[](https://travis-ci.org/bolshakov/active_record-sequence)
# ActiveRecord::Sequence
Access to [PostgreSQL's Sequences](https://www.postgresql.org/docs/8.1/static/sql-createsequence.html)
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'active_record-sequence'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install active_record-sequence
## Usage
By default new sequence starts from `1`:
```ruby
sequence = ActiveRecord::Sequence.create('numbers')
```
`#next` returns next value in the sequence:
```ruby
sequence.next #=> 1
sequence.next #=> 2
```
`#peek` returns current value:
```ruby
sequence.peek #=> 2
```
You can start a sequence with specific value:
```ruby
sequence = ActiveRecord::Sequence.create('numbers', start: 42)
sequence.next #=> 42
sequence.next #=> 43
```
Specify custom increment value:
```ruby
sequence = ActiveRecord::Sequence.create('numbers', increment: 3)
sequence.next #=> 1
sequence.next #=> 4
```
If you pass negative increment, a sequence will be decreasing:
```ruby
sequence = ActiveRecord::Sequence.create('numbers', increment: -3)
sequence.next #=> -1
sequence.next #=> -4
```
To limit number of elements in a sequence specify `max` value:
```ruby
sequence = ActiveRecord::Sequence.create('numbers', max: 2)
sequence.next #=> 1
sequence.next #=> 2
sequence.next #=> fail with StopIteration
```
Decreasing sequence may be limited as well:
```ruby
sequence = ActiveRecord::Sequence.create('numbers', min: -2, increment: -1)
sequence.next #=> -1
sequence.next #=> -2
sequence.next #=> fail with StopIteration
```
To define infinite sequence, use `cycle` option:
```ruby
sequence = ActiveRecord::Sequence.create('numbers', max: 2, cycle: true)
sequence.next #=> 1
sequence.next #=> 2
sequence.next #=> 1
sequence.next #=> 2
# etc.
```
You con use previously created sequence by instantiating `Sequence` class:
```ruby
ActiveRecord::Sequence.create('numbers', max: 2, cycle: true)
sequence = ActiveRecord::Sequence.new('numbers')
sequence.next #=> 1
sequence.next #=> 2
sequence.next #=> 1
```
To destroy a sequence:
```ruby
ActiveRecord::Sequence.drop('numbers')
```
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake` 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 tags, and push the `.gem`
file to [rubygems.org](https://rubygems.org).
We test this gem against different versions of `ActiveRecord` using [appraisal](https://github.com/thoughtbot/appraisal) gem.
To regenerate gemfiles run:
$ appraisal install
To run specs against all versions:
$ appraisal rake spec
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/bolshakov/active_record-sequence.