Strukt

View Source JSON Support

Support for JSON serialization is built upon Ecto.embedded_dump/2, but must be explicitly enabled. This is to allow you to provide your own implementation if you don't desire to use the generated one. However, deriving the encoder is dead simple, and looks just like it would for any old struct. For example:

# defstruct/1
defmodule Person do
  @derives [Jason.Encoder]
  defstruct do
    field :name, :string

    timestamps()
  end
end

# defstruct/2
defstruct Person do
  @derives [Jason.Encoder]

  field :name, :string

  timestamps()
end

Internally, defstruct provides a concrete implementation of Jason.Encoder that calls out to Ecto.embedded_dump/2. For deserialization, from_json/1 is defined for the struct's module, and uses Ecto.embedded_load/3 to deserialize back to the original struct using the canonical deserializer for each field type.

The difference versus just letting @derives [Jason.Encoder] do its thing, is that embedded_dump/2 and embedded_load/3 ensure that the types are dumped/loaded according to their respective Ecto type definitions, which should produce canonical JSON encodings, as opposed to naively encoding fields based on their raw Elixir representation.

NOTE: Currently, we only implement special support for Jason.Encoder, if you use another JSON library, it is recommended that you implement the relevant encoder yourself using Ecto.embedded_dump/2, much like we do for our implementation of Jason.Encoder.