Module: Karafka::Helpers::ConfigRetriever

Included in:
Routing::ConsumerGroup, Routing::Topic
Defined in:
lib/karafka/helpers/config_retriever.rb

Overview

Note:

Worth noticing, that the value might be equal to false, so even then we need to return it. That’s why we check for nil?

A helper method that allows us to build methods that try to get a given attribute from its instance value and if it fails, will fallback to the default config or config.kafka value for a given attribute. It is used to simplify the checks. class Test

extend Karafka::Helpers::ConfigRetriever
config_retriever_for :start_from_beginning

end

Test.new.start_from_beginning #=> false test_instance = Test.new test_instance.start_from_beginning = true test_instance.start_from_beginning #=> true

Examples:

Define config retried attribute for start_from_beginning

Instance Method Summary collapse

Instance Method Details

#config_retriever_for(attribute) ⇒ Object

Builds proper methods for setting and retrieving (with fallback) given attribute value

Parameters:

  • attribute (Symbol) —

    attribute name based on which we will build accessor with fallback



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# File 'lib/karafka/helpers/config_retriever.rb', line 25

def config_retriever_for(attribute)
  attr_writer attribute unless method_defined? :"#{attribute}="

  # Don't redefine if we already have accessor for a given element
  return if method_defined? attribute

  define_method attribute do
    current_value = instance_variable_get(:"@#{attribute}")
    return current_value unless current_value.nil?

    value = if Karafka::App.config.respond_to?(attribute)
              Karafka::App.config.send(attribute)
            else
              Karafka::App.config.kafka.send(attribute)
            end

    instance_variable_set(:"@#{attribute}", value)
  end
end