Bootstrap dropdown-toggle无法展开问题求助

问题根源 #

• Bootstrap版本属性不匹配：页面导航栏折叠按钮使用的是Bootstrap 5的data-bs-toggle属性，而下拉按钮仍用旧版的data-toggle，Bootstrap 5已将所有原生交互的data属性前缀统一为data-bs-，旧前缀无法触发下拉逻辑。
• HTML结构错误：下拉按钮的<a>标签被重复闭合，破坏了DOM结构，导致交互逻辑失效。
• 冗余元素：Bootstrap 5的dropdown-toggle类已自带下拉箭头样式，无需额外添加<span class="caret"></span>元素。

修复后的下拉菜单代码 #

<li class="nav-item dropdown">
    <a class="nav-link text-dark dropdown-toggle" 
       data-bs-toggle="dropdown" 
       role="button" 
       aria-expanded="false"
       asp-area="">Json</a>
    <ul class="dropdown-menu">
        <li><a class="dropdown-item text-dark" asp-area="" asp-page="LoadJson">Load Json</a></li>
        <li><a class="dropdown-item text-dark" asp-area="" asp-page="BulkLoadJson">Bulk Load Json</a></li>
    </ul>
</li>

完整修复后的页面代码 #

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>@ViewData["Title"] - DataMagnifierAdmin</title>
    <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.min.css" />
    <link rel="stylesheet" href="~/css/site.css" asp-append-version="true" />
    <link rel="stylesheet" href="~/DataMagnifier_Admin.styles.css" asp-append-version="true" />
</head>
<body>
    <header>
        <nav class="navbar navbar-expand-sm navbar-toggleable-sm navbar-light bg-white border-bottom box-shadow mb-3">
            <div class="container">
                <a class="navbar-brand" asp-area="" asp-page="/Index">DataMagnifierAdmin</a>
                <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target=".navbar-collapse" aria-controls="navbarSupportedContent"
                        aria-expanded="false" aria-label="Toggle navigation">
                    <span class="navbar-toggler-icon"></span>
                </button>
                <div class="navbar-collapse collapse d-sm-inline-flex justify-content-between">
                    <ul class="navbar-nav flex-grow-1">
                        <li class="nav-item">
                            <a class="nav-link text-dark" asp-area="" asp-page="/Index">Home</a>
                        </li>
                        <li class="nav-item">
                            <a class="nav-link text-dark" asp-area="" asp-page="ExecETL">Execute ETL</a>
                        </li>
                        <li class="nav-item dropdown">
                            <a class="nav-link text-dark dropdown-toggle" 
                               data-bs-toggle="dropdown" 
                               role="button" 
                               aria-expanded="false"
                               asp-area="">Json</a>
                            <ul class="dropdown-menu">
                                <li><a class="dropdown-item text-dark" asp-area="" asp-page="LoadJson">Load Json</a></li>
                                <li><a class="dropdown-item text-dark" asp-area="" asp-page="BulkLoadJson">Bulk Load Json</a></li>
                            </ul>
                        </li>
                        <li class="nav-item">
                            <a class="nav-link text-dark" asp-area="" asp-page="/Privacy">Privacy</a>
                        </li>
                    </ul>
                    <partial name="_LoginPartial" />
                </div>
            </div>
        </nav>
    </header>
    <div class="container">
        <main role="main" class="pb-3">
            @RenderBody()
        </main>
    </div>

    <footer class="border-top footer text-muted">
        <div class="container">
            &copy; 2022 - DataMagnifier_Admin - <a asp-area="" asp-page="/Privacy">Privacy</a>
        </div>
    </footer>

    <script src="~/lib/jquery/dist/jquery.min.js"></script>
    <script src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
    <script src="~/js/site.js" asp-append-version="true"></script>

    @await RenderSectionAsync("Scripts", required: false)
</body>
</html>

额外说明 #

• 下拉菜单内的链接改用dropdown-item类，这是Bootstrap 5的标准样式类，能更好适配下拉菜单的布局和交互，避免使用nav-link可能导致的样式冲突。
• 确认bootstrap.bundle.min.js已正确引入，该文件包含下拉功能依赖的Popper.js，无需单独引入Popper。

内容的提问来源于stack exchange，提问作者brad