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Hanami Framework Cheatsheet

A quick reference guide to the Hanami framework, covering essential commands, configurations, and concepts for building robust web applications.

Project Setup & Core Concepts

Project Initialization

Creating a new Hanami project:

hanami new my_project
cd my_project

This command generates a basic Hanami project structure.

Starting the development server:

bundle exec hanami dev

Launches the Hanami development server, usually on localhost:2300.

Project Structure Overview:

  • apps/: Contains individual Hanami applications (e.g., web).
  • config/: Configuration files for the entire project.
  • db/: Database-related files (migrations, schema).
  • lib/: Core application logic and entities.

Application Architecture

Slice

A modular component encapsulating specific functionality within an application.

Actions

Handle incoming HTTP requests and orchestrate the response. Similar to controllers in other frameworks.

Views

Responsible for rendering the response. They prepare data for templates.

Repositories

Interact with the database. Provide an abstraction layer for data access.

Entities

Represent domain objects. They encapsulate data and business logic.

Routing & Controllers (Actions)

Defining Routes

Basic Route Definition:

Inside config/routes.rb:

slice :main, at: "/" do
  get "/", to: "home#index"
end

This maps a GET request to / to the index action of the HomeController.

Route Shorthands:

get "/articles", to: "articles.index"
post "/articles", to: "articles.create"
put "/articles/:id", to: "articles.update"

delete "/articles/:id", to: "articles.destroy"

Resources:

resources :articles

Automatically generates routes for common CRUD operations.

Creating Actions

Action Class Structure:

# in apps/web/controllers/home/index.rb
module Web::Controllers::Home
  class Index
    include Web::Action

    def call(params)
      # params contains request parameters
      # Perform logic here

      # Set response data
      @message = "Hello, Hanami!"
    end
  end
end

Exposing Data to Views:

Instance variables set in the call method are automatically available in the corresponding view.

Handling Parameters:

Request parameters are accessible through the params object.

Views & Templates

View Components

Basic View Structure:

# in apps/web/views/home/index.rb
module Web::Views::Home
  class Index
    include Web::View

    def message
      raw(context[:message])
    end
  end
end

Templates:

Located in apps/web/templates/home/index.html.erb (or other template engines).

Access data exposed by the view using instance variables or the context.

Partials:

Create reusable template snippets.

<%= partial 'shared/footer' %>

Template Engines

ERB

Embedded Ruby, the default template engine.

Slim

A fast and lightweight template engine with a clean syntax.

Haml

Another popular template engine with a concise syntax.

Models & Repositories

Defining Entities

Entity Structure:

# in lib/my_project/entities/article.rb
class Article < Hanami::Entity
end

Entities represent domain objects. They encapsulate data and business logic.

Attributes:

Attributes are defined through database schema.

Example: :id, :title, :content

Repositories

Repository Structure:

# in lib/my_project/repositories/article_repository.rb
class ArticleRepository < Hanami::Repository
end

Common Operations:

  • ArticleRepository.new.find(id): Finds an entity by ID.
  • ArticleRepository.new.create(data): Creates a new entity.
  • ArticleRepository.new.update(id, data): Updates an existing entity.
  • ArticleRepository.new.delete(id): Deletes an entity.

Querying:

ArticleRepository.new.where(title: 'Example').all
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