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Multipart-POST Request Using Node.js

Multipart-POST Request Using Node.js

Here, I introduce 2 scripts for uploading files to Slack using Node.js as samples. These 2 sample scripts are for uploading files to Slack.

Sample script 1:

  • You can upload the zip file by converting byte array as follows.
    • At first, it builds form-data.
    • Adds the zip file converted to byte array and boundary using Buffer.concat().
    • This is used as body in request.

Basically, this is almost the same to the method using GAS.

var fs = require('fs');
var request = require('request');
var upfile = 'sample.zip';
fs.readFile(upfile, function(err, content){
    if(err){
        console.error(err);
    }
    var metadata = {
        token: "### access token ###",
        channels: "sample",
        filename: "samplefilename",
        title: "sampletitle",
    };
    var url = "https://slack.com/api/files.upload";
    var boundary = "xxxxxxxxxx";
    var data = "";
    for(var i in metadata) {
        if ({}.hasOwnProperty.call(metadata, i)) {
            data += "--" + boundary + "\r\n";
            data += "Content-Disposition: form-data; name=\"" + i + "\"; \r\n\r\n" + metadata[i] + "\r\n";
        }
    };
    data += "--" + boundary + "\r\n";
    data += "Content-Disposition: form-data; name=\"file\"; filename=\"" + upfile + "\"\r\n";
    data += "Content-Type:application/octet-stream\r\n\r\n";
    var payload = Buffer.concat([
            Buffer.from(data, "utf8"),
            new Buffer(content, 'binary'),
            Buffer.from("\r\n--" + boundary + "--\r\n", "utf8"),
    ]);
    var options = {
        method: 'post',
        url: url,
        headers: {"Content-Type": "multipart/form-data; boundary=" + boundary},
        body: payload,
    };
    request(options, function(error, response, body) {
        console.log(body);
    });
});

Sample script 2:

  • fs.createReadStream() can be used as a file for uploading to Slack.
var fs = require('fs');
var request = require('request');
request.post({
    url: 'https://slack.com/api/files.upload',
    formData: {
        file: fs.createReadStream('sample.zip'),
        token: '### access token ###',
        filetype: 'zip',
        filename: 'samplefilename',
        channels: 'sample',
        title: 'sampletitle',
    },
}, function(error, response, body) {
    console.log(body);
});

Result :

Both sample 1 and sample 2 can be uploaded zip file to Slack as follows. For both, even if filetype is not defined, the uploaded file is used automatically as a zip file.

@katio

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katio commented Dec 2, 2018

It works like charm. Thx. I just want to mention that Request is a external package: https://github.com/request/request#readme
So first:
npm install --save request

@abhishek200593

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abhishek200593 commented Aug 21, 2019

Hey I am confused about one thing, the boundary always be changes with each request, so how is it handled here?

@aravind1078

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aravind1078 commented Nov 7, 2019

Hey I am confused about one thing, the boundary always be changes with each request, so how is it handled here?

i guess it doesn't necessarily have to be different every-time you make a request

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