sequel-mysql_generated_columns

Sequel extension that adds support for MySQL generated columns (added first on MySQL 5.7.5).

When enabled, it allows passing an SQL expression with the option :as to #column and #add_column methods, inside DB#create_table and DB#alter_table blocks.

When used in a create_table block:

create_table(:triangles) do
  integer :a
  integer :b
  integer :c, :as => :sqrt.sql_function(:a*:a + :b*:b)
end

This will generate the following SQL statement:

CREATE TABLE `triangles` (
  `a` integer,
  `b` integer,
  `c` integer AS (sqrt(((`a` * `a`) + (`b` * `b`))))
)

In this example, after creating a table with a single JSON column, the next alter_table block:

create_table(:docs) do
  json :doc
end

alter_table(:docs) do
  add_column :id, Integer, :as => :json_extract.sql_function(:doc, '$.id'),
                           :stored => true,
                           :primary_key => true
end

will add a stored generated column with a primary key over the JSON object property id in from the JSON document stored in column doc:

CREATE TABLE `documents` (`doc` json)
ALTER TABLE `documents` ADD COLUMN `id` integer AS (json_extract(`doc`, '$.id')) STORED PRIMARY KEY

Add this line to your application's Gemfile:

gem 'sequel-mysql_generated_columns'

And then execute:

$ bundle

Or install it yourself as:

$ gem install sequel-mysql_generated_columns

To enable extension, call DB.extension :mysql_generated_columns.

Use #column or #add_column with an extra options :as => expr where expr is an SQL expression object or a string literal.

Possible options:

• :stored: Whether generated column will be STORED or VIRTUAL. By default it omits the STORED keyword, so this means generated column will be virtual.

• :unique: Whether to add a unique constraint or not. By default it omits the UNIQUE KEY keyword.

• :null: Allow or disallow null values. By default it omits keyword, meaning it falls back to database default.

• :primary_key: Whether column has a primary key or not. By default it omits the keyword PRIMARY KEY.

• :index: Whether to create an index after adding column or not.

After checking out the repo, install bundler with gem install bundler, and run bundle install to install dependencies. Then, run rake test to run the tests.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/munshkr/sequel-mysql_generated_columns.

MIT License

Copyright (c) 2016 Damián Silvani

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.