grip

The microframework for writing powerful web applications.

Description

Grip is designed to be modular and easy to use, with the ability to scale up to the limits of the Crystal programming language. It offers extensibility and it has integrated middleware which alter the parts of the request/response context and pass it on to the actual endpoint, a filtering layer which was inherited from Kemal, an exception handling layer which represents a modified version of a Kemal exception handler and a router which somewhat resembles that of Phoenix framework's router.

Programming language: Crystal

License: MIT License

Tags: Web Frameworks    

Latest version: v4.0.4

README

The microframework for writing powerful web applications.

Grip is a microframework for building RESTful web applications. It is designed to be modular and easy to use, with the ability to scale up to the limits of the Crystal programming language. It offers extensibility and has integrated middleware called "pipes". Pipes can alter parts of the request/response context and then get passed to the actual endpoint. Grip's router is very similar to the router of the Phoenix framework. And most of all: Grip is fast.

Motivation

This project exists due to the fact that Kemal lacks one crucial part of a framework, a structure. An example for the absence of a structure can be found here.

Features

• HTTP 1.1 support.
• WebSocket RFC 6455 support.
• Built-in exceptions support.
• Parameter handling support.
• JSON serialization and deserialization support (fastest framework with JSON in Crystal).
• Middleware support.
• Request/Response context, inspired by expressjs.
• Advanced routing support.

Code example

Add this to your application's application.cr:

require "grip"

class IndexController < Grip::Controllers::Http
  def get(context : Context) : Context
    context
      .put_status(200) # Assign the status code to 200 OK.
      .json({"id" => 1}) # Respond with JSON content.
      .halt # Close the connection.
  end

  def index(context : Context) : Context
    id =
      context
        .fetch_path_params
        .["id"]

    # An optional secondary argument gives a custom `Content-Type` header to the response.
    context
      .json(content: {"id" => id}, content_type: "application/json; charset=us-ascii")
      .halt
  end

  def error(context : Context) : Context
    if context.request.path.includes?("/api/error")
      raise ArgumentError.new("An example message.")
    end

    context
      .json({"id" => UUID.random.to_s})
      .halt
  end
end

class ExceptionController < Grip::Controllers::Exception
  def call(context : Context) : Context
    context
      .json({"error" => context.exception.try(&.message)}) # The exception is nilable.
      .halt
  end
end

class Swigger::Swagger
  include HTTP::Handler

  def call(context : HTTP::Server::Context) : HTTP::Server::Context
    context
      .html("<h1>Hello, World!</h1>")
      .halt
  end
end

class PoweredByGrip
  include HTTP::Handler

  def call(context : HTTP::Server::Context) : HTTP::Server::Context
    context.put_resp_header("Server", "grip/#{Grip::VERSION}")

    context
  end
end

class Authorization
  include HTTP::Handler

  def call(context : HTTP::Server::Context) : HTTP::Server::Context
    raise Grip::Exceptions::Unauthorized.new unless context.get_req_header?("Authorization")

    context
  end
end

class Application < Grip::Application
  def initialize(environment : String, serve_static : Bool)
    # By default the environment is set to "development" and serve_static is false.
    super(environment, serve_static)

    exceptions [Grip::Exceptions::Unauthorized, Grip::Exceptions::NotFound], ExceptionController
    exception ArgumentError, ExceptionController

    pipeline :api, [PoweredByGrip.new, Authorization.new]
    pipeline :docs, [PoweredByGrip.new]

    scope "/api" do
      get "/error", IndexController, as: :error

      scope "/v1" do
        pipe_through :api

        get "/", IndexController
        get "/:id", IndexController, as: :index
      end
    end

    scope "/docs" do
      pipe_through :docs

      forward "/swagger", Swigger::Swagger
    end

    # Enable request/response logging.
    router.insert(0, Grip::Handlers::Log.new)
  end
end

app = Application.new(environment: "development", serve_static: false)
app.run

Installation

Add this to your application's shard.yml:

dependencies:
  grip:
    github: grip-framework/grip

And run this command in your terminal:

shards install

API Reference

Documentation can be found on the official website of the Grip framework.

Contribute

See our contribution guidelines and read the code of conduct.