JSON::Serializable::Fake

JSON::Serializable::Fake allows method calls to generate JSON content.

Example

require "json/fakefield"

class Sum
  include JSON::Serializable
  include JSON::Serializable::Fake

  property a : UInt32
  property b : UInt32

  def initialize(@a, @b)
  end

  @[JSON::FakeField]
  def sum(json : ::JSON::Builder) : Nil
    json.number(a + b)
  end
end

s = Sum.new(10, 5)
puts s.to_json # => { "a": 10, "b": 5, "sum": 15 }

Usage

JSON::Serializable::Fake will create extend_to_json (which will actually call your methods) and will replace the on_to_json method generated by JSON::Serializable.

JSON::Serializable::Fake is compatible with JSON::Serializable::Unmapped and JSON::Serializable::Strict as long as JSON::Serializable::Fake is included last.

You can customize the behavior of each fake field via the JSON::FakeField annotation. Method calls MUST accept ::JSON::Builder as a parameter and return ::Nil. The construction of JSON elements is handled via ::JSON::Builder.

JSON::FakeField properties:

• key: an explicit name of the field added to the json string (by default it uses the method name)
• suppress_key: if true no json field will be implictly added. This allows the method call to create multiple json fields

WARNING: At the moment it is not possible to deserialize fake fields into a method call. There is no technical limitation, just a lack of time. However, you can use JSON::Serializable::Unmapped to capture all the fake fields.