Method: Jinx::Mergeable#merge_attribute

Defined in:
lib/jinx/resource/mergeable.rb

#merge_attribute(attribute, newval, matches = nil) {|value| ... } ⇒ Object

Merges the value newval into the attribute as follows:

  • If the value is nil, empty or equal to the current attribute value, then no merge is performed.

  • Otherwise, if a merger block is given to this method, then that block is called to perform the merge.

  • Otherwise, if the attribute is a non-domain attribute and the current value is non-nil, then no merge is performed.

  • Otherwise, if the attribute is a non-domain attribute and the current value is nil, then set the attribute to the newval.

  • Otherwise, if the attribute is a domain non-collection attribute, then newval is recursively merged into the current referenced domain object.

  • Otherwise, attribute is a domain collection attribute and matching newval members are merged into the corresponding current collection members and non-matching newval members are added to the current collection.

Parameters:

  • attribute (Symbol) —

    the merge attribute

  • newval —

    the value to merge

  • the ({Resource => Resource}, nil) —

    optional merge source => target reference matches

Yields:

  • (value) —

    the optional filter block

Yield Parameters:

  • value —

    the source merge attribute value

Returns:

  • the merged attribute value



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# File 'lib/jinx/resource/mergeable.rb', line 76

def merge_attribute(attribute, newval, matches=nil)
  # the previous value
  oldval = send(attribute)
  # Filter the newval into the srcval.
  srcval = if newval and block_given? then
    if newval.collection? then
      newval.select { |v| yield(v) }
    elsif yield(newval) then
      newval
    end
  else
    newval
  end
  
  # If there is no point in merging, then bail. 
  return oldval if srcval.nil_or_empty? or mergeable__equal?(oldval, newval)
  
  # Discriminate between a domain and non-domain attribute.
  prop = self.class.property(attribute)
  if prop.domain? then
    merge_domain_property_value(prop, oldval, srcval, matches)
  else
    merge_nondomain_property_value(prop, oldval, srcval)
  end
end