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https://github.com/crate/activerecord-crate-adapter

Ruby on Rails ActiveRecord adapter for CrateDB
https://github.com/crate/activerecord-crate-adapter

activerecord cratedb database rails ruby ruby-gem ruby-library ruby-on-rails sql sql-database

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Ruby on Rails ActiveRecord adapter for CrateDB

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## About



The Ruby on Rails ActiveRecord adapter for [CrateDB],

using the [crate_ruby] driver with HTTP connectivity.



**Note:** The `activerecord-crate-adapter` currently only works with Rails 4.1.x.



## Installation



Add this line to your application's `Gemfile`:



    gem 'activerecord-crate-adapter'



And then execute:



    $ bundle



Or install it yourself as:



    $ gem install activerecord-crate-adapter



## Usage



When using Rails update your database.yml



     development:

       adapter: crate

       host: 127.0.0.1

       port: 4200



CrateDB doesn't come with an autoincrement feature for your model ids. So you need to set

it yourself. One way is to use `SecureRandom.uuid`, if you think there is a better one,

please add an issue, so we can discuss.



    class Post < ActiveRecord::Base



      before_validation :set_id, on: :create



      private



      def set_id

        self.id = SecureRandom.uuid

      end



    end



## Special data types



### Array

You can simply create Array columns by specifying `t.array` and passing `array_type` when you create a migration.



    t.array :tags, array_type: :string

    t.array :votes, array_type: :integer

    t.array :bool_arr, array_type: :boolean



When you create an object just pass your Array directly



    Post.create!(title: 'Arrays are awesome', tags: %w(hot fresh), votes: [1,2])

    post = Post.where("'fresh' = ANY (tags)")



### Object

CrateDB allows you to define nested objects. I tried to make it as simply as possible to use and reuse existing AR functionality,

I therefore ask you to reuse the existing serialize functionality. `AR#serialize` allows you to define your own serialization

mechanism, and we simply reuse that for serializing an AR object. To get serialize working simply create `#dump` and `#load` methods

on the class that creates a literal statement that is then used in the SQL. Read up more in this [commit about array and object literals].



I tried to make your guys life easier and created a module that does this automatically for you. Simply make all attributes accessible

and assign it in the initializer. So a serialized class should look like this:



    require 'active_record/attribute_methods/crate_object'



    class Address

      attr_accessor :street, :city, :phones, :zip



      include CrateObject



      def initialize(opts)

        @street = opts[:street]

        @city = opts[:city]

        @phones = opts[:phones]

        @zip = opts[:zip]

      end



    end



Check out the `CrateObject` module if you need to write your own serializer.



Then in your model simply use `#serialize` to have objects working.



      class User < ActiveRecord::Base

        serialize :address, Address

      end



Note: I do not plan to support nested objects inside objects.



#### Object Migrations



In the migrations, you can create an object, specify the object behaviour 

`(strict|dynamic|ignored)`, and its schema.



    t.object :address, object_schema_behaviour: :strict,

                       object_schema: {street: :string, city: :string, phones: {array: :string}, zip: :integer}



## Migrations



Currently, adding and dropping indices is not support by CrateDB, see [issue #733].



    # not supported by CrateDB yet

    add_index :posts, :comment_count

    remove_index :posts, :comment_count



## Caveats



CrateDB is eventually consistent, that means if you create a record, and query

for it right away, it won't work (except queries for the primary key).



In this context, read more about the [`REFRESH TABLE`] statement.



## Tests



See [DEVELOP.md](DEVELOP.md).



## Contributing



If you think something is missing, either create a pull request

or log a new issue, so someone else can tackle it.

Please refer to [CONTRIBUTING.rst](CONTRIBUTING.rst) for further information.



## Maintainers



* [Crate.IO GmbH](https://crate.io)

* [Christoph Klocker](http://vedanova.com), [@corck](https://twitter.com/corck)



## License



This project is licensed under the [Apache License 2.0].



[Apache License 2.0]: https://github.com/crate/activerecord-crate-adapter/blob/master/LICENSE

[commit about array and object literals]: https://github.com/crate/crate/commit/16a3d4b3f2

[CrateDB]: https://github.com/crate/crate

[crate_ruby]: https://github.com/crate/crate_ruby

[issue #733]: https://github.com/crate/crate/issues/733

[`REFRESH TABLE`]: https://crate.io/docs/crate/reference/en/latest/general/dql/refresh.html