FileUpload.hasFile is always False

问题:

I have a FileUpload control (and it's not inside an UpdatePanel) and its hasFile property is always False.

   <asp:FileUpload ID="certificateUploader" runat="server"/>

Any thought?

回答1:

Add a trigger for your UpdatePanel

<Triggers>
   <asp:PostBackTrigger ControlID="btnCertificateUpload" />
</Triggers>

This will force a postback when the upload button is clicked.

Also add the line below to the Page_Load

Page.Form.Attributes.Add("enctype", "multipart/form-data");

回答2:

You cannot upload files using AJAX => you should not be placing a FileUpload control inside an UpdatePanel because this UpdatePanel sends an AJAX request to the server.

回答3:

I also uploaded a file using the FileUpload control, but the HasFile property returned false. Turn out that FileUpload.HasFile is also false if you upload an empty file. In this case adding some text to the file you want to upload will make the Hasfile property return true.

回答4:

To complement the example given by @dbFrameIT Support:

        <asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Always" runat="server">
            <ContentTemplate>
                <asp:FileUpload ID="FileUpload1" runat="server" />
                <asp:Button ID="UploadButton" runat="server" Text="Upload Selected File" OnClick="UploadButton_Click" />
                <asp:Label ID="UploadDetails" runat="server" Text=""></asp:Label>
            </ContentTemplate>
            <Triggers>
                <asp:PostBackTrigger ControlID="UploadButton" />
            </Triggers>
        </asp:UpdatePanel>

your code behind (c#)

    protected void UploadButton_Click(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile == false)
        {
            UploadDetails.Text = "Please first select a file to upload...";
        }
        else
        {
            string FileName = FileUpload1.FileName;
            UploadDetails.Text = string.Format(
                    @"Uploaded file: {0}<br />
              File size (in bytes): {1:N0}<br />
              Content-type: {2}",
                      FileName,
                      FileUpload1.FileBytes.Length,
                      FileUpload1.PostedFile.ContentType);

            // Save the file
            string filePath = Server.MapPath("~/Brochures/" + FileUpload1.FileName);
            FileUpload1.SaveAs(filePath);
        }
    }

回答5:

the whole time it was about the permissions i had(or didn't have to be more specific) over the file am trying to upload, i granted the user the sufficient permissions and it all went well.

thanks a lot for your help and posts.

回答6:

Sometimes fileUpload has problems. You can use simple input:

<input id="filMyFile" type="file" runat="server"></input>

In code save file to server:

HttpPostedFile myFile = filMyFile.PostedFile;           
string fullPath=Server.MapPath("~/UploadDocuments/") + myFile.FileName;
myFile.SaveAs(fullPath);

And file will save at UploadDocuments folder in your ASP.NET application (server)

回答7:

You can try to take your button off from the UpdatePanel; As far as I get, UpdatePanels always update when something inside any other update panel updates, so if your button postback, your FileUpload control also postback and lose the file reference.