如何从bot Emulator上传文件（.pdf，.jpg..jpeg）并转换为二进制（base64）而不将文件保存到本地驱动器？

Question

SDK Platform: Node.js

How can I upload file (.pdf,.jpg..jpeg) from bot Emulator and convert to binary (base64) without saving file into local drive.

Code Example:

var url = session.message.attachments[0].contentUrl;
var fileName=session.message.attachments[0].name;
var encodedData = new Buffer(fs.createWriteStream(url+"/"+fileName), 'binary').toString('base64');

something like above, but it is not working for me.

Expected Behavior:

We need to upload file from BOT emulator and convert file content into binary data.

Actual Result:

ERROR: ENOENT: no such file or directory, open 'D:\\User\\projects\\messages\\http:\\localhost:61058\\v3\\attachments\\ne1gmlim5kfg\\views\\original\\filename.pdf'

Here appending current directory which is not required.

For reference: https://github.com/Microsoft/BotBuilder/issues/3628

Answer 1

Here's an example of downloading a file and base64 encoding it in memory:

var bot = new builder.UniversalBot(connector, function (session) {
    var msg = session.message;
    if (msg.attachments.length) {

        // Message with attachment, proceed to download it.
        // Skype & MS Teams attachment URLs are secured by a JwtToken, so we need to pass the token from our bot.
        var attachment = msg.attachments[0];
        var fileDownload = checkRequiresToken(msg) ? requestWithToken(attachment.contentUrl) : request(attachment.contentUrl);

        fileDownload.then(
            function (response) {
                var base64String = new Buffer(response, 'binary').toString('base64');

                var echoImage = new builder.Message(session).text('You sent:').addAttachment({
                        contentType: attachment.contentType,
                        contentUrl: 'data:' + attachment.contentType + ';base64,' + base64String,
                        name: 'Uploaded Image'
                    });
                session.send(echoImage);

            }).catch(function (err) {
                console.log('Error downloading attachment:', { statusCode: err.statusCode, message: err.response.statusMessage });
            });
    } else {
        // No attachments were sent
        var reply = new builder.Message(session)
            .text('Hi there! This sample is intented to show how can I receive attachments but no attachment was sent to me. Please try again sending a new message with an attachment.');
        session.send(reply);
    }
});

// Request file with Authentication Header
var requestWithToken = function (url) {
    return obtainToken().then(function (token) {
        return request({
            url: url,
            headers: {
                'Authorization': 'Bearer ' + token,
                'Content-Type': 'application/octet-stream'
            }
        });
    });
};

// Promise for obtaining JWT Token (requested once)
var obtainToken = Promise.promisify(connector.getAccessToken.bind(connector));

var checkRequiresToken = function (message) {
    return message.source === 'skype' || message.source === 'msteams';
};

An entire project demonstrating this can be found here: https://github.com/nwhitmont/botframework-node-v3-receive-attachment