Operations

An Operation is like a Command, but with two key differences. First, an Operation retains a reference to the result object from the most recent time the operation was called, and delegates the methods defined by Cuprum::Result to the most recent result. This allows a called Operation to replace a Cuprum::Result in any code that expects or returns a result. Second, the #call method returns the operation instance, rather than the result itself.

These two features allow developers to simplify logic around calling and using the results of operations, and reduce the need for boilerplate code (particularly when using an operation as part of an existing framework, such as inside of an asynchronous worker or a Rails controller action).

class CreateBookOperation < Cuprum::Operation
  def process
    # Implementation here.
  end
end

# Defining a controller action using an operation.
class BooksController
  def create
    operation = CreateBookOperation.new

    operation.call(book_params)

    if operation.success?
      redirect_to(operation.value)
    else
      @book = operation.value

      render :new
    end
  end
end

Like a Command, an Operation can be defined directly by passing an implementation block to the constructor or by creating a subclass that overwrites the #process method.

An operation inherits the #call method from Cuprum::Command (see above), and delegates the #value, #error, #success?, and #failure methods to the most recent result. If the operation has not been called, these methods will return default values.

The Operation Mixin

The implementation of Cuprum::Operation is defined by the Cuprum::Operation::Mixin module, which provides the methods defined above. Any command class or instance can be converted to an operation by including (for a class) or extending (for an instance) the operation mixin.

---

Back to Documentation | Commands