DeclaredPropertyManager

The DeclaredPropertyuManager holds details about objects created as a result of calling the #property class method on a class that includes Neo4j::ActiveNode or Neo4j::ActiveRel. There are many options that are referenced frequently, particularly during load and save, so this provides easy access and a way of separating behavior from the general Active{obj} modules.

See Neo4j::Shared::DeclaredProperty for definitions of the property objects themselves.

Constants

Files

• lib/neo4j/shared/declared_property_manager.rb:8

Methods

#attributes_nil_hash

During object wrap, a hash is needed that contains each declared property with a nil value. The active_attr dependency is capable of providing this but it is expensive and calculated on the fly each time it is called. Rather than rely on that, we build this progressively as properties are registered. When the node or rel is loaded, this is used as a template.

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def attributes_nil_hash
  @_attributes_nil_hash ||= {}.tap do |attr_hash|
    registered_properties.each_pair do |k, prop_obj|
      val = prop_obj.default_value
      attr_hash[k.to_s] = val
    end
  end.freeze
end

#attributes_string_map

During object wrapping, a props hash is built with string keys but Neo4j-core provides symbols. Rather than a to_s or symbolize_keys during every load, we build a map of symbol-to-string to speed up the process. This increases memory used by the gem but reduces object allocation and GC, so it is faster in practice.

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def attributes_string_map
  @_attributes_string_map ||= {}.tap do |attr_hash|
    attributes_nil_hash.each_key { |k| attr_hash[k.to_sym] = k }
  end.freeze
end

#convert_properties_to

Modifies a hash’s values to be of types acceptable to Neo4j or matching what the user defined using type in property definitions.

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def convert_properties_to(obj, medium, properties)
  direction = medium == :ruby ? :to_ruby : :to_db
  properties.each_pair do |key, value|
    next if skip_conversion?(obj, key, value)
    properties[key] = convert_property(key, value, direction)
  end
end

#convert_property

Converts a single property from its current format to its db- or Ruby-expected output type.

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def convert_property(key, value, direction)
  converted_property(primitive_type(key.to_sym), value, direction)
end

#declared_property_defaults

The :default option in Neo4j::ActiveNode#property class method allows for setting a default value instead of nil on declared properties. This holds those values.

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def declared_property_defaults
  @_default_property_values ||= {}
end

#initialize

Each class that includes Neo4j::ActiveNode or Neo4j::ActiveRel gets one instance of this class.

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def initialize(klass)
  @klass = klass
end

#klass

Returns the value of attribute klass

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def klass
  @klass
end

#magic_typecast_properties

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def magic_typecast_properties
  @magic_typecast_properties ||= {}
end

#magic_typecast_properties_keys

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def magic_typecast_properties_keys
  @magic_typecast_properties_keys ||= magic_typecast_properties.keys
end

#register

#property on an ActiveNode or ActiveRel class. The DeclaredProperty has specifics about the property, but registration makes the management object aware of it. This is necessary for type conversion, defaults, and inclusion in the nil and string hashes.

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def register(property)
  @_attributes_nil_hash = nil
  @_attributes_string_map = nil
  registered_properties[property.name] = property
  register_magic_typecaster(property) if property.magic_typecaster
  declared_property_defaults[property.name] = property.default_value if property.default_value
end

#registered_properties

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def registered_properties
  @_registered_properties ||= {}
end

#serialize

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def serialize(name, coder = JSON)
  @serialize ||= {}
  @serialize[name] = coder
end

#serialized_properties

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def serialized_properties
  @serialize ||= {}
end

#serialized_properties=

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def serialized_properties=(serialize_hash)
  @serialized_property_keys = nil
  @serialize = serialize_hash.clone
end

#serialized_properties_keys

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def serialized_properties_keys
  @serialized_property_keys ||= serialized_properties.keys
end

#string_key

but when this happens many times while loading many objects, it results in a surprisingly significant slowdown. The branching logic handles what happens if a property can’t be found. The first option attempts to find it in the existing hash. The second option checks whether the key is the class’s id property and, if it is, the string hash is rebuilt with it to prevent future lookups. The third calls to_s. This would happen if undeclared properties are found on the object. We could add them to the string map but that would result in unchecked, un-GCed memory consumption. In the event that someone is adding properties dynamically, maybe through user input, this would be bad.

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def string_key(k)
  attributes_string_map[k] || string_map_id_property(k) || k.to_s
end

#unregister

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def unregister(name)
  # might need to be include?(name.to_s)
  fail ArgumentError, "Argument `#{name}` not an attribute" if not registered_properties[name]
  declared_prop = registered_properties[name]
  registered_properties.delete(declared_prop)
  unregister_magic_typecaster(name)
  unregister_property_default(name)
end

#upstream_primitives

The known mappings of declared properties and their primitive types.

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def upstream_primitives
  @upstream_primitives ||= {}
end

#value_for_db

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def value_for_db(key, value)
  return value unless registered_properties[key]
  convert_property(key, value, :to_db)
end

#value_for_ruby

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def value_for_ruby(key, value)
  return unless registered_properties[key]
  convert_property(key, value, :to_ruby)
end