Protocol for encoding values to JSON for LiveVue.

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

Let's assume a presence of the following struct:

defmodule User do
  defstruct [:name, :email, :password]
end

If we were to call @derive LiveVue.Encoder just before defstruct, an implementation would be generated that encodes all fields except :__struct__:

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

If we called @derive {LiveVue.Encoder, only: [:name, :email]}, only the specified fields would be encoded:

defmodule User do
  @derive {LiveVue.Encoder, only: [:name, :email]}
  defstruct [:name, :email, :password]
end

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

defmodule User do
  @derive {LiveVue.Encoder, except: [:password]}
  defstruct [:name, :email, :password]
end

Deriving outside of the module

If you don't own the struct you want to encode, you may use Protocol.derive/3 placed outside of any module:

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

Custom implementations

You may define your own implementation for the struct:

defimpl LiveVue.Encoder, for: User do def encode(struct, opts) do

struct
|> Map.take([:first, :second])
|> LiveVue.Encoder.encode(opts)

end end