Documentation

API

The API for the current gem release.

Why DataMapper?

If you haven’t read this yet, you should, right now!

Getting Started

A whirlwind tour of DM. This is the place to start if you haven’t used the library before.

Common installation issues

Troubleshooting installation, with instructions for specific platforms.

Properties

Properties declared in your model map to the fields in the database.

Creating, Saving and Destroying Records

Obviously you’re going to be doing a lot of this :)

Validations

Auto-validations, manual validations, contextual validations

Finding and Counting Records

There are lots of nice ways to find records.

Associations

Models can be associated to each other in various ways using the has keyword

Hooks

Hooks, AKA Callbacks, allow you to “advise other methods” by running methods before or after calling other methods.

Misc. Features

Paranoia, Single Table Inheritance, and Multiple Repositories.

Documentarians Wanted!

Want to help DataMapper, but don’t know where to start? A great way to contribute is to help out in the documentation effort.

Documentation Style

DataMapper uses the YARD standard for RDoc documentation. Here’s a brief sample from the internals of DM-Core:

 1 ##
 2 # Setups up a connection to a data-store
 3 #
 4 # @param name<Symbol> a name for the context, defaults to :default
 5 # @param uri_or_options<Hash{Symbol => String}, Addressable::URI, String>
 6 #   connection information
 7 #
 8 # @return <Repository> the resulting setup repository
 9 #
10 # @raise <ArgumentError> "+name+ must be a Symbol, but was..." indicates that
11 #   an invalid argument was passed for name<Symbol>
12 # @raise <ArgumentError> "+uri_or_options+ must be a Hash, URI or String, but was..."
13 #   indicates that connection information could not be gleaned from the given
14 #   uri_or_options<Hash, Addressable::URI, String>
15 # -
16 # @api public
17 def self.setup(name, uri_or_options)
18   raise ArgumentError, "+name+ must be a Symbol, but was #{name.class}", caller unless Symbol === name
19   ...

For more information about the YARD documentation style, see lsegal’s YARD repo on github.com.