kemalyst
Kemalyst
Kemalyst is a yarlf (yet another rails like framework) that is based on super fast kemal. The framework leverages http handlers which are similar to Rack middleware.
Kemalyst follows the MVC pattern:
- Models are a simple ORM mapping and supports MySQL, PG and SQLite.
- Views are handled using kilt which support ECR (Erb like), SLang (Slim like), Crustache (Mustache like) or Temel (not sure what it's like).
- Controllers are http handlers that continue the chain of handlers after the routing takes place.
Kemalyst also supports:
- WebSockets provide two way communication for webapps that need dynamic updates
- Mailers render and deliver email via smtp.cr
- Jobs perform background tasks using sidekiq.cr
- Migrations provide ability to maintain your database schema's using Micrate
Kemalyst also comes with a command line tool similar to rails
called kgen
to help you get started quickly.
Installation
Brew
- Install Crystal
brew update
brew install crystal-lang
- Install Kemalyst Generator
brew tap kemalyst/kgen
brew install kgen
Linux / Ubuntu
- Install Crystal
curl https://dist.crystal-lang.org/apt/setup.sh | sudo bash
sudo apt-get update
sudo apt-get install build-essential crystal
-
Find the latest version of kgen at https://github.com/kemalyst/kemalyst-generator/releases
-
Run the following. Make sure to update the version number to the latest:
export KGEN_VERSION=0.6.1
curl -L https://github.com/kemalyst/kemalyst-generator/archive/v$KGEN_VERSION.tar.gz | sudo tar xvz -C /usr/local/share/. && cd /usr/local/share/kemalyst-generator-$KGEN_VERSION && sudo crystal deps && sudo make
sudo ln -sf /usr/local/share/kemalyst-generator-$KGEN_VERSION/bin/kgen /usr/local/bin/kgen
- Verify:
kgen --version
Initialize
Create a new Kemalyst App using kgen
kgen init app [your_app] [options]
cd [your_app]
There are several options:
- -d [pg | mysql | sqlite] - defaults to pg
- -t [slang | ecr] - defaults to slang
- --deps - install dependencies quickly. This is the same as running
shards install
This will generate a traditional web application:
- /config - The
database.yml
androutes.cr
are here. - /lib - shards (similar to gems in rails) are installed here.
- /public - Default location for html/css/js files.
- /spec - all the crystal specs go here.
- /src - all the source code goes here.
Generators
kgen generate
provides several generators:
- scaffold [name] [fields]
- model [name] [fields]
- controller [name] [methods]
- mailer [name] [fields]
- job [name] [fields]
- migration [name]
An example to generate scaffolding for a resource:
kgen generate scaffold Post name:string body:text draft:bool
This will generate scaffolding for a Post:
- src/controllers/post_controller.cr
- src/models/post.cr
- src/views/post/*
- db/migrations/[datetimestamp]_create_post.sql
- spec/controllers/post_controller_spec.cr
- spec/models/post_spec.cr
- appends route to config/routes.cr
- appends navigation to src/layouts/_nav.slang
Run Locally
To test the app locally:
- Create a new database called
[your_app]
in the db you chose. - Run
export DATABASE_URL=postgres://[username]:[password]@localhost:5432/[your_app]
or update the database url inconfig/database.yml
. - Migrate the database:
kgen migrate up
. You should see output likeMigrating db, current version: 0, target: [datetimestamp] OK [datetimestamp]_create_shop.sql
- Run the specs:
crystal spec
- Start your app:
kgen watch
- Then visit
http://0.0.0.0:3000
Note: The kgen watch
command uses Sentry to watch for any changes in your source files, recompiling automatically.
If you don't want to use Sentry, you can compile and run manually:
- Build the app
crystal build --release src/[your_app].cr
- Run with
./[your_app]
- Visit
http://0.0.0.0:3000
Run with Docker
Another option is to run using Docker. A Dockerfile
and docker-compose.yml
is provided. If
you have docker setup, you can run:
docker-compose up
Now visit the site:
open "http://localhost:3000"
Docker Compose is running Sentry as well so
any changes to your /src
or /config
will re-build and run your
application.
Configure App
All config settings are in the /config
folder. Each handler has its own
settings. You will find the database.yml
and routes.cr
here.
