Class: ValueFetcher

Inherits:
Object
  • Object
show all
Defined in:
lib/serializer/value_fetcher.rb

Defined Under Namespace

Classes: SerializerError

Constant Summary collapse

ARRAYS = 
%w[
  Array
  ActiveRecord_AssociationRelation
  ActiveRecord_Associations_CollectionProxy
].freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attribute, object, serializer) ⇒ ValueFetcher

Returns a new instance of ValueFetcher.



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# File 'lib/serializer/value_fetcher.rb', line 16

def initialize(attribute, object, serializer)
  @attribute = attribute
  @values = [
    StaticValue.new(attribute),
    SerializedValue.new(attribute, serializer),
    HashValue.new(attribute, object),
    ObjectValue.new(attribute, object)
  ]
end

Class Method Details

.fetch(attribute, object, serializer) ⇒ Object 



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# File 'lib/serializer/value_fetcher.rb', line 10

def self.fetch(attribute, object, serializer)
  new(attribute, object, serializer).fetch
end

Instance Method Details

#array? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/serializer/value_fetcher.rb', line 56

def array?
  ARRAYS.any? { |match| value.class.to_s.end_with?(match) }
end

#fetch ⇒ Object 



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# File 'lib/serializer/value_fetcher.rb', line 26

def fetch
  serializer = @attribute.serializer

  return value unless serializer

  if array?
    value.map { |item| serializer.new(item).to_h }
  else
    serializer.new(value).to_h
  end
end

#value ⇒ Object

Fetches a value from an attribute by checking if there’s a .. .. static value set, or a .. .. method defined in the serializer, or a .. .. method/attribute defined in the object or .. .. it raises an error



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# File 'lib/serializer/value_fetcher.rb', line 43

def value
  @value ||= begin
    extracted_value = @values.detect(&:precondition?)

    if extracted_value.nil?
      raise SerializerError,
            "unknown attribute '#{@values[0].extraction_key}'"
    end

    extracted_value.value
  end
end