EctoCommand.Middleware behaviour (EctoCommand v0.2.7)

Middleware provides an extension point to add functions that you want to be called for every command execution

Implement the EctoCommand.Middleware behaviour in your module and define the before_execution/2, after_execution/2, after_failure/2 and invalid/2 callback functions.

Example middleware

defmodule SampleMiddleware do
  @behaviour EctoCommand.Middleware

  @impl true
  def before_execution(pipeline, _opts) do
    pipeline
    |> Pipeline.assign(:some_data, :some_value)
    |> Pipeline.update!(:command, fn command -> %{command | name: "updated-name"} end)
  end

  @impl true
  def after_execution(pipeline, _opts) do
    Logger.debug("Command executed successfully", command: pipeline.command, result: Pipeline.response(pipeline))

    pipeline
  end

  @impl true
  def after_failure(pipeline, _opts) do
    Logger.error("Command execution fails", command: pipeline.command, error: Pipeline.response(pipeline))

    pipeline
  end

  @impl true
  def invalid(pipeline, _opts) do
    Logger.error("invalid params received", params: pipeline.params, error: Pipeline.response(pipeline))

    pipeline
  end
end

Summary

Types

pipeline()

Callbacks

after_execution(pipeline, opts)

Is executed following a sucessful command execution. In this function, if you'd like, you could alter the returned value.

after_failure(pipeline, opts)

Is executed after a failed command execution. In this function you could, if you wish, also update the returned value.

before_execution(pipeline, opts)

Is executed before command execution, and only if the command is valid. In this function, if you'd like, you might update the command that will be executed.

invalid(pipeline, opts)

Is executed when the command's inputs are invalid.

Types

pipeline()

@type pipeline() :: %EctoCommand.Middleware.Pipeline{
  assigns: term(),
  command: term(),
  error: term(),
  halted: term(),
  handler: term(),
  metadata: term(),
  middlewares: term(),
  params: term(),
  response: term()
}

Callbacks

after_execution(pipeline, opts)

@callback after_execution(pipeline :: pipeline(), opts :: Keyword.t()) :: pipeline()

Is executed following a sucessful command execution. In this function, if you'd like, you could alter the returned value.

Example

@impl true
def after_execution(pipeline, _opts) do
  Logger.debug("Command executed successfully", command: pipeline.command, result: Pipeline.response(pipeline))

  pipeline
end

after_failure(pipeline, opts)

@callback after_failure(pipeline :: pipeline(), opts :: Keyword.t()) :: pipeline()

Is executed after a failed command execution. In this function you could, if you wish, also update the returned value.

Example

@impl true
def after_failure(pipeline, _opts) do
  Logger.error("Command execution fails", command: pipeline.command, error: Pipeline.response(pipeline))

  pipeline
end

before_execution(pipeline, opts)

@callback before_execution(pipeline :: pipeline(), opts :: Keyword.t()) :: pipeline()

Is executed before command execution, and only if the command is valid. In this function, if you'd like, you might update the command that will be executed.

Example

@impl true
def before_execution(pipeline, _opts) do
  pipeline
  |> Pipeline.assign(:some_data, :some_value)
  |> Pipeline.update!(:command, fn command -> %{command | name: "updated-name"} end)
end

invalid(pipeline, opts)

@callback invalid(pipeline :: pipeline(), opts :: Keyword.t()) :: pipeline()

Is executed when the command's inputs are invalid.

Example

@impl true
def invalid(pipeline, _opts) do
  Logger.error("invalid params received", params: pipeline.params, error: Pipeline.response(pipeline))

  pipeline
end