在 Microsoft Bot framework V4 中从 Bot 向用户发送 Excel 文件

Question

I am developing a Bot application using MS bot framework V4. I want to send Excel file (.xlsx) from Bot to the user, it is a template which user later fills in and send back to Bot. But with the following code, I can see the file in the chat window but user is not able to download the file. How can I achieve this functionality where user can download it. Note: Please see the ELSE part below where user is supposed to download the Excel template.

 private async Task<DialogTurnResult> UploadFileTemplateCheckStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
    {
        string choice = ((FoundChoice)stepContext.Result).Value;
        if (choice.ToLower().Equals("yes"))
        {
            stepContext.Values["IsFileTemplate"] = (string)stepContext.Result;
            return await stepContext.PromptAsync(nameof(TextPrompt), new PromptOptions
            { Prompt = MessageFactory.Text("Please upload the file.") }, cancellationToken);
        }
        else
        {
            //Provide the template.
            var ImagePath = Path.Combine(_env.WebRootPath, "TeeUpTemplate.xlsx");
            var ImageData = Convert.ToBase64String(File.ReadAllBytes(ImagePath));
            Attachment attachment = new Attachment()
            {
                Name = "TeeUpTemplate.xlsx", ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                ThumbnailUrl = Path.Combine(_env.WebRootPath, "Excel.png"),
                ContentUrl = $"data:application/vnd.ms-excel;base64,{ImageData}"
            };

            IMessageActivity reply = MessageFactory.Text("Use this template to fill the file.");
            reply.Attachments = new List<Attachment>();
            reply.Attachments.Add(attachment);
            reply.From = stepContext.Context.Activity.From;
            await stepContext.Context.SendActivityAsync(reply, cancellationToken);

            return await stepContext.PromptAsync(nameof(TextPrompt), new PromptOptions
            { Prompt = MessageFactory.Text("Upload the file") }, cancellationToken);
        }
    }

Answer 1

Here is the solution which I implemented. If your bot works with attachments then one of the method is One Drive subscription or sharepoint subscription. It is a mandate. I used One Drive subscription. All the attachment first gets uploaded or downloaded to your One Drive Account from where it goes to the bot.

The major drawback for developers is you can not test this in Bot Emulator, it has to be tested directly in Teams as Content Type = application/vnd.microsoft.teams.file.download.info only has support in Teams.

One more point is you will have to upload Manifest file with file with

"supportsFiles": true,

You may refer this sample for C# to get more insights:

https://github.com/microsoft/BotBuilder-Samples/tree/main/samples/csharp_dotnetcore/56.teams-file-upload

Thank you.