Ruby XCDM
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README.md

ruby-xcdm

This is a tool for generating the same xcdatamodeld files that XCode does when designing a datamodel for Core Data. It is written in pure ruby, but it will be of particular interest to RubyMotion developers. It offers the essential features that XCode does, plus a text-based workflow and some niceties, like automatic inverse relationships.

Installation

Add this line to your application's Gemfile:

  gem 'ruby-xcdm'

And then execute:

  $ bundle

Or install it yourself as:

  $ gem install ruby-xcdm

Usage (RubyMotion)

  1. Make a directory called "schemas" inside your RubyMotion project
  2. Create one schema version per file within the directory
  3. To build the schema, run rake schema:build

If you want to build the schema every time you run the simulator, add this to your Rakefile:

task :"build:simulator" => :"schema:build"

Usage (Plain Ruby)

  1. Make a directory to hold your schemas (a.k.a. data model in XCode parlance)
  2. Create one schema version per file within the directory
  3. Run the command to generate a datamodel:
  xcdm MyApplicationName schemadir datamodeldestdir

Schema File Format

Here's a sample schema file:

  schema "001" do

    entity "Article" do

      string    :body,        optional: false
      integer32 :length
      boolean   :published,   default: false
      datetime  :publishedAt, default: false
      string    :title,       optional: false

      belongs_to :author
    end

    entity "Author" do
      float :fee
      string :name, optional: false
      has_many :articles 
    end

  end

All the built-in data types are supported:

  • integer16
  • integer32
  • integer64
  • decimal
  • double
  • float
  • string
  • boolean
  • datetime
  • binary
  • transformable

Inverse relationships are generated automatically. If the inverse relationship cannot be derived from the association name, you can use the :inverse option:

  entity "Game" do
    belongs_to :away_team, inverse: "Team.away_games"
    belongs_to :home_team, inverse: "Team.home_games"
  end

  entity "Team" do
    has_many :away_games, inverse: "Game.away_team"
    has_many :home_games, inverse: "Game.home_team"
  end

Many-to-many relationships are supported via the :plural_inverse option:

  entity "Person" do
    has_many :threads, plural_inverse: true
  end

  entity "Thread" do
    has_many :people, plural_inverse: true
  end

In this mode, Core Data will automatically create a relation table behind the scenes. If you want more control, you can make the intermediate table yourself:

  entity "Person" do
    has_many :postings
  end

  entity "Thread" do
    has_many :postings
  end

  entity "Posting" do
    belongs_to :person
    belongs_to :thread

    datetime :joined_at
  end

Core data has no equivalent of :through in ActiveRecord, so you'll need to handle that relation yourself.

If you need to set some of the more esoteric options on properties or relationships, you can include the raw parameters from NSEntityDescription and NSAttributeDescription, like renamingIdentifier or defaultValueString.

Versioning

To create new versions, simply copy the old version, increase the version string (the last one in sort order is always interpreted to be the current version) and make your changes. So long as they conform to the automatic versioning rules, everything should work seamlessly.

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request