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halo-dark-mode-plugin/.agents/skills/halo-theme-dev/references/thymeleaf-tips.md
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Serendipity edbf78f236 feat: 初始化 Halo 暗色模式插件
- Halo Plugin 后端(Java/Gradle),含 DarkModePlugin 主类和测试
- Vue 3 + TypeScript 前端 UI,包含主题切换组件和设置页面
- 暗色模式 CSS 变量和覆盖样式(布局/编辑器/表单/滚动条等)
- 设计文档和调查文档
- Halo 插件/主题开发 Agent Skills

Co-Authored-By: Claude <noreply@anthropic.com>
2026-08-06 21:03:00 +08:00

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2.3 KiB
Markdown

# Thymeleaf Best Practices for Halo Themes
**1. Prefer literal substitutions over string concatenation**
```html
<!-- ✅ readable, no quoting issues -->
<title th:text="|${post.spec.title} - ${site.title}|"></title>
<!-- ❌ verbose and error-prone -->
<title th:text="${post.spec.title} + ' - ' + ${site.title}"></title>
```
**2. Use safe navigation `?.` to avoid NullPointerException**
```html
<!-- ✅ returns null instead of throwing if target is null -->
<a th:target="${item.spec.target?.value}"></a>
```
**3. Use Elvis operator `?:` for default values**
```html
<p th:text="${theme.config.basic.custom_footer ?: site.title}"></p>
```
**4. Use `th:block` to group without adding extra DOM elements**
```html
<th:block th:each="archive : ${archives.items}">
<h2 th:text="${archive.year}"></h2>
<ul>
...
</ul>
</th:block>
```
**5. Use `th:classappend` for conditional classes**
```html
<!-- ✅ appends "active" without overwriting existing classes -->
<a th:classappend="${item.active} ? 'active'">...</a>
<!-- ❌ replaces all classes -->
<a th:class="${item.active} ? 'nav-link active' : 'nav-link'">...</a>
```
**6. Use `#lists.isEmpty()` and `#strings.isEmpty()` for null-safe checks**
```html
<div th:if="${not #lists.isEmpty(post.tags)}">
<a th:each="tag : ${post.tags}" th:text="${tag.spec.displayName}"></a>
</div>
```
**7. Do not manually add meta tags — Halo injects them automatically**
Only `<title>` needs to be in the theme. Halo automatically injects at runtime:
- `<meta name="description">` and `<meta name="keywords">`
- Open Graph tags (`og:title`, `og:description`, `og:image`, etc.)
- Twitter Card tags and canonical URL
```html
<!-- ✅ correct -->
<head>
<title th:text="${site.title}">Site Title</title>
</head>
<!-- ❌ redundant — conflicts with Halo's auto-injected tags -->
<head>
<title th:text="${site.title}">Site Title</title>
<meta name="description" th:content="${site.seo.description}" />
<meta property="og:title" th:content="${site.title}" />
</head>
```
**8. Use `@{${url}}` for dynamic permalink URLs**
```html
<!-- ✅ correct: wraps runtime URL in Thymeleaf's URL context -->
<a th:href="@{${post.status.permalink}}">...</a>
<!-- ❌ wrong: bypasses URL processing -->
<a th:href="${post.status.permalink}">...</a>
```