Router
The router will perform a lookup based on the method and path and return the
chain of handlers you specify in the /config/routes.cr
file.
You can use any of these simplified macros: get, post, patch, delete, all
get "/", home, index
Or you can specify the class directly:
get "/", HomeController::Index
You can use :variable
in the path and it will set a
context.params["variable"] to the value in the url.
get "/posts/:id", demo, show
You may chain multiple handlers in a route:
get "/", BasicAuth.instance("username", "password")
get "/", home, index
Resource Routes
You can declare RESTful routes by using resources
or resource
:
For multiple resources:
resources Demo
is the same as:
get "/demos", demo, index
get "/demos/new", demo, new
post "/demos", demo, create
get "/demos/:id", demo, show
get "/demos/:id/edit", demo, edit
patch "/demos/:id", demo, patch
delete "/demos/:id", demo, delete
For a single resource:
resource Demo
is the same as:
get "/demo/new", demo, new
post "/demo", demo, create
get "/demo", demo, show
get "/demo/edit", demo, edit
patch "/demo", demo, update
delete "/demo", demo, delete
There is also the ability to specify a before_resources
and before_resource
:
before_resources Demo, session, authenticate
Controllers
The Controller inherits from HTTP::Handler which is the middleware similar to Rack's middleware. The handlers are chained together in a linked-list and each will perform some action against the HTTP::Server::Context and then call the next handler in the chain. The router will continue this chain for a specific route. The final handler should return the generated response that will be returned as the body and then the chain will unwind and perform post handling.
An example of a controller:
require "../models/post"
module PostController
class Index < Kemalyst::Controller
def call(context)
posts = Post.all("ORDER BY created_at DESC")
html render("post/index.ecr", "main.ecr")
end
end
end
There are several helper macros that will set the content type and responses status:
redirect "path" # redirect to path
html "<html></html>", 200 # content type `text/html` with status code of 200
text "text", 200 # content type `text/plain` with status code of 200
json "{}".to_json, 200 # content type `application/json` with status code of 200
xml "{}".to_xml, 200 # content type `application/xml` with status code of 200
There are two render methods that will generate a string that can be passed to the above macros:
render "filename.ecr" # renders an .ecr template
render "filename.ecr", "layout.ecr" # renders an .ecr template with layout
You can use the rendering engine to generate html
, json
, xml
or text
:
require "../models/post"
module HomeController
class Index < Kemalyst::Controller
def call(context)
posts = Post.all("ORDER BY created_at DESC")
json render("post/index.json.ecr")
end
end
end
Views
Views are rendered using Kilt. Currently,
there are 4 different templating languages supported by Kilt: ecr
, mustache
,
slang
and temel
. Kilt will select the templating engine based on the
extension of the file so index.ecr
will render the file using the ECR
engine.
The render method is configured to look in the "src/views" path to keep the controllers simple. You may also render with a layout which will look for this in the "src/views/layouts" directory.
html render "post/index.ecr", "main.ecr"
This will render the index.ecr template inside the main.ecr layout. All local variables assigned in the controller are available in the templates.
An example views/post/index.ecr
:
<% posts.each do |post| %>
<div>
<h2><%= post.name %></h2>
<p><%= post.body %></p>
<p>
<a href="/posts/<%= post.id %>">read</a>
| <a href="/posts/<%= post.id %>/edit">edit</a> |
<a href="/posts/<%= post.id %>?_method=delete" onclick="return confirm('Are you sure?');">delete</a>
</p>
</div>
<% end %>
And an example of views/layouts/main.ecr
:
<!DOCTYPE html>
<html>
<head>
<title>Example Layout</title>
<link rel="stylesheet" href="/stylesheets/main.css">
</head>
<body>
<div class="container">
<div class="row">
<% context.flash.each do |key, value| %>
<div class="alert alert-<%= key %>">
<p><%= value %></p>
</div>
<% end %>
</div>
<div class="row">
<div class="col-sm-12">
<%= content %>
</div>
</div>
</div>
</body>
</html>
The <%= content %>
is where the template will be rendered in the layout.
CSRF middleware is built in. In your forms, add the csrf_tag
using the helper method:
<form action="/demos/<%= demo.id %>" method="post">
<%= csrf_tag(context) %>
...
</form>
Models
The models are a simple ORM mechanism that will map objects to rows in the database. The mapping is done using several macros.
