How to store continuous scale data in database


I have a very simple nodejs server (using Express) running locally on port 8000.
Using the npm package serialport I managed to connect to a scale and get it’s weight in a continuously mode like so.

terminal output..

50 stable
50 stable

I want to save the scale stable weight to a database (in my case MongoDB Atlas) but I don’t want to make hundreds of requests as the scale weight changes.

I know tools like RxJS and one of it’s operators distictUntilChange but I’m not using any client.

How this can be done working only with a server ?


Since you haven’t shown any code, here’s a conceptual answer, which assumes that your readings are coming from an async iterator and that you already have a function for uploading each weight value. In this example, the weight property of each reading is a number and the stable property of each reading is a nullish boolean.

async function uploadLoop (scaleReaderIterator, uploadWeight) {
  let previousWeight;

  for await (const {weight, stable} of scaleReaderIterator) {
    if (
      !stable || // the weight reading isn't stable, OR
      weight === previousWeight // the weight hasn't changed since last time
    ) continue; // don't do anything else in this code block
    // else

    // update the previous value
    previousWeight = weight;
    // upload it
  } // loop

Answered By – jsejcksn

This Answer collected from stackoverflow, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0

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