Token protocol to be used with the Pluggable and Pluggable.Builder modules.

When implementing pipelines using this library, a token holds the state and is passed on from step to step within the pipeline.

deriving-pluggable-token

Deriving Pluggable.Token

The simplest way to use this library is to define a token module which derives Pluggable.Token and defines a struct which, among others defines the keys:

• :halted - the boolean status on whether the pipeline was halted
• :assigns - shared user data as a map

Example:

defmodule MyPipeline.Token do
  @derive Pluggable.Token
  defstruct [
    halted: false,
    assigns: %{},
    # other state
  ]
end

If the fields holding these two states are named differently, pass the fields as options to @derive:

defmodule MyPipeline.Token do
  @derive {Pluggable.Token, halted_key: :stopped, assigns_key: :shared_state}
  defstruct [
    stopped: false,
    shared_state: %{},
    # other state
  ]
end

implementing-pluggable-token

Implementing Pluggable.Token

Pluggable.Token can be implemented. The following is the default implementation when deriving Pluggable.Token

defmodule MyPipeline.Token do
  defstruct [
    halted: nil,
    assigns: %{},
    # other state
  ]
end

defimpl Pluggable.Token, for: MyPipeline.Token do
  def halted?(token), do: token.halted

  def halt(token), do: %{token | halted: true}

  def assign(%MyPipeline.Token{assigns: assigns} = token, key, value) when is_atom(key) do
    %{token | assigns: Map.put(assigns, key, value)}
  end
end