An example models/post.cr
require "kemalyst-model/adapter/pg"
class Post < Kemalyst::Model
adapter pg
field name : String
field body : Text
field published : Bool
timestamps
end
The mapping will automatically create the id of type Int64. If you include timestamps
, a created_at and updated_at field
mapping is created that will automatically get updated for you.
You can override the table name:
require "kemalyst-model/adapter/pg"
class Comment < Kemalyst::Model
adapter pg
table_name post_comments
field post_id : Int64
field name String
field body : Text
end
You can override the id
field:
require "kemalyst-model/adapter/pg"
class Comment < Kemalyst::Model
adapter pg
primary my_id : Int32
...
end
There are several methods that are provided in the model.
- self.clear - "DELETE from table;" that will help with specs
- save - Insert or update depending on if id is set
- destroy(id) - "DELETE FROM table WHERE id = #{id}"
- all(where) "SELECT * FROM table #{where};"
- find(id) - "SELECT * FROM table WHERE id = #{id} LIMIT 1;"
- find_by(field, value) - "SELECT * FROM table WHERE #{field} = #{value} LIMIT 1;"
You can find more details at Kemalyst Model
WebSocket Controllers
The WebSocket Controller will handle upgrading a HTTP Request to a WebSocket Connection.
An example WebSocket Controller:
class Chat < Kemalyst::WebSocket
@sockets = [] of HTTP::WebSocket
def call(socket : HTTP::WebSocket)
@sockets.push socket
socket.on_message do |message|
@sockets.each do |a_socket|
a_socket.send message.to_json
end
end
end
end
The Chat
class will override the call
method that is expecting an
HTTP::WebSocket
to be passed which it would maintain and properly handle
messages to and from each socket.
This class will manage an array of HTTP::Websocket
s and configures the
on_message
callback that will manage the messages that will be then be
passed on to all of the other sockets.
It's important to realize that if the request is not asking to be upgraded to a websocket, it will call the next handler in the path. If there is no more handlers configured, a 404 will be returned.
Here is an example routing configuration:
get "/", ChatController::Chat
get "/", ChatController::Index
The first one is a WebSocket Controller and the second is a standard Controller. If the request is not a WebSocket upgrade request, it will pass-through and call the second one that will return the html page.
To see an example application, checkout Chat Kemalyst
Mailers
Kemalyst provides the ability to generate mailers:
kgen g mailer Welcome email:string name:string
This will generate the following files:
- config/mailer.yml
- spec/mailers/welcome_mailer_spec.cr
- src/mailers/welcome_mailer.cr
- src/views/layouts/mailer.slang
- src/views/mailers/welcome_mailer.slang
The mailer has the ability to set the from
, to
, cc
, bcc
, subject
and body
.
You may use the render
helper to create the body of the email.
class WelcomeMailer < Kemalyst::Mailer
def initialize
super
from "Kemalyst", "info@kemalyst.com"
end
def deliver(name: String, email: String)
to name: name, email: email
subject "Welcome to Kemalyst"
body render("mailers/welcome_mailer.slang", "mailer.slang")
super()
end
end
To delivery a new email:
mailer = WelcomeMailer.new
mailer.deliver(name, email)
You can deliver this in the controller but you may want to do this in a background job.
Jobs
Kemalyst provides a generator for with integration user sidekiq.cr for background jobs:
kgen g job Welcome name:string email:string
This will generate:
- config/sidekiq.cr
- docker-sidekiq.yml
- spec/jobs/spec_helper.cr
- spec/jobs/welcome_job_spec.cr
- src/jobs/welcome_job.cr
- src/sidekiq.cr
Jobs are using sidekiq.cr
for handling the background process. Sidekiq uses redis
to handle the queues and spins up several fibers to handle processing each job from the queue.
You will either need to install redis
locally or you can use the docker-sidekiq.yml
which is a pre-configured docker-compose file that will spin up the needed services.
To install redis locally and start the service:
brew install redis
brew services start redis
Sidekiq is expecting two environment variables to be configured:
export REDIS_PROVIDER = REDIS_URL
export REDIS_URL = redis://localhost:6379
Then you can start and watch the sidekiq service using kgen
:
kgen sidekiq
This will watch for any changes to the jobs and recompile and launch sidekiq.
