CODEWITHSUNDEEP
node.js
Snowman
Snowman

Reputation: 2495

Downloading a zipped file from node writestream

I have a function fetching json data from postgres on click of a button. What I want is to save that data in a zipped file. I'm new to nodeJS, so I'm not entirely sure how writestreams and pipes work. This is what I have:

module.exports.fileDownload = function(req, res){
  var id = req.query.id;
  postgresService.getJsonData(id)
    .then(response => {
      const writer = fs.createWriteStream('my_file.json');

      // logger.info(response);
      // logger.info(writer);

      writer.write(response)

      res.pipe(writer);

    })
    .catch(err => {
      logger.info('Something went wrong');
      logger.info(err);

    })
}

I thought I'd figure out a way to use zlib once I at least get the file, but even at this stage, though my logger shows the response and the writer correctly, it ends up in the catch block. The error I keep seeing is:

TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be one of type string or Buffer

I should mention that the response is a fairly big json object.

I've played around with the code but can't get it to work. Some sources mention that you need to create a readstream to pipe to a writestream, but I'm not sure where in my code to do that.

Can anyone help?

Upvotes: 0

Views: 567

Answers (1)

Ashish Modi
Ashish Modi

Reputation: 7770

try this

module.exports.fileDownload = function(req, res){
  var id = req.query.id;
  postgresService.getJsonData(id)
    .then(response => {
      const writer = fs.createWriteStream('my_file.json');

      // logger.info(response);
      // logger.info(writer);

      writer.write(JSON.stringify(response));

      res.pipe(writer);

    })
    .catch(err => {
      logger.info('Something went wrong');
      logger.info(err);

    })
}

Basically you need to convert it to string so some other type as you wouldn't be able to write an object to write stream.

Upvotes: 1

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