Computer Science A

Del Norte High School

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Week 18 Thymeleaf

Thymeleaf

1 min read • Week 18
  • Our Products

    • Thymeleaf Review

    What is Thymeleaf?

    • Server-side Java template engine
    • Natural templating - templates can be viewed as static prototypes
    • Integrates seamlessly with Spring Boot

    How is it useful?

    • Saves you a bunch of valuable time
    • Allows you to do much shorter lines/files that are simpler and complete the same tasks

    Basic Syntax:

    1. Namespace Declaration ```html
    ``` 2. Standard Expression Types ```html

    Placeholder text

    Placeholder text

    Link text

    Welcome message

    ``` ### Key Features - Layout dialects for template inheritance - Fragment inclusion - Conditional rendering - Form handling - Internationalization support # Basic Operations ### Form Handling ```html
    ``` ### Iteration ```html
    • Item name
    ``` ### Conditionals ```html

    User is an administrator

    User is a manager

    User is some other role

    ``` ### Fragment Inclusion ```html

    Common footer content

    ``` ## Mr. Mortensen's Example

    ## Example Task Create a Thymeleaf template that displays a list of products with their prices. Include a conditional to show a "Sale!" message if the price is below $50. ### Example Solution: ```html Product List

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    • Product Name $0.00 Sale!
    ``` ### Corresponding Controller: ```java @Controller public class ProductController { @GetMapping("/products") public String showProducts(Model model) { List products = productService.getAllProducts(); model.addAttribute("products", products); return "products"; } } ``` # Checklist to Maximize Success ✅ **Before Writing Templates** - Ensure proper namespace declaration - Understand the model attributes being passed from controller - Plan layout structure and reusable fragments **Writing Templates** - Use correct expression syntax (${}, @{}, *{}, #{}) - Handle null values appropriately - Implement proper error handling - Use th:with for complex expressions # Common Mistakes to Avoid ❌ ### Expression Syntax Confusion ${...} vs *{...}: - ${...}: Variable expressions (context variables) - *{...}: Selection expressions (selected object) ```html
    ``` ### Link URL Construction - Always use @{...} for URLs - Remember context path handling ```html Profile Profile ``` ### Fragment Inclusion - Proper syntax for fragment references - Correct parameter passing ```html
    ...
    ...
    ``` ### Common Runtime Errors - Not handling null values - Incorrect iteration variable scope - Missing model attributes - Invalid expression syntax