class Humidifier::Reservoir::BaseMapper

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.

Constants

COMMON_ATTRIBUTES

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

Public Class Methods

attribute(name, &block) click to toggle source

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
# File lib/humidifier/reservoir/base_mapper.rb, line 25
def attribute(name, &block)
  define_method(:"attribute_#{name}", &block)
  attribute_methods << name
end
attribute_methods() click to toggle source

The names of the custom attribute methods.

# File lib/humidifier/reservoir/base_mapper.rb, line 31
def attribute_methods
  @attribute_methods ||= []
end
defaults(&block) click to toggle source

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
# File lib/humidifier/reservoir/base_mapper.rb, line 45
def defaults(&block)
  define_method(:attribute_defaults, &block)
end

Public Instance Methods

resource_for(clazz, name, attributes) click to toggle source

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

# 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

Private Instance Methods

common_attributes_from(mapped) click to toggle source
# File lib/humidifier/reservoir/base_mapper.rb, line 69
def common_attributes_from(mapped)
  COMMON_ATTRIBUTES.each_with_object({}) do |common_attribute, extract|
    extracted = mapped.delete(common_attribute)
    extract[common_attribute] = extracted if extracted
  end
end
mapped_from(clazz, key, value) click to toggle source
# File lib/humidifier/reservoir/base_mapper.rb, line 76
def mapped_from(clazz, key, value) # rubocop:disable Metrics/MethodLength
  if self.class.attribute_methods.include?(key.to_sym)
    public_send(:"attribute_#{key}", value)
  elsif clazz.prop?(key)
    { key.to_sym => value }
  elsif clazz.prop?("#{key}_id")
    { :"#{key}_id" => Humidifier.ref(value) }
  elsif COMMON_ATTRIBUTES.include?(key.to_sym)
    { key.to_sym => value }
  else
    raise Error, "Invalid attribute: #{key}"
  end
end