Or you can compile and run the sidekiq.cr manually:
crystal build --release src/sidekiq.cr
./sidekiq
Here is an example background job that will deliver the email we created earlier:
require "sidekiq"
require "../mailers/welcome_mailer"
class WelcomeJob
include Sidekiq::Worker
def perform(name : String, email : String)
mailer = WelcomeMailer.new
mailer.deliver(name: name, email: email)
end
end
To execute the job, in your controller call:
WelcomeJob.async.perform(name, email)
docker-sidekiq.yml
If you have docker installed, you can spin up all of the services needed with:
docker-compose -f docker-sidekiq.yml up
This will spin up the following containers:
- web: your web application using the command
kgen watch
- sidekiq: sidekiq service using the command
kgen sidekiq
- migrate: runs the migration scripts using the command
kgen migrate up
- sidekiqweb: web interface to manage the sidekiq queues at http://localhost:3001
- mail: mail catcher smtp service on port 1025. You can view the email at http://localhost:1080
- redis: runs a redis instance version 3.2 on port 6379
- db: Mysql on port 3306 or Postgres on port 5432. Sqlite doesn't need a db since it file based.
Validation
Another Library included with Kemalyst is validation of your models. You can find more details at Kemalyst Validators
i18n Support
TechMagister has created a HTTP::Handler that will integrate his i18n library. You can find more details at Kemalyst i18n
Middleware HTTP::Handlers
There are 8 handlers that are pre-configured for Kemalyst. This is similar in architecture to Rack Middleware:
- Logger - Logs all requests/responses to the logger configured.
- Error - Handles any Exceptions and renders a response.
- Static - Delivers any static assets from the
./public
folder. - Session - Provides a Cookie Session hash that can be accessed from the
context.session["key"]
- Flash - Provides flash message hash that can be accessed from the
context.flash["danger"]
- Params - Unifies the parameters into
context.params["key"]
- CSRF - Helps prevent Cross Site Request Forgery.
- Router - Routes requests to other handlers based on the method and path.
Other handlers available for Kemalyst:
- CORS - Handles Cross Origin Resource Sharing.
- BasicAuth - Provides Basic Authentication.
You may want to add, replace or remove handlers based on your situation. You can do that in the
Application configuration config/application.cr
:
Kemalyst::Application.config do |config|
# handlers will be chained in the order provided
config.handlers = [
Kemalyst::Handler::Logger.instance,
Kemalyst::Handler::Error.instance,
Kemalyst::Handler::Params.instance,
Kemalyst::Handler::CORS.instance,
Kemalyst::Handler::Router.instance
]
end
Acknowledgement
Kemalyst is only possible with the use and help from many other crystal projects and developers. Special thanks to you and your contributions!
-
First and foremost the Crystal Team.
-
Kemal Originally forked from here - Serdar Dogruyol
-
spec-kemal - Kemal Spec for easy testing Serdar Dogruyol
-
Kilt Rendering templates - Jerome Gravel-Niquet
-
Slang Slim-inspired templating language - Jerome Gravel-Niquet
-
Radix Router is mostly copied from here - Luis Lavena
-
smtp.cr SMTP Client for mailers - Rayner De Los Santos F.
-
crystal-db Common database driver - Brian J. Cardiff
-
crystal-sqlite Sqlite Driver - Brian J. Cardiff
-
crystal-mysql Mysql Driver - Brian J. Cardiff
-
crystal-pg Postgres Driver - Will Leinweber
-
sidekiq.cr Sidekiq - Mike Perham
For Kemalyst Generator
- mocks Mocking Library - Oleksii Fedorov
- Crystal CLI CLI Library - mosop
- Teeplate Template Rendering Library - mosop
- ICR Interactive Crystal - Sergey Potapov
- Sentry Watch files, recompile and run - Sam Eaton
- Micrate Rails like Migration Tool - Juan Edi
Contributing
- Fork it ( https://github.com/drujensen/kemalyst/fork )
- Create your feature branch (git checkout -b my-new-feature)
- Commit your changes (git commit -am 'Add some feature')
- Push to the branch (git push origin my-new-feature)
- Create a new Pull Request
Contributors
- drujensen Dru Jensen - creator, maintainer
- TechMagister Arnaud Fernandés - contributor
- elorest Isaac Sloan - contributor