module Enum::ValueConverter(T)
¶
Converter for value-based serialization and deserialization of enum type T.
The serialization format of Enum#to_json and Enum.from_json is based on
the member name. This converter offers an alternative based on the member value.
This converter can be used for its standalone serialization methods as a
replacement of the default strategy of Enum. It also works as a serialization
converter with JSON::Field and YAML::Field
require "json"
require "yaml"
enum MyEnum
ONE = 1
TWO = 2
end
class Foo
include JSON::Serializable
include YAML::Serializable
@[JSON::Field(converter: Enum::ValueConverter(MyEnum))]
@[YAML::Field(converter: Enum::ValueConverter(MyEnum))]
property foo : MyEnum = MyEnum::ONE
def initialize(@foo)
end
end
foo = Foo.new(MyEnum::ONE)
foo.to_json # => %({"foo":1})
foo.to_yaml # => %(---\nfoo: 1\n)
Note
Automatically assigned enum values are subject to change when the order of members by adding, removing or reordering them. This can affect the integrity of serialized data between two instances of a program based on different code versions. A way to avoid this is to explicitly assign fixed values to enum members.
Class methods¶
.from_json(pull : JSON::PullParser) : T
¶
(pull : JSON::PullParser) : T
Reads a serialized enum member by value from pull.
See .to_json for reference.
Raises JSON::ParseException if the deserialization fails.
.from_yaml(ctx : YAML::ParseContext, node : YAML::Nodes::Node) : T
¶
(ctx : YAML::ParseContext, node : YAML::Nodes::Node) : T
Reads a serialized enum member by value from ctx and node.
See .to_yaml for reference.
Raises YAML::ParseException if the deserialization fails.
.to_json(member : T, json : JSON::Builder)
¶
(member : T, json : JSON::Builder)
Serializes enum member member by value.
For both flags enums and non-flags enums, the value of the enum member is used for serialization.
enum Stages
INITIAL
SECOND_STAGE
end
Enum::ValueConverter.to_json(Stages::INITIAL) # => %(0)
Enum::ValueConverter.to_json(Stages::SECOND_STAGE) # => %(1)
@[Flags]
enum Sides
LEFT
RIGHT
end
Enum::ValueConverter.to_json(Sides::LEFT) # => %(1)
Enum::ValueConverter.to_json(Sides::LEFT | Sides::RIGHT) # => %(3)
Enum::ValueConverter.to_json(Sides::All) # => %(3)
Enum::ValueConverter.to_json(Sides::None) # => %(0)
Enum#to_json offers a different serialization strategy based on the member
name.
.to_yaml(member : T, yaml : YAML::Nodes::Builder)
¶
(member : T, yaml : YAML::Nodes::Builder)
Serializes enum member member by value.
For both flags enums and non-flags enums, the value of the enum member is used for serialization.
enum Stages
INITIAL
SECOND_STAGE
end
Enum::ValueConverter.to_yaml(Stages::INITIAL) # => %(--- 0\n)
Enum::ValueConverter.to_yaml(Stages::SECOND_STAGE) # => %(--- 1\n)
@[Flags]
enum Sides
LEFT
RIGHT
end
Enum::ValueConverter.to_yaml(Sides::LEFT) # => %(--- 1\n)
Enum::ValueConverter.to_yaml(Sides::LEFT | Sides::RIGHT) # => %(--- 3\n)
Enum::ValueConverter.to_yaml(Sides::All) # => %(--- 3\n)
Enum::ValueConverter.to_yaml(Sides::None) # => %(--- 0\n)
Enum#to_yaml offers a different serialization strategy based on the member
name.