Class: RubyNestNats::Controller

Inherits:
Object
  • Object
show all
Defined in:
lib/ruby_nest_nats/controller.rb

Overview

Create controller classes which inherit from RubyNestNats::Controller in order to give your message listeners some structure.

Constant Summary collapse

NO_QUEUE_GIVEN =

:nodoc:

:ruby_nest_nats_super_special_no_op_queue_symbol_qwertyuiop1234567890

Class Method Summary collapse

Class Method Details

.default_queue(some_queue = NO_QUEUE_GIVEN) ⇒ Object

Default queue for the controller. Falls back to the client’s default queue if the controller’s default queue is nil.

  • Call with no argument (::default_queue) to get the default queue.

  • Call as a macro with an argument (+default_queue “something”+) to set the default queue.

If omitted, the controller will fall back on the global default queue assigned with RubyNestNats::Client::default_queue=. If no default queue is set in either the controller or globally, then the default queue will be blank. Set the default queue to nil in a controller to override the global default queue and explicitly make the default queue blank for that controller.

Examples:

class FoobarNatsController < RubyNatsController
  default_queue "foobar"

  # ...
end


34
35
36
37
38
39
40
41
42
43
 
# File 'lib/ruby_nest_nats/controller.rb', line 34

def default_queue(some_queue = NO_QUEUE_GIVEN)
  # +NO_QUEUE_GIVEN+ is a special symbol (rather than +nil+) so that the
  # default queue can be "unset" to +nil+ (given a non-+nil+ global
  # default set with +RubyNestNats::Client::default_queue=+).
  if some_queue == NO_QUEUE_GIVEN
    @default_queue || Client.default_queue
  else
    @default_queue = Utils.presence(some_queue.to_s)
  end
end

.response(queue: nil, &block) ⇒ Object

You can register a response for the built-up subject/pattern string using the ::response macro. Pass a block to ::response which optionally takes two arguments (the same arguments supplied to the block of RubyNestNats::Client::reply_to). The result of that block will be sent as a response to the message received.

Examples:

class FoobarNatsController < RubyNatsController
  # ...

  subject "hello" do
    subject "wassup" do
      response do |data, subject|
        # The subject at this point is "hello.wassup".
        # Assume the message sent a JSON payload of {"name":"Bob"}
        # in this example.
        # We'll reply with a string response:
        "I'm all right, #{data['name']}"
      end
    end

    subject "howdy" do
      response do |data, subject|
        # The subject at this point is "hello.howdy".
        # Assume the message sent a JSON payload of {"name":"Bob"}
        # in this example.
        # We'll reply with a JSON response (a Ruby +Hash+):
        { message: "I'm okay, #{data['name']}. Thanks for asking!" }
      end
    end
  end
end


134
135
136
137
 
# File 'lib/ruby_nest_nats/controller.rb', line 134

def response(queue: nil, &block)
  response_queue = Utils.presence(queue.to_s) || current_queue || default_queue
  Client.reply_to(current_subject, queue: response_queue, &block)
end

.subject(subject_segment, queue: nil) ⇒ Object

Use the ::subject macro to create a block for listening to that subject segment. Nested calls to ::subject will append each subsequent subject/pattern string to the last (joined by a periods). There is no limit to the level of nesting.

NOTE: The following two examples do exactly the same thing.

Examples:

class FoobarNatsController < RubyNatsController
  # ...

  subject "hello.wassup" do
    response do |data, subject|
      # The subject at this point is "hello.wassup"
      # ...
    end
  end

  subject "hello.howdy" do
    response do |data, subject|
      # The subject at this point is "hello.howdy"
      # ...
    end
  end
end
class FoobarNatsController < RubyNatsController
  # ...

  subject "hello" do
    subject "wassup" do
      response do |data, subject|
        # The subject at this point is "hello.wassup"
        # ...
      end
    end

    subject "howdy" do
      response do |data, subject|
        # The subject at this point is "hello.howdy"
        # ...
      end
    end
  end
end


92
93
94
95
96
97
98
99
 
# File 'lib/ruby_nest_nats/controller.rb', line 92

def subject(subject_segment, queue: nil)
  subject_chain.push(subject_segment)
  old_queue = current_queue
  self.current_queue = queue if Utils.present?(queue)
  yield
  self.current_queue = old_queue
  subject_chain.pop
end