kemalyst
Kemalyst
Kemalyst is a yarlf (yet another rails like framework) that is based on on super fast kemal. The framework leverages the http handlers which are similar to Rack middleware.
The router and controllers are an extension of the same middleware so you can chain any compatible HTTP::Handler before or after the routing handler so you can limit a particular handler to a sub-tree of your routes.
The model is a simple ORM mapping and supports MySQL, PG and SQLite.
The views are handled using kilt and several macros to simplify development.
Installation
- Install Crystal
You can find instructions on how to install Crystal from Crystal's Website.
- Install Kemalyst Generator
Kemalyst Generator is a command line tool similar to rails
.
brew tap drujensen/kgen
brew install kgen
- Initialize a new Kemalyst App using
kgen
kgen init app [your_app] -d [pg | mysql | sqlite] -t [slang | ecr] --deps
cd [your_app]
options: -d
defaults to pg. -t
defaults to slang. --deps
will run crystal deps
for you.
This will generate a traditional web application:
- /config - Application and HTTP::Handler config's goes here. The database.yml and routes.cr are here.
- /lib - shards are installed here.
- /public - Default location for html/css/js files. The static handler points to this directory.
- /spec - all the crystal specs go here.
- /src - all the source code goes here.
Usage
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 demo app locally:
- Create a new Postgres database called
[your_app]
- Run
export DATABASE_URL=postgres://[username]:[password]@localhost:5432/[your_app]
which exposes the database url toconfig/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 should be able to run:
docker-compose build
docker-compose up -d
docker-compose logs -f
Now you should be able to hit the site:
open "http://localhost:3000"
Docker Compose is running Sentry so
any changes to your /src
or /config
will re-build and run your
application.
Sample Applications
Several sample applications are provided:
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. Checkout
the samples that demonstrates a traditional blog site and a websocket chat
app.
Middleware HTTP::Handlers
There are 8 handlers that are pre-configured for Kemalyst:
- 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
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 the following methods: get, post, put, patch, delete, all
An example of a route would be:
get "/", DemoController::Index
You may chain multiple handlers in a route using an array:
get "/", [ BasicAuth.instance("username", "password"),
DemoController::Index.instance ]
or add them individually in the correct order:
get "/", BasicAuth.instance("username", "password")
get "/", DemoController::Index.instance
This is how you would configure a WebSocket Controller:
get "/", ChatController::Chat
get "/", ChatController::Index
See below for more information on how to create a WebSocket Handler.
You can use :variable
in the path and it will set a
context.params["variable"] to the value in the url.
get "/posts/:id", DemoController::Show
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 Post
include ActionHelper #adds in helper method "action"
action Index do
posts = Post.all("ORDER BY created_at DESC")
html render("post/index.ecr", "main.ecr")
end
end
Note: The above is shorthand for this:
require "../models/post"
class Index < Kemalyst::Controller
def call(context)
posts = Post.all("ORDER BY created_at DESC")
html render("post/index.ecr", "main.ecr")
end
end
There are several helper macros that set content type and response.
render "filename.ecr" # renders an .ecr template
render "filename.ecr", "layout.ecr" # renders an .ecr template with layout
redirect "path" # redirect to path
text "body", 200 # render text/plain with status code of 200
json "{}".to_json, 200 # render application/json with status code of 200
xml "{}".to_xml, 200 # render application/xml with status code of 200
html "<html></html>", 200 # render text/html with status code of 200
You can use the rendering engine to generate html
, json
, xml
or text
:
require "../models/post"
class Index < Kemalyst::Controller
def call(context)
posts = Post.all("ORDER BY created_at DESC")
json render("post/index.json.ecr")
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. If you include timestamps
, a created_at and updated_at field
mapping is created that follows the active_record convention in Rails.
You can also 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
There are several methods that are provided in the model.
- self.clear - "DELETE from table;"
- 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
@messages = [] of String
def call(socket : HTTP::WebSocket)
@sockets.push socket
socket.on_message do |message|
@messages.push message
@sockets.each do |a_socket|
a_socket.send @messages.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 a full example application, checkout Chat Kemalyst
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
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
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