Templates in Thymeleaf

Jan 17, 2024

Templates in Thymeleaf refer to reusable fragments of HTML or XML that can be included in multiple web pages to maintain consistency and reduce redundancy in web development. Thymeleaf is a server-side template engine that is commonly used in Spring applications, but it can be employed in various Java web frameworks. Templates allow you to define the structure and layout of your web pages, and then include these templates in different parts of your application.

Here's an explanation of templates in Thymeleaf:

Purpose of Templates:
- Templates help in keeping a consistent look and feel across your web application. They allow you to define common page structures, headers, footers, and other reusable components, reducing the need to duplicate code across multiple pages.
Template Structure:
- A Thymeleaf template is a regular HTML or XML file with placeholders, which are typically enclosed in curly braces {}. These placeholders are replaced with actual content when the template is rendered.
- Example of a simple Thymeleaf template:

<!DOCTYPE html>
<html>
<head>
    <title>My Template</title>
</head>
<body>
    <header>
        <h1 th:text="${pageTitle}">Default Page Title</h1>
    </header>
    <main>
        <div th:replace="fragments/menu :: menu"></div>
        <!-- Content goes here -->
    </main>
    <footer>
        &copy; 2023 My Company
    </footer>
</body>
</html>

Include and Replace:
- Thymeleaf provides two main mechanisms for including templates within other templates:
  - th:include: This attribute allows you to include another template within the current one. The included template can be inserted at a specified location.
  - th:replace: This attribute replaces the content of an element with the content of another template. This is useful for replacing entire sections of a page with dynamic content.
Passing Data:
- Templates often need dynamic data, such as page titles, menu items, or user-specific content. Thymeleaf allows you to pass data to templates by using the th:with attribute to set variables.
- Example of setting a variable and using it in a template:

<div th:with="pageTitle='My Page Title'">
    <h1 th:text="${pageTitle}">Default Page Title</h1>
</div>

Fragment Templates:
You can create fragment templates for reusable components, like navigation menus, sidebars, or cards. These fragments can be included in multiple pages using the th:replace or th:insert attributes.

Layouts:

A common use of templates in Thymeleaf is to define page layouts, which include header, footer, and sidebar components. Content-specific pages can then include these layout templates and provide the main content.

Incorporating Thymeleaf in Java Frameworks:

In Java web frameworks like Spring, Thymeleaf is often integrated as the view layer, allowing you to use templates to generate HTML responses. Thymeleaf templates can be combined with data from the backend to create dynamic web pages.

Templates in Thymeleaf promote code reusability and maintainability by separating the structure of a web page from its content. This approach simplifies the development and maintenance of web applications, making it easier to maintain a consistent user interface and reducing redundancy in your code.

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