Nitron

Introduction

Nitron Data is an opinionated CoreData wrapper for RubyMotion extracted from https://github.com/mattgreen/nitron/

Installation

Add the following line to your Gemfile:

gem "nitron-data", :git => "git://github.com/juanger/nitron_data.git"

If you haven't already, update your Rakefile to use Bundler. Insert the following immediately before Motion::Project::App.setup:

require 'rubygems'
require 'bundler'

Bundler.require

Then, update your bundle:

bundle

And build your application:

rake

Features

Beginnings of a CoreData model abstraction uses XCode's data modeling tools with an ActiveRecord-like syntax
Migrations rake tasks to generate data models

Example

A Task model

class Task < NitronData::Model
  attribute :title, String
  attribute :created_at, Time
  attribute :priority, "Decimal"
end

Then create your xcdatamodel file with:

rake dm:migrate

CoreData ActiveRecord Support

Nitron offers lots of your favorite ActiveRecord features for data manipulation and searching, including the following methods.

# Querying Tasks

Task.all # Array of tasks

Task.pluck(:assignee_id) # returns array of non-distinct values
Task.uniq.pluck(:assignee_id) # now the array of id values is distinct

Task.first # First task or nil
Task.first! # First task or Nitron::RecordNotFound exception

Task.limit(1) # returns one task
Task.offset(5).limit(1) # grab the 6th task, as an array with one item in it
Task.where("title contains[cd] ?", "some") # grab all tasks with the title containing "some", case insensitive
Task.where("title contains[cd] ?", "some").count # db call to count the objects matching the conditions

Task.count # number of tasks in the system

Task.order("title", ascending: false) # Tasks order in reverse alphabetical order on title attribute

Task.count_by("title") # groups by column and returns count for each value

# Overriding existing query
scope = Task.where("status = ?", :open)
scope.except(:where).where("status = ?", :closed) # realized I really wanted closed items
scope.order(...).except(:order)
scope.limit(...).except(:limit)

# Daisy Chaining
Task.where(...).order(...).where(...).offset(10).limit(5).count # Yep, this works!
Task.where(...).order(...).all # array of the results

# Dynamic Finders
Task.find_by_status :open # returns the first task with a status of open, or nil
Task.find_all_by_status :open # returns array containing Tasks matching that status

# Creating tasks
Task.create assignee_id: 1, title: "some title" # runs validations, saves object into the default context if validations pass
Task.create! # Nitron::RecordNotSaved thrown if validations fail
Task.new # creates a new Task object, outside of a NSManagedObjectContext, optionally takes attributes

task = Task.new
task.save # will save, true if successful, false if failed
task.save! # will throw Nitron::RecordNotSaved if failed, contains errors object for validation messages

Caveats

Data binding doesn't use KVO presently. This is already in the works.
CoreData needs support for relationships.

License

Nitron is released under the MIT license:

http://www.opensource.org/licenses/MIT