Prism
A Ruby web framework, standard library only (socket, json, uri, cgi, digest, openssl, pstore, minitest). No bundler, no external gems. Started as a small Sinatra-style microframework and grew a controller layer, a file-backed ORM with migrations and associations, layouts/partials, flash messages, a static file server and a CLI generator on top of the original routing DSL, request/ response objects, middleware stack and its own HTTP/1.1 server.
Requirements
Ruby 3.3.x. This project targets the user-space build at ~/.local/ruby:
export PATH="$HOME/.local/ruby/bin:$PATH"
gem install sqlite3 does not work on every host (rubygems itself needs
psych, which needs libyaml headers that are not always installed). Prism
never depends on it: persistence is a real file-backed store built on the
standard library's PStore, described below.
Layout
lib/prism.rb top-level require aggregator
lib/prism/support/inflector.rb underscore/camelize/pluralize/tableize
lib/prism/params.rb indifferent-access params hash
lib/prism/template.rb ERB-like renderer with HTML escaping
lib/prism/view.rb file-based templates, layouts, partials
lib/prism/session.rb HMAC-SHA256 signed cookie encode/decode
lib/prism/flash.rb one-request-lifetime session flash
lib/prism/request.rb method, path, query, body, cookies, params
lib/prism/response.rb status, headers, body, cookies
lib/prism/router.rb PathMatcher, Route, Router, named routes
lib/prism/renderable.rb params/session/flash/render helpers shared
by Application and Controller
lib/prism/middleware.rb Rack-style middleware stack builder
lib/prism/middleware/logger.rb request logger
lib/prism/middleware/session.rb load/save session as signed cookie
lib/prism/middleware/static.rb static file server (with index.html support)
lib/prism/middleware/params.rb rejects malformed JSON bodies with 400
lib/prism/application.rb DSL, dispatch, filters, resources, url_for
lib/prism/controller.rb Controller base: actions, before/after_action
lib/prism/server.rb HTTP/1.1 server on TCPServer
lib/prism/orm.rb Prism::Orm.connect / .store / .transaction
lib/prism/orm/store.rb file-backed table store (PStore/Marshal)
lib/prism/orm/model.rb Model: CRUD, dynamic attributes, timestamps
lib/prism/orm/relation.rb where/order/limit/offset query builder
lib/prism/orm/validatable.rb presence/uniqueness/format/length validators
lib/prism/orm/associable.rb belongs_to / has_many
lib/prism/orm/migration.rb create_table/add_column DSL for migrations
lib/prism/orm/migrator.rb runs/rolls back migrations, tracks versions
lib/prism/orm/errors.rb per-attribute validation error collector
lib/prism/cli.rb Prism::Cli: new app / generate migration|model
bin/prism `prism new blog`, `prism generate model post ...`
examples/app.rb original Sinatra-style sample application
examples/blog/ full mini-Rails app: model+migration+
controller+views+sessions, scaffolded by
`Prism::Cli` itself
demo.rb boots examples/app.rb and hits it over HTTP
blog_demo.rb boots examples/blog and does a POST+GET
round trip through the ORM and the views
test/ minitest suite
Defining a Sinatra-style app
require 'prism'
class Blog < Prism::Application
enable_sessions(secret: 'change-me')
use Prism::Middleware::Logger
get '/' do
html('<h1>Prism</h1>')
end
get '/users/:id' do
json(id: params['id'])
end
get '/files/*' do
json(path: params['splat'])
end
group '/api' do
get '/status' do
json(ok: true)
end
end
post '/echo' do
json(received: params.to_h)
end
end
Params merge path, query and body (path wins). Template output is HTML-escaped
with <%= %>; use <%== %> for raw output.
Controllers, resources and views
class PostsController < Prism::Controller
layout :application
before_action :require_login, except: %i[index show]
def index
render(:index, locals: { posts: Post.order(:created_at, :desc) })
end
def create
post = Post.new(title: params['title'])
if post.save
flash[:notice] = 'Post created'
redirect url_for(:posts)
else
status(422)
render(:index, locals: { posts: Post.all, errors: post.errors.full_messages })
end
end
end
class Blog < Prism::Application
root(to: 'posts#index')
resources :posts, only: %i[index show create]
end
app/views/posts/index.erb is wrapped in app/views/layouts/application.erb
(the layout reads the rendered page through a local called content, not
Ruby's yield, since ERB templates are eval'd in a fresh binding rather than
inside the layout's own block). Partials live alongside the view they belong
to, prefixed with an underscore, and are called from inside a template with
partial('post', locals: { post: post }) or with a whole collection via
render_collection/Controller#render_each.
ORM-lite over a file-backed store
There is no SQLite dependency. Prism::Orm::Store persists tables to a single
file with PStore (Marshal under the hood), including multi-statement atomic
transactions with rollback on exception, and the data is still there the next
time a process opens the same file - see test/test_orm_store.rb's
test_data_survives_reopening_the_store and
test/test_integration_orm.rb's full HTTP round trip across two independent
servers.
Prism::Orm.connect('db/development.pstore')
Prism::Orm.migrator('db/migrate').migrate!
class Post < Prism::Orm::Model
validates :title, presence: true, length: { minimum: 3 }
belongs_to :author, class_name: 'User'
end
class User < Prism::Orm::Model
has_many :posts, foreign_key: 'author_id'
end
Post.where(title: 'Hello').order(:created_at, :desc).limit(10).offset(20)
Post.create(title: 'Hi').errors.full_messages
Migrations subclass Prism::Orm::Migration and implement up/down with a
create_table/add_column/remove_column/drop_table DSL; Migrator tracks
applied versions inside the store itself and supports migrate!/rollback!.
CLI generator
bin/prism new blog
cd blog
ruby -I../lib ../bin/prism generate model post title:string body:text
ruby -I../lib ../bin/prism generate migration add_published_to_posts
ruby bin/server 3000
prism new scaffolds app/{controllers,models,views}, db/migrate, a boot
file that connects the store and runs pending migrations, config.ru and a
bin/server script. generate model NAME field:type ... writes both the
model and a matching create_<table> migration; generate migration NAME on
its own writes an empty up/down skeleton (or a create_table skeleton if
the name starts with create_).
Running a server
server = Prism::Server.new(Blog, port: 0).start
puts server.url # http://127.0.0.1:<ephemeral-port>
# ...
server.stop
Port 0 asks the OS for a free ephemeral port, read back via server.port.
Tests
ruby -Itest -Ilib test/run_all.rb
or, with rake:
rake test
The suite covers routing (including named routes and resources), request
parsing, response building, the template and view engine, signed sessions and
flash, controllers and filters, the full ORM-lite stack (store, migrations,
models, validations, associations, the query builder, transactions), the
static file and JSON-body-guard middleware, the CLI generator (both in-process
and by shelling out to bin/prism), and HTTP integration tests that start the
server on an ephemeral port and drive it with Net::HTTP.
Demos
ruby demo.rb
ruby blog_demo.rb
demo.rb boots examples/app.rb (the original Sinatra-style sample) and
performs real HTTP requests. blog_demo.rb boots examples/blog (a real
generated app with a model, a migration, a controller and views), POSTs a new
post through the ORM and renders it back with the ERB view; the data stays on
disk in examples/blog/db/development.pstore after the process exits, so a
second run of the demo (or of any script that reconnects to that file) sees
the previously created posts.