Trot is an Elixir web micro-framework based on Plug and Cowboy. The goal of Trot is to make common patterns in Plug easier to use, particularly when writing APIs, without sacrificing flexibility.
Add Trot as a dependency to your mix.exs file:
defp deps do
[{:trot, github: "hexedpackets/trot"}]
endThe following configuration options are supported by the server:
config :trot, :port, 4000: port to listen on for incoming HTTP requests. Defaults to "4000".
config :trot, :router, MyApp.Router: module to route requests to. Defaults to "Trot.NotFound".
config :trot, :heartbeat, "/heartbeat": path to setup a heartbeat route. This will always return 200 with a body of
"OK". Defaults to "/heartbeat". NOTE: This value will only have an effect when PlugHeartbeat is part of the plug list.
config :trot, :pre_routing, ["Elixir.CustomPlug": [plug_arg: value]]: Plugs that should be run before routing a request along with their arguments. Defaults to setting up "Trot.LiveReload", "Plug.Logger", "Plug.Parsers", and "PlugHeartbeat" in that order.
config :trot, :post_routing, ["Elixir.CustomPlug": [plug_arg: value]]: Plugs that should be run after routing a request along with their arguments. Defaults to "[]".
Finally, put use Trot.Router to the top of your module. This will add route macros and setup the plug pipeline at compile time.
To get a basic devserver up and running, make sure you add a Router module in the config as described above, and then simply
$ mix trot.server
Note: You can also start the server as well as an iex shell by running iex -S mix
Routes are specified using one of the HTTP method macros: get/3, post/3, put/3, patch/3, delete/3, options/3. The first argument is a the path to route to, the second (optional) argument is a keyword list of any options to match against, and the last argument is the block of code to execute. Examples are below.
If @path_root is specified, it will be prefixed to all routes in that module.
Routes can be setup in different modules and imported into the main router with the import_routes/1 macro, which takes a module name as the only argument. Note that ordering matters as normal Elixir pattern matching rules apply to imported routes.
A default 404 response can be enabled by putting import_routes Trot.NotFound or use Trot.NotFound at the end of the module.
All of the following are valid return values from handlers and will be parsed into full HTTP responses:
- String of response body
- Status code, either numeric or an atom from
Plug.Conn.Status {code, body}{code, body, headers}- JSONable object
{code, object}{code, object, headers}{:redirect, location}{:badrpc, error}%Plug.Conn{}
defmodule SoLoMoApp.Router do
use Trot.Router
# Setup a static route to priv/static/assets
static "/css", "assets"
# Returns an empty body with a status code of 400
get "/bad" do
:bad_request
end
# Sets the status code to 200 with a text body
get "/text" do
"Thank you for your question."
end
# Redirect the incoming request
get "/text/body", headers: ["x-text-type": "question"] do
{:redirect, "/text"}
end
# Sets the status code to 201 with a text body
get "/text/body" do
{201, "optimal tip-to-tip efficiency"}
end
# Sets status code to 200 with a JSON-encoded body
get "/json" do
%{"hyper" => "social"}
end
# Pattern match part of the path into a variable
get "/presenter/:name" do
"The presenter is #{name}"
end
import_routes Trot.NotFound
endTo add templating in a router, add use Trot.Template and set @template_root to the top-level directory containing your templates. By default, @template_root is "priv/templates/".
Trot can be used to render EEx templates (the default engine include with Elixir), HAML templates through Calliope, or a combination of both. When the application is compiled a render_template/2 function is generated for every template under @template_root. render_template/2 expects the name of the template relative to @template_root as the first argument and a keyword list of variables to assign as the second argument.
When MIX_ENV=prod all of templates are loaded and pre-compiled for faster rendering.
defmodule PiedPiper do
use Trot.Router
use Trot.Template
@template_root "priv/templates/root"
get "/compression/pied_piper" do
render_template("compression_results.html.eex", [weissman_score: 5.2])
end
get "/compression/nucleus" do
render_template("compression_results.html.haml", [weissman_score: 2.89])
end
end
# compression_results.html.eex
<html><body>Pied piper has a Weissman Score of <%= @weissman_score %></body></html>
# compression_results.html.haml
%html
%body Nucleaus has a Weissman Score of <%= @weissman_score %>The plug/2 macro is available within a Trot router, allowing any plug to be inserted into the pipeline. Anything after Trot.Router will likely have a closed connection, so most uses cases will involve pulling in Plug.Builder first.
defmodule SoLoMoApp.Router do
use Plug.Builder
plug Plug.RequestId
use Trot.Router
get "/hello", do: "hello"
endAdding use Trot.Versioning to your module will enable API version parsing and pattern matching. The first part of the path for all requests in the module is assumed to be the version. It is parsed into the conn[:assigns] dictionary, making it easy to access. Routes can also be configured to only match a particular version.
defmodule Nucleus do
use Trot.Router
use Trot.Versioning
get "/version" do
conn.assigns[:version]
end
get "/current", version: "v1" do
:ok
end
get "/current" do
:bad_request
end
endIn the above example, "/v1/version" will return "v1" as the response body. A request to "/v1/current" will return a 200 but "/v2/current" will return a 400.
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