Protocol for encoding values to JSON for LiveReact.

This protocol is used to safely transform structs into plain maps before calculating JSON patches. It ensures that struct fields are explicitly exposed and prevents accidental exposure of sensitive data.

It's very similar to Jason.Encoder, but it's converting structs to maps instead of strings.

Deriving

The protocol allows leveraging Elixir's @derive feature to simplify protocol implementation in trivial cases. Accepted options are:

• :only - encodes only values of specified keys.
• :except - encodes all struct fields except specified keys.

By default all keys except the :__struct__ key are encoded.

Example

defmodule User do
  @derive LiveReact.Encoder
  defstruct [:name, :email, :password]
end

If we called @derive {LiveReact.Encoder, only: [:name, :email]}, only the specified fields would be encoded. If we called @derive {LiveReact.Encoder, except: [:password]}, all fields except the specified ones would be encoded.

Deriving outside of the module

Protocol.derive(LiveReact.Encoder, User, only: [...])

Custom implementations

defimpl LiveReact.Encoder, for: User do
  def encode(struct, opts) do
    struct
    |> Map.take([:first, :second])
    |> LiveReact.Encoder.encode(opts)
  end
end