Class: Humidifier::Reservoir::BaseMapper

Inherits:
Object
  • Object
show all
Defined in:
lib/humidifier/reservoir/base_mapper.rb

Overview

The parent class for mapper classes. These classes are used to transform arbitrary attributes coming from the user-provided YAML files into valid CloudFormation attributes that can then be used in the template. This class provides an easy-to-extend DSL that allows for default attributes specifying custom attributes.

Constant Summary

COMMON_ATTRIBUTES =

The list of attributes that are common to all resources that need to be handles separately.

Resource::COMMON_ATTRIBUTES.values

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.attribute(name, &block) ⇒ Object

Defines a custom attribute. The given block will receive the user-provided value for the attribute. The block should return a hash where the keys are valid humidifier properties and the values are valid values for those properties. In the below example, we specify the group attribute which maps to the groups attribute after some transformation.

attribute :group do |group|
  groups = GROUPS[group]
  groups.any? ? { groups: GROUPS[group] } : {}
end



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# File 'lib/humidifier/reservoir/base_mapper.rb', line 25

def attribute(name, &block)
  define_method(:attribute_#{name}", &block)
  attribute_methods << name
end

.attribute_methods ⇒ Object

The names of the custom attribute methods.



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# File 'lib/humidifier/reservoir/base_mapper.rb', line 31

def attribute_methods
  @attribute_methods ||= []
end

.defaults(&block) ⇒ Object

Defines the default attributes that should be applied to all resources of this type. The given block will be passed the logical resource name that the user specified for the resource. The block should return a hash where the keys are valid humidifier properties and the values are valid values for those properties. In the example below, the user_name property is set based on the logical name.

defaults do |name|
  { user_name: name }
end



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# File 'lib/humidifier/reservoir/base_mapper.rb', line 45

def defaults(&block)
  define_method(:attribute_defaults, &block)
end

Instance Method Details

#resource_for(clazz, name, attributes) ⇒ Object

Builds a humidifier resource using the given humidifier resource class, the logical name for the resource, and the user-specified attributes.



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# File 'lib/humidifier/reservoir/base_mapper.rb', line 52

def resource_for(clazz, name, attributes)
  mapped = respond_to?(:attribute_defaults) ? attribute_defaults(name) : {}

  attributes.each do |key, value|
    mapped.merge!(mapped_from(clazz, key, value))
  end

  common_attributes = common_attributes_from(mapped)

  resource = clazz.new(mapped)
  resource.update_attributes(common_attributes)
  resource
end