charleseff/tphases

# TPhases

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TPhases (Transactional Phases) is a support framework that helps you isolate database transactional code in your Ruby app by providing read-only, write-only, and no-transaction-allowed phases.

The way it accomplishes this is with the methods `TPhases.read_phase`, `TPhases.write_phase` and `TPhases.no_transactions_phase` which take blocks.  Here is a simple example inside of a controller action:

```ruby
class BarsController < ApplicationController

  def update
    TPhases.read_phase do
      @bar = Bar.find(params[:id])
    end
    
    TPhases.write_phase do
      @bar.update_attributes(params[:bar])
    end

    TPhases.no_transactions_phase do
      process(@bar)
      redirect_to @bar
    end
  end
end
```

** Currently supports ActiveRecord only.  Planned support includes Memcached, Redis, MongoDB, and more.

## Installation

Add this line to your application's Gemfile:

    gem 'tphases'

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install tphases

Somewhere in the initialization process of your app, call 

    TPhases.initiate!

## Usage

### Environments

#### In production:
The `read_phase`, `write_phase`, and `no_transaction_phase` methods simply yield to the block given.

#### In development:

##### `read_phase`
throws an exception if a database transaction is attempted within its block which is a write.  This is known as a "read transactional violation".

##### `write_phase`
throws an exception if a database transaction is attempted within its block which is a read.  This is a write transactional violation.

##### `no_transactions_phase`
throws an exception if any database transaction is attempted within its block.

#### In test:
If a transactional violation occurs in a TPhase, the code will continue to run, but the test will fail at the end citing the list of transactional violations that occurred.

### Methods

#### `ensure_no_transactions_on`
Call `ensure_no_transactions_on` on controllers to prevent DB transactions within the view and action of a controller action.  e.g.:

```ruby
class BarsController < ApplicationController

  ensure_no_transactions_on [:show,:update]
end
```

#### `ignore_phases`
Call `ignore_phases` to disable TPhases within the block passed



## Contributing

1. Fork it
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Added some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create new Pull Request