HashDB

HashDB is a minimal, in-memory, ActiveRecord like database library, backed by a Ruby Hash.

Installation

Gem releases are not done frequently as of now. I recommend installing through the git repository.

Add this line to your application's Gemfile:

gem 'hash_db', git: "https://github.com/utkarshkukreti/hash_db.git"

And then execute:

$ bundle

Or install it yourself as:

$ git clone https://github.com/utkarshkukreti/hash_db.git
$ cd hash_db
$ bundle install
$ rake install

Quickstart

(Complete usage instructions are below.)

require 'hash_db'

class Score
  include HashDB::Model
  keys :name, :points
end

score = Score.new name: "A", points: 10
score.save #= score.id == 1
Score.create name: "B", points: 11 #= id == 2
Score.create name: "C", points: 6 #= id == 3

Score.where(name: "B", points: 11).count #= 1
Score.where([:points, :>, 4], [:name, :=~, /a|b/i]).count #= 2
Score.find_by(:points, :>, 8).id #= 1

Usage

First, require HashDB.

require 'hash_db'

To make your class a HashDB model, just include HashDB::Model module in your class.

class Post
  include HashDB::Model
end

Defining attributes is as easy as calling keys, with the key names you want.

  keys :title, :content

HashDB will automatically create getters and setters for these keys, so you can now assign title and content to objects of the Post class.

post = Post.new
post.title = "Introducing HashDB"
post.content = "..."

Just as with ActiveRecord, you can also pass a Hash with key/value pairs to .new

# Same as above
post = Post.new title: "Introducing HashDB", content: "..."

To be able to query the model, objects must be saved, using .save.

post.save

This saves the object into Class.all Hash, with auto generated id key as the key, and object as the value.

Post.all == { 1 => post } #= true

Like ActiveRecord, .new and .save can be combined into just a .create call on the class.

Post.create title: "Second Post"
Post.all.count == 2 #= true

Querying

HashDB currently has just 2 query methods, .where, which can filter objects using key(s) = value(s), and also using custom method call, like :< and :>.

Let's take HN as an example. :)

class Item
  include HashDB::Model
  keys :url, :title, :points, :comment_count
end

Item.create url: "http://blog.heroku.com/archives/2011/7/12/matz_joins_heroku/",
            title: "Matz (creator of Ruby) joins Heroku",
            points: 569,
            comment_count: 79
Item.create url: "http://www.rubymotion.com/",
            title: "RubyMotion - Ruby for iOS",
            points: 466,
            comment_count: 248
Item.create url: "http://repl.it/",
            title: "Try Python, Ruby, Lua, Scheme, QBasic, Forth...",
            points: 379,
            comment_count: 80

You can query by key = value

Item.where(points: 569).count #= 1

by key = value pairs

Item.where(points: 569, comment_count: 79).count #= 1

by custom method call

Item.where(:points, :>, 400).count #= 2

and by custom method call pairs

Item.where([:points, :>, 400], [:title, :=~, /ios/i]).count #= 1

Associations