# Activerecord::PGCollation

This gem adds support for creating and deleting collations. The collation feature allows specifying the sort order and character classification behavior of data per-column, or even per-operation. This alleviates the restriction that the LC_COLLATE and LC_CTYPE settings of a database cannot be changed after its creation.

## schema.rb Support

The motivation of this gem is to integrate postgres collations into your `schema.rb` file without switching to `structure.sql`.

```ruby
ActiveRecord::Schema.define(version: 2021_12_01_213707) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  # These are collations that must be created before they can be used in the schema definition
  create_collation "case_insensitive", lc_collate: "und-u-ks-level2", lc_ctype: "und-u-ks-level2", provider: "icu", deterministic: false
end
```

## Installation

Add this line to your application's Gemfile:

```ruby
gem 'activerecord-pg_collation'
```

And then execute:

    $ bundle install

Or install it yourself as:

    $ gem install activerecord-pg_collation

## Usage

### Create a collation

This gem adds the `create_collation` migration helper for creating collations:

```ruby
create_collation "collation_name", options
```

For more information about available options visit: https://www.postgresql.org/docs/current/sql-createcollation.html

For example, this migration creates a case insensitive collation:

```ruby
class CreateCaseInsensitiveCollation < ActiveRecord::Migration[6.1]
  def change
    create_collation "case_insensitive", provider: "icu", locale: "und-u-ks-level2", deterministic: false
  end
end
```

### Delete a collation

This gem adds the `drop_collation` migration helper for deleting collations:

```ruby
drop_collation "collation_name", option
```

By default `option` is equals to `"RESTRICT"`. For more information visit https://www.postgresql.org/docs/current/sql-dropcollation.html

For example, this migration deletes the case insensitive collation previously created:

```ruby
class DropCaseInsensitiveCollation < ActiveRecord::Migration[6.1]
  def change
    drop_collation "case_insensitive"
  end
end
```

### Use a collation with an index

```ruby
class AddIndexToSomeTable < ActiveRecord::Migration[6.1]
  def change
    add_index :some_table, "some_string_field COLLATE case_insensitive, another_string_field COLLATE case_insensitive", unique: true
  end
end
```

## Development

After checking out the repo, run `bin/setup` to install dependencies. Then, run `bundle exec rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.

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 the created tag, and push the `.gem` file to [rubygems.org](https://rubygems.org).

## License

The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).