c# - 如何在 asp.net web 表单中使用方法 ="post"的表单

Question

我正在使用 ajax 工具包 asyncFileUpload 控件

我有一个问题，我的服务器端事件没有触发，发现这个帖子 Hidden/Shown AsyncFileUpload Control Doesn't Fire Server-Side UploadedComplete Event

我在表单中插入了我的 uploader 并使用了这个属性 enctype="multipart/form-data"method="post"

这个 uploader 在我的网页表单中，它在母版页中

添加这个属性后我得到了这个错误

    A page can have only one server-side Form tag.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Web.HttpException: A page can have only one server-side Form tag.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 

这是我的网络表单

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    <form id="Form1" enctype="multipart/form-data" method="post" action="target_url"
    runat="server">
    <div id="Div1" runat="server">
        Just some time to make sure that the page doesn't get reloaded after uploading:
        <%=DateTime.Now %><br />
        <ajaxToolkit:AsyncFileUpload ID="FileUpload" runat="server" OnUploadedComplete="FileUpload_UploadCompleted"
            OnClientUploadComplete="FileUpload_ClientUploadCompleted" OnClientUploadError="uploadError"
            OnLoad="FileUpload_OnLoad" />
        <asp:Image runat="server" ID="imgUpload" src="" />
        <asp:Label runat="server" ID="lblerror" Text="" />
    </div>
    </form>
</asp:Content>

Answer 1

您的 MasterPage 已经有一个 form 元素。不允许嵌套的 form...

我不太了解 ajaxToolkit:AsyncFileUpload 但是，由于它是一个服务器控件，它应该更改父 form 的属性。您是否尝试过像下面的代码那样删除表单？

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    <div id="Div1" runat="server">
        Just some time to make sure that the page doesn't get reloaded after uploading:
        <%=DateTime.Now %><br />
        <ajaxToolkit:AsyncFileUpload ID="FileUpload" runat="server" OnUploadedComplete="FileUpload_UploadCompleted"
            OnClientUploadComplete="FileUpload_ClientUploadCompleted" OnClientUploadError="uploadError"
            OnLoad="FileUpload_OnLoad" />
        <asp:Image runat="server" ID="imgUpload" src="" />
        <asp:Label runat="server" ID="lblerror" Text="" />
    </div>
</asp:Content>

另一个可能的解决方案:

“弹出”一个“模态”表单，它只包含带有文件上传控件 的表单。这将解决嵌套表单问题。但是，它确实改变了功能。