Overview

Want to Master Phoenix Through Working Code?

This guide teaches you Elixir Phoenix through 80+ production-ready code examples rather than lengthy explanations. If you’re an experienced developer switching to Phoenix, or want to deepen your framework mastery, you’ll build intuition through actual working patterns.

What Is By-Example Learning?

By-example learning is a code-first approach where you learn concepts through annotated, working examples rather than narrative explanations. Each example shows:

1. What the code does - Brief explanation of the Phoenix concept
2. How it works - A focused, heavily commented code example
3. Why it matters - A pattern summary highlighting the key takeaway

This approach works best when you already understand programming fundamentals. You learn Phoenix’s idioms, patterns, and best practices by studying real code rather than theoretical descriptions.

What Is Elixir Phoenix?

Phoenix is a web framework for Elixir that prioritizes developer productivity and application reliability. Key distinctions:

• Not Rails: Phoenix is more explicit and performant than Rails, designed for Erlang’s BEAM VM
• Real-time first: Built-in support for WebSockets, channels, and live updates (LiveView)
• Functional: Leverages Elixir’s functional paradigm for safer, more maintainable code
• Fault-tolerant: Supervision trees and process isolation provide resilience by default
• Modern: Phoenix 1.7+ includes verified routes, function components, and unified HEEx templates

Learning Path

  graph TD
  A["Beginner<br/>Core Phoenix Concepts<br/>Examples 1-25"] --> B["Intermediate<br/>Production Patterns<br/>Examples 26-50"]
  B --> C["Advanced<br/>Scale & Resilience<br/>Examples 51-80"]
  D["0%<br/>No Phoenix Knowledge"] -.-> A
  C -.-> E["95%<br/>Framework Mastery"]

  style A fill:#0173B2,color:#fff
  style B fill:#DE8F05,color:#000
  style C fill:#029E73,color:#fff
  style D fill:#CC78BC,color:#000
  style E fill:#029E73,color:#fff

Coverage Philosophy: 95% Through 80+ Examples

The 95% coverage means you’ll understand Phoenix deeply enough to build production systems with confidence. It doesn’t mean you’ll know every edge case or advanced feature—those come with experience.

The 80 examples are organized progressively:

• Beginner (Examples 1-25): Foundation concepts (routing, controllers, LiveView basics, Ecto fundamentals, forms, components)
• Intermediate (Examples 26-50): Production patterns (advanced LiveView, real-time features, authentication, testing, APIs)
• Advanced (Examples 51-80): Scale and resilience (database optimization, performance, deployment, monitoring, distributed systems)

Together, these examples cover 95% of what you’ll use in production Phoenix applications.

What’s Covered

Core Web Framework Concepts

• Routing & HTTP: Router pipelines, verified routes (~p sigil), REST resource definitions, controller actions
• Templates & Views: HEEx syntax, function components, slots, layout inheritance
• Request/Response: Conn manipulation, params handling, content negotiation, status codes
• Plugs & Middleware: Custom plugs, pipeline composition, authorization middleware

Real-Time & LiveView

• LiveView Lifecycle: Mount, render, handle_event, handle_params, socket assigns
• LiveView Components: Stateful vs function components, slots, event handling
• LiveView Features: Streams for efficient list updates, async operations, uploads, JS interop
• Phoenix Channels: Real-time bidirectional communication, presence tracking, PubSub

Data & Persistence

• Ecto Basics: Schemas, migrations, changesets, validation, CRUD operations
• Query Language: Pipe-based queries, associations, preloading, aggregations
• Advanced Patterns: Transactions, multi-tenancy, polymorphic associations, custom types
• Database: PostgreSQL features, query optimization, connection pooling

Security & Authentication

• Session-Based Auth: Login flows, password hashing, session management
• Token-Based Auth: JWT tokens, API authentication, token refresh
• Authorization: Role-based access control, permission checks, policy modules
• Third-Party Auth: OAuth2 integration, social login (Google, GitHub)

