DeclaredPropertyManager.rst

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.

ruby

def attributes_nil_hash

@_attributes_nil_hash |attr_hash|

registered_properties.each_pair do

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.

ruby

def attributes_string_map

@_attributes_string_map |attr_hash|

attributes_nil_hash.each_key { attr_hash[k.to_sym] = k }

end.freeze

end

#convert_properties_to

ruby

def convert_properties_to(obj, medium, properties)

converter = medium == :ruby ? :to_ruby : :to_db properties.each_pair do next if skip_conversion?(obj, attr, value) properties[attr] = converted_property(primitive_type(attr.to_sym), value, converter) end

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.

ruby

def declared_property_defaults

@_default_property_values ||= {}

end

#initialize

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

ruby

def initialize(klass)

@klass = klass

end

#klass

Returns the value of attribute klass

ruby

def klass

@klass

end

#magic_typecast_properties

ruby

def magic_typecast_properties

@magic_typecast_properties ||= {}

end

#magic_typecast_properties_keys

ruby

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.

ruby

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

ruby

def registered_properties

@_registered_properties ||= {}

end

#serialize

ruby

def serialize(name, coder = JSON)

@serialize ||= {} @serialize[name] = coder

end

#serialized_properties

ruby

def serialized_properties

@serialize ||= {}

end

#serialized_properties=

ruby

def serialized_properties=(serialize_hash)

@serialized_property_keys = nil @serialize = serialize_hash.clone

end

#serialized_properties_keys

ruby

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.

ruby

def string_key(k)

attributes_string_map[k] || string_map_id_property(k) || k.to_s

end

#unregister

ruby

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.

ruby

def upstream_primitives

@upstream_primitives ||= {}

end