# `Mar`

Using `Mar` makes the module a route.
It injects `Mar.Route` protocol and a struct.
Set a `path` or the default is "/".
Add parameters in the path or in the `params` list.

```elixir
defmodule MyApp do
  use Mar, path: "/post/:id", params: [:likes, :comment]
end
```

Name your function after the HTTP method.
Take HTTP parameters from a map.
Return a response body with text.

```elixir
def get(%{id: id}) do
  "You are reading #{id}"
end
```

Returning a map will send a response in JSON.

```elixir
def post(%{id: id, comment: comment}) do
  %{
    id: id,
    comment: comment
  }
end
```

Return a tuple to set HTTP status and headers.

```elixir
def delete(%{id: _id}) do
  # {status, header, body}
  {301, [location: "/"], nil}
end
```

`Mar.Route` protocol lets you access `Plug.Conn`.

```elixir
defimpl Mar.Route do
  # Mar.Route.MyApp

  def before_action(route) do
    # Access `route.conn` before the actions you have defined.
    route
  end

  def after_action(route) do
    # Access `route.conn` after the actions you have defined.
    route
  end
end
```

---

*Consult [api-reference.md](api-reference.md) for complete listing*