Testing & Quality

• Unit & Integration Tests: ConnCase, LiveView testing, mocking external services
• Test Fixtures: ExMachina factories, database seeds, test data
• Code Quality: Testing patterns, assertion helpers, debugging techniques

Production & Operations

• Deployment: Mix releases, Docker containerization, environment configuration
• Observability: Health checks, metrics collection (Telemetry), error tracking, structured logging
• Performance: Query optimization, caching strategies, background jobs (Oban), LiveDashboard
• Resilience: Rate limiting, circuit breakers, graceful shutdown, distributed Phoenix

What’s NOT Covered

We exclude topics that belong in specialized tutorials:

• Detailed Elixir syntax: Master Elixir first through language tutorials
• Advanced DevOps: Kubernetes, infrastructure-as-code, complex deployments
• Database-specific features: Deep PostgreSQL internals, advanced SQL optimization
• Language internals: BEAM scheduler details, memory management, Erlang distribution protocols
• Framework internals: How Phoenix processes requests internally, supervision tree architecture

For these topics, see dedicated tutorials and framework documentation.

How to Use This Guide

1. Choose Your Starting Point

• New to Phoenix? Start with Beginner (Example 1)
• Framework experience (Rails, Django, Spring)? Start with Intermediate (Example 21)
• Building specific feature? Search for relevant example topic

2. Read the Example

Each example has three parts:

• Explanation (2-3 sentences): What Phoenix concept, why it exists, when to use it
• Code (with heavy comments): Working Elixir code showing the pattern
• Key Takeaway (1-2 sentences): Distilled essence of the pattern

3. Run the Code

Create a test project and run each example:

mix phx.new my_app --no-ecto
cd my_app
# Paste example code
iex -S mix phx.server

4. Modify and Experiment

Change variable names, add features, break things on purpose. Experiment builds intuition faster than reading.

5. Reference as Needed

Use this guide as a reference when building features. Search for relevant examples and adapt patterns to your code.

Relationship to Other Tutorial Types

Prerequisites

Required

• Elixir fundamentals: Basic syntax, pipe operator, pattern matching, functional concepts
• Web development: HTTP basics, HTML, CSS, JavaScript fundamentals
• Programming experience: You’ve built applications before in another language

Recommended

• Erlang/OTP knowledge: Processes, message passing, supervision basics
• Relational databases: SQL basics, schema design, join concepts
• Git: Version control for managing code

Not Required

• Phoenix experience: This guide assumes you’re new to the framework
• Elixir expertise: We assume beginner-to-intermediate Elixir knowledge
• Web framework experience: Not necessary, but helpful

Structure of Each Example

All examples follow a consistent 4-part format:

### Example N: Descriptive Title

2-3 sentence explanation of the concept.

```elixir
# Heavily annotated code example
# showing the Phoenix pattern in action

Key Takeaway: 1-2 sentence summary.

**Code annotations**:

- `# =>` shows expected output or result
- Inline comments explain what each line does
- Variable names are self-documenting

**Mermaid diagrams** appear when visualizing flow or architecture improves understanding. We use a color-blind friendly palette:

- Blue #0173B2 - Primary
- Orange #DE8F05 - Secondary
- Teal #029E73 - Accent
- Purple #CC78BC - Alternative
- Brown #CA9161 - Neutral

## Ready to Start?

Choose your learning path:

- **[Beginner](/en/learn/software-engineering/web-platform/elixir-phoenix/tutorials/by-example/beginner)** - Start here if new to Phoenix. Build foundation understanding through 20 core examples.
- **[Intermediate](/en/learn/software-engineering/web-platform/elixir-phoenix/tutorials/by-example/intermediate)** - Jump here if you know Phoenix basics. Master production patterns through 20 examples.
- **[Advanced](/en/learn/software-engineering/web-platform/elixir-phoenix/tutorials/by-example/advanced)** - Expert mastery through 20 advanced examples covering scale, performance, and resilience.

Or jump to specific topics by searching for relevant example keywords (routing, authentication, LiveView, testing, deployment, etc.).