Versionary

Add versioning to your Elixir Plug and Phoenix built API's.

Installation

The package can be installed by adding :versionary to your list of dependencies in mix.exs:

def deps do
  [
    {:versionary, "~> 0.3"}
  ]
end

Usage

def MyAPI.Router do
  use Plug.Router

  plug Versionary.Plug.VerifyHeader, versions: ["application/vnd.app.v1+json"]

  plug Versionary.Plug.EnsureVersion, handler: MyAPI.MyErrorHandler

  plug :match
  plug :dispatch
end

MIME Support

It's possible to verify versions against configured MIME types. If multiple MIME types are passed and at least one matches the version will be considered valid.

config :mime, :types, %{
  "application/vnd.app.v1+json" => [:v1],
  "application/vnd.app.v2+json" => [:v2]
}

plug Versionary.Plug.VerifyHeader, accepts: [:v1, :v2]

Please note that whenever you change media type configurations you must recompile the mime library.

To force mime to recompile run mix deps.clean --build mime.

Identifying Versions

When a version has been verified :version and :raw_version private keys will be added to the conn. These keys will contain version that has been verified.

The :version key may contain either the string version provided by the request or, if configured, the MIME extension. The :raw_version key will always contain the string version provided by the request.

Phoenix

Versionary is just a plug. That means Versionary works with Phoenix out of the box. However, if you'd like Versionary to render a Phoenix error view when verification fails use Versionary.Plug.PhoenixErrorHandler.

defmodule MyAPI.Router do
  use MyAPI.Web, :router

  pipeline :api do
    plug Versionary.Plug.VerifyHeader, accepts: [:v1, :v2]

    plug Versionary.Plug.EnsureVersion, handler: Versionary.Plug.PhoenixErrorHandler
  end

  scope "/", MyAPI do
    pipe_through :api

    get "/my_controllers", MyController, :index
  end
end

Handling Multiple Versions

You can pattern match which version of a controller action to run based on the :version (or :raw_version) private key provided by the conn.

defmodule MyAPI.MyController do
  use MyAPI, :controller

  def index(%{private: %{version: [:v1]}} = conn, _params) do
    render(conn, "index.v1.json", %{})
  end

  def index(%{private: %{version: [:v2]}} = conn, _params) do
    render(conn, "index.v2.json", %{})
  end
end

Plug API

Versionary.Plug.VerifyHeader

Verify that the version passed in to the request as a header is valid. If the version is not valid then the request will be flagged.

This plug will not handle an invalid version. If you would like to halt the request and handle an invalid version please see Versionary.Plug.EnsureVersion.

Options

accepts - a list of strings or atoms representing versions registered as MIME types. If at least one of the registered versions is valid then the request is considered valid.

versions - a list of strings representing valid versions. If at least one of the provided versions is valid then the request is considered valid.

header - the header used to provide the requested version (Default: Accept)

Versionary.Plug.EnsureVersion

Checks to see if the request has been flagged with a valid version. If the version is valid, the request continues, otherwise the request will halt and the handler will be called to process the request.

Options

handler - the module used to handle a request with an invalid version (Default: Versionary.Plug.ErrorHandler)

Versionary.Plug.Handler

Behaviour for handling requests with invalid versions. You can create your own custom handler with this behaviour.

Copyright and License

This library is licensed under the MIT license.

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