Templ Foundation

Templ Foundation

Overview

Sets up a Go project with templ - a type-safe HTML templating language that compiles to Go code.

Key Benefits:

• Type-safe templates with compile-time checks
• No runtime parsing overhead
• IDE autocompletion and refactoring
• Fast rendering (~2-3x faster than html/template)

When to Use

1. Starting new templ project or Go web app with server-side rendering
2. User explicitly mentions templ, type-safe templates, or Go HTML
3. Building hypermedia-driven apps (HTMX, etc.)
4. Creating templ feature in Doodle project

Quick Start (6 Steps)

1. Create Project Structure

mkdir project-name
cd project-name
mkdir -p components handlers static

2. Initialize Go Module

go mod init github.com/user/project-name
go get github.com/a-h/templ

3. Install Templ CLI

go install github.com/a-h/templ/cmd/templ@latest

# Verify
templ version

Troubleshooting: If templ: command not found, add to PATH:

export PATH=$PATH:$(go env GOPATH)/bin

4. Create First Component

Create components/hello.templ:

package components

templ Hello(name string) {
    <div>
        <h1>Hello, { name }!</h1>
    </div>
}

5. Generate Go Code

templ generate

This creates components/hello_templ.go with compiled Go code.

6. Use in Server

Create main.go:

package main

import (
    "net/http"
    "project-name/components"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        components.Hello("World").Render(r.Context(), w)
    })

    http.ListenAndServe(":8080", nil)
}

Run:

go run .

Visit http://localhost:8080

Core Workflow

Development Cycle

1. Write .templ component
2. Run templ generate (or watch mode)
3. Import generated component in Go code
4. Call .Render(ctx, writer) method

Development Modes

Option A: Manual (simple, no extra tools)

# Terminal 1
templ generate --watch

# Terminal 2
go run .

Option B: Air (auto-reload, recommended)

go install github.com/cosmtrek/air@latest
air

See build-makefile.md for task automation and build-air.md for live reload setup.

Project Structure

Choose structure based on project size:

Small (< 10 components):

project/
├── main.go
├── components/      # All templates (flat)
├── handlers/
└── static/

Medium (10-50 components):

project/
├── cmd/server/
├── internal/
│   ├── components/
│   │   ├── layout/      # Page layouts
│   │   ├── pages/       # Full pages
│   │   └── shared/      # Reusable UI
│   └── handlers/
└── static/

Large (50+ components):

project/
├── cmd/server/
├── internal/
│   ├── app/             # Business logic
│   └── web/
│       ├── components/
│       │   ├── auth/    # By domain
│       │   ├── products/
│       │   └── shared/
│       └── handlers/
└── static/

Migration path: Small → Medium (add folders) → Large (add domains)

Essential Files

go.mod

module github.com/user/project-name

go 1.21

require github.com/a-h/templ v0.2.543

.gitignore

# Generated files (NEVER commit)
*_templ.go

# Build artifacts
tmp/
dist/
*.exe

# IDE
.vscode/
.idea/
.DS_Store

Important: *_templ.go files are build artifacts. Never commit them.

IDE Setup

VS Code (recommended):

• Install extension: "templ" by a-h (ID: a-h.templ)
• Provides LSP, syntax highlighting, formatting

Other editors: GoLand, Neovim, Vim all support templ with plugins.

Common Issues

"templ: command not found"

Add $GOPATH/bin to PATH:

export PATH=$PATH:$(go env GOPATH)/bin

Generated files not found

Run templ generate before go run:

templ generate && go run .

Changes not reflecting

1. Check templ generate ran successfully
2. Verify *_templ.go file timestamp updated
3. Restart server (or use Air for auto-reload)

Import errors

Ensure module path matches:

// go.mod
module github.com/user/project

// Import as:
import "github.com/user/project/components"

Doodle Integration

For features/ directory:

cd features/
mkdir templ-blog
cd templ-blog

# Standard setup
go mod init github.com/homveloper/doodle/features/templ-blog
go get github.com/a-h/templ
mkdir -p components handlers static

# Create README following Doodle conventions
# Add to features/ tests if applicable

Best Practices

1. Never commit generated files: Add *_templ.go to .gitignore
2. Use watch mode: templ generate --watch in development
3. Start simple: Flat structure for small projects, grow as needed
4. Generate before build: CI/CD must run templ generate
5. Leverage type safety: Let compiler catch template errors

Next Steps

After foundation setup:

1. Learn syntax → templ-syntax skill
2. Build components → templ-components skill
3. HTTP integration → templ-http skill
4. Add interactivity → templ-htmx skill

References

Detailed guides (choose what you need):

• Build Tools:
  • Makefile: build-makefile.md - Task automation
  • Air: build-air.md - Live reload setup
• Project Structure:
  • Small (< 10 components): structure-small.md
  • Medium (10-50 components): structure-medium.md
  • Large (50+ components): structure-large.md

Assets

Template files for quick start:

• go.mod.template
• main.go.template
• Makefile
• .gitignore
• .air.toml.template

Focus: This skill covers project initialization only. For component writing, use templ-components. For server patterns, use templ-http.