Lapis

Lapis

A web framework for Lua or MoonScript

Install
luarocks install lapis
Reference Manual Source on GitHub
July 23rd, 2014: Lapis v1.0.3 is released, read more on the changelog

What is it?

Lapis is a framework for building web applications using MoonScript or Lua that runs inside of a customized version of Nginx called OpenResty.

Lua View examples in MoonScript

MoonScript View examples in Lua

local lapis = require "lapis"
local app = lapis.Application()

app:match("/", function(self)
  return "Hello world!"
end)

return app
lapis = require "lapis"

class extends lapis.Application
  "/": =>
    "Hello world!"

How does it work?

Lua is run directly inside of the Nginx worker, giving you the smallest barrier between the webserver and your code. OpenResty executes your Lua/MoonScript with LuaJIT, so it’s blazing fast. Have a look at Web Framework Benchmarks just to see how OpenResty stacks up against other platforms.

Nginx’s event loop is used for all asynchronous actions, including HTTP requests and database queries. With the power of Lua coroutines code is written synchronously but runs asynchronously, without all that callback spaghetti seen in other asynchronous platforms. It’s fast, easy to read, and easy to write.

Perform HTTP requests and other asynchronous operations freely without being concerned about blocking your application and killing your throughput.

×

What does it come with?

Lapis includes URL routing, HTML Templating, CSRF Protection and Session support, PostgreSQL backed models, schema generation and migrations in addition to a collection of useful functions needed when developing a website.

local lapis = require "lapis"
local app = lapis.Application()

-- Define a basic pattern that matches /
app:match("/", function(self)
  local profile_url = self:url_for("profile", {name = "leafo"})
  -- Use inline HTML helper to quickly write a template
  return self:html(function()
    h2("Welcome!")
    text("Go to my ")
    a({href = profile_url}, "profile")
  end)
end)

-- Define a named route pattern with a variable called name
app:match("profile", "/:name", function(self)
  return self:html(function()
    div({class = "profile"},
      "Welcome to the profile of " .. self.params.name)
  end)
end)

return app
lapis = require "lapis"

class extends lapis.Application
  -- Define a basic pattern that matches /
  "/": =>
    profile_url = @url_for "profile", name: "leafo"
    -- Use inline HTML helper to quickly write a template
    @html ->
      h2 "Welcome!"
      text "Go to my "
      a href: profile_url, "profile"

  -- Define a named route pattern with a variable called name
  [profile: "/:name"]: =>
    @html ->
      div class: "profile", ->
        text "Welcome to the profile of ", @params.name

Get a powerful abstraction layer over your database tables just by sub-classing Model:

local Model = require("lapis.db.model").Model

-- Create a model, backed by the table `users`
local Users = Model.extend("users")

-- fetch some rows from the table
local elderly_users = Users:select("where age > ? limit 5", 10)

local random_user = Users:find(1233) -- find by primary key

local lee = Users:find({
  name = "Lee",
  email = "leemiller@example.com"
})

-- create a new row and edit it
local user = Users:create({
  name = "Leaf",
  email = "leaf@example.com",
  age = 6
})

user:update({ age = 10 })

user:delete()
import Model from require "lapis.db.model"

-- Create a model, automatically backed by the table `users`
class Users extends Model

-- fetch some rows from the table
elderly_users = Users\select "where age > ? limit 5", 10

random_user = Users\find 1233 -- find by primary key

lee = Users\find name: "Lee", email: "leemiller@example.com"

-- create a new row and edit it
user = Users\create {
  name: "Leaf"
  email: "leaf@example.com"
  age: 6
}

user\update age: 10

user\delete!

Write your templates either in etlua or in pure Lua/MoonScript.

The template builder syntax works well in MoonScript and lets your organize your templates as classes, allowing you to use inheritance to mix and match methods as you see fit.

<h1 class="header"><%= "Hello" %></h1>
<% if current_user then %>
  <div class="user_panel">
    Welcome back <%= current_user.name %>
  </div>
<% end %>

<div class="body">
  Welcome to my site
</div>
import Widget from require "lapis.html"

class Index extends Widget
  content: =>
    h1 class: "header", "Hello"

    @user_panel!
    div class: "body", ->
      text "Welcome to my site!"

  user_panel: =>
    return unless @current_user
    div class: "user_panel", "Welcome back " .. @current_user.name

Using all the provided tools we can quickly and logically construct high performance and low memory web applications. Here’s a more complicated example complete with forms, CSRF protection, and various database queries.

local lapis = require "lapis"
local Model = require("lapis.db.model").Model
local capture_errors = require("lapis.application").capture_errors
local csrf = require "lapis.csrf"

local Users = Model:extend("users")

local app = lapis.Application()

app:before_filter(function(self)
  self.csrf_token = csrf.generate_token(self)
end)

app:get("list_users", "/users", function(self)
  self.users = Users:select() -- `select` all users
  return { render = true }
end)

app:get("user", "/profile/:id", function(self)
  local user = Users:find({ id = self.params.id })
  if not user then
    return { status = 404 }
  end

  return { render = true }
end)

app:post("/user/new", capture_errors(function(self)
  csrf.assert_token(self)
  Users:create({
    name = self.params.username
  })

  return { redirect_to = self:url_for("list_users") }
end))

app:get("new_user", "/user/new", function(self)
  return { render = true }
end)

return app
lapis = require "lapis"
import Model from require "lapis.db.model"
import respond_to, capture_errors from require "lapis.application"
csrf = require "lapis.csrf"

class Users extends Model

class extends lapis.Application
  -- Execute code before every action
  @before_filter =>
    @csrf_token = csrf.generate_token @

  [list_users: "/users"]: =>
    users = Users\select! -- `select` all the users

    -- Render HTML inline for simplicity
    @html ->
      ul ->
        for user in *users
          li ->
            a href: @url_for("user", user.id), user.name

  [user: "/profile/:id"]: =>
    user = Users\find id: @params.id
    return status: 404 unless user
    @html -> h2 user.name

  -- Respond to different HTTP actions to do the right thing
  [new_user: "/user/new"]: respond_to {
    POST: capture_errors =>
      csrf.assert_token @
      Users\create name: @params.username
      redirect_to: @url_for "list_users"

    GET: =>
      @html ->
        form method: "POST", action: @url_for("new_user"), ->
          input type: "hidden",
            name: "csrf_token", value: @csrf_token
          input type: "text", name: "username"
  }

Where can I learn more?

For a guide and tutorial to Lapis, consult the manual.

The source of Lapis can be found on Github and issues can be reported on the issues tracker.

MoonRocks is an open source application written in Lapis. It is a public Lua Rock repository and the source can be found on GitHub.

Anything else I should know?

You can deploy a new Lapis application in a few minutes.

If you don’t mind using Heroku then it’s just a matter of using the Lua Buildpack and installing the OpenResty module.

You can use most existing Lua libraries with Lapis with no problems. Here are some libraries you might find useful:

About

Lapis would not be possible without the following projects:

Lapis is licensed under the MIT license.

Lapis is written by @moonscript.

Reference Manual Source on GitHub
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