setup(:default, "adapter://user:password@hostname/dbname")
   supported adapters: mysql, sqlite3, postgres, sqlite3::memory:
   additional adapters are in dm-more, (couchdb, rest, imap, file, saleforce...)
 
 Creating a Model (with properties)
   class Zoo
     include DataMapper::Resource
     property :id, Serial
   end
 
 
 Properties
   property :id,   Serial               # auto-incrementing PK
   property :name, String, :key => true # natural key
     # you must specify >= 1 key, CPK support 100%
 
   # available data-types
   property :description, Text # (lazy by default)
   property :created_at,  DateTime
   property :open,        Boolean
   property :admission,   BigDecimal
-  
+
   # require dm-types for Csv, Enum, EpochTime, FilePath, Flag, 
   #  IPAddress, URI, Yaml
 
 Property Options (pass as hash)
   :default, :nullable, :field (column name), :size, :length, :format,
   :index, :unique_index, :ordinal, :auto_validate, :precision,
   :scale, :accessor, :reader, :writer, :lazy
 
 
 Finders
   Zoo.get(PK_HERE)
   Zoo.first({see_below})
   Zoo.all({see_below})
 
 Finder Options (pass as hash)
   :conditions => ["property = ? and property = ?", 'value', 'value']
   :conditions => {:property => 'value', ...}
-  :property => 'ZooNameHere'
+  :property => 'ZooNameHere' 
+     # any non-standard key => value pair is assumed a condition if not 
+     # otherwise recognized
   :property.lte => 12.00  # <=
            .gte           # >=
            .gt            # >
            .lt            # <
            .not           # NOT =
            .like          # LIKE
            .in            # IN ()
   'class.property' => 'value'
-  Class.relationship.property =&gt; 'value'
+  Class.relationship.property =&gt; 'value' # will automatically issue JOINS
 
 Finder Gotcha
   :order => [:created_at.desc, ...] # descending sort
                         .asc        # ascending
 
 
 Associations
   has 1                    # has_one
   has n                    # has_many
   belongs_to :things   
   has n, :things, :through => :more_things
   has n, :things, :through => Resource # has_and_belongs_to_many
-  
+
 Association Options
   (any Finder Options)
   :class_name => 'ClassNameHere'
   :order => [:property.desc]
   :child_key => [:property, ...]
   :through => :other_association
-  
 
+
 Validations (require 'dm-validations')
   validates_present     :title
   validates_is_number   :rating
   validates_format      :email, :as => :email_address
   validates_length      :summary, :in => (1..100)
   validates_is_unique   :slug
-  validates_method (do...end, :method_name)
+  validates_with_method (do...end, :method_name)
 
 
-Callbacks
+Callbacks AKA &quot;Hooks&quot;
   Object-level
     before :method_name, (do...end, :another_method_name)
     after  :method_name, (do...end, :another_method_name)
   Class-level
     before_class_method :method_name, (do...end, :another_method_name)
     after_class_method  :method_name, (do...end, :another_method_name)
 
+Callbacks Gotcha
+  Hooks act on 'self' and aren't passed an arguement
+  'self' for object-level hooks are the instance
+  'self' for class-level hooks are the class itself
 
 Misc. Stuff & Gotchas
   Single Table Inheritance
     property :type, Discriminator # then inherit from this model
-  
+
   Paranoia
     property :deleted_at, ParanoidDateTime
     property :deleted,    ParanoidBoolean
-  
+
   Multiple DB Connections
     DataMapper.setup(:external, "adapter://username:password@hostname/dbname")
     repository(:external) do...end
+    Association: has n, :things, :repository =&gt; repository(:external)
+    Finder: Thing.all(:repository =&gt; repository(:external))