cheat sheets.

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Cheat Sheet:
DataMapper, the ruby object relational mapper website: http://www.datamapper.org git: git://github.com/datamapper/dm-core.git mail: http://groups.google.com/group/datamapper now: http://www.twitter.com/datamapper irc://irc.freenode.net/datamapper irc://irc.freenode.net/dm-hacking before: http://irclogger.com/datamapper/ http://irclogger.com/dm-hacking/ bugs: http://datamapper.lighthouseapp.com/projects/20609-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_validation, :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' # 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 => '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_with_method (do...end, :method_name) Callbacks AKA "Hooks" 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 => repository(:external) Finder: Thing.all(:repository => repository(:external)) class Color include DataMapper::Resource DataMapper.setup(:colors_db, "sqlite3:path/to/colors.db") def self.default_repository_name :colors_db end property :name, String end

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