node.js async/await function called multiple times (before it ends)

Question

My main file is a "file watcher" that's watching a folder using "node-watch" module. For each file placed in the folder, it has to do couple of MSSQL calls and then process the file accordingly. The file watcher script looks like that:

var watch = require('node-watch');
const timestamp = require('./SHR_modules/timestamp');
const sql = require('./SHR_modules/sql');
const configuration = require('./SHR_modules/config');
const logger = require('./SHR_modules/logger');

watch('./Incoming', { recursive: true }, async function (evt, name) {

  if (evt == 'update') {
    logger.addLog(configuration.logFile.watcher, 'File found: ' + name);
    var startTime = await timestamp.dateTimeDelimited();                //capture time at proicessing start
    filePath = await name.replace(name.split('\\')[name.split('\\').length-1], '');
    fileName = await name.replace(filePath, '');
    var myLoad = await sql.readLoadSpec(fileName, filePath).catch(err => {
      logger.addLog(configuration.logFile.error, 'Error while reading Load Specs for file: ' + name);
      logger.addLog(configuration.logFile.error, err);
    });
    if (typeof myLoad !== 'undefined' && myLoad){
      console.log(evt);
      logger.addLog(configuration.logFile.watcher, 'Finished processing: ' + name);
    };
    var finishTime = await timestamp.dateTimeDelimited();                  //capture time at processing finish
  }
  else {
    logger.addLog(configuration.logFile.watcher, 'File removed: ' + name);
  }
  console.log(startTime);
  console.log(finishTime);
});

and the SQL function:

var readLoadSpec =  (fileName, filePath) => {
    return new Promise(async (resolve, reject) => {
        specIDs = await findSpecs(fileName, filePath)
        .catch(err => {
            reject(err);
            console.log(fileName + ' not found')
        });
        if (typeof specIDs !== 'undefined' && specIDs) {
            console.log('FOUND!!!!');
            var addLoadSpec = [];
            for (let i = 0; i < specIDs.length; i++) {
                console.log(specIDs);
                var tempQuery1 = `select * from LoadSpec where LoadID = ${specIDs[i]}`;
                var tempQuery2 = `select * from Mappings where LoadID = ${specIDs[i]} ORDER BY OutputColumn`;
                console.log(specIDs);     <========= code work sup to this line
                const results = await queryDB(tempQuery1);
                const resultsMapping = await queryDB(tempQuery2);
                console.log(fileName);
                console.log(results.recordset[0].OutputFileName);
                console.log(specIDs);
                const inputFrmt = {
                    name: results.recordset[0].InputFormatName,
                    format: results.recordset[0].InputFormat,
                    delimiter: results.recordset[0].InputDelimiter,
                    headerRows: results.recordset[0].InputHeaderRows
                };
.
.
.
                console.log(results.recordset[0].OutputColumnCount);
                addLoadSpec.push(loadSpec);
            };
            resolve(addLoadSpec);
        };
    });
};

So the code runs to the row I've marked (before the await for query results) and the loops back to beginning. So all is fine if I drop a single file into the folder, but when multiple files arrive at more or less the same time, the syncIDs var takes value of another file, before the code resumes after the query await part is completed. syncIDs is just an array so let's say for file 'a.csv' it's [1,2], for file 'b.csv' it's [3,4] and for file 'c.csv' it's undefined. So before it get's the answer from the DB, this loop:

specIDs = await findSpecs(fileName, filePath)
        .catch(err => {
            reject(err);
            console.log(fileName + ' not found')
        });
        if (typeof specIDs !== 'undefined' && specIDs) {
            console.log('FOUND!!!!');
            var addLoadSpec = [];
            for (let i = 0; i < specIDs.length; i++) {

Get's error for index of undefined

How do I make it process files one by one?

[Never pass an `async function` as the executor to `new Promise`](https://stackoverflow.com/q/43036229/1048572)! Also don't use `catch()` syntax to ignore errors - rethrow them at least. — Bergi, Jun 23 '20 at 14:27
"*the syncIDs var takes value of another file*" - that's because your `specIDs` are [missing a `var` declaration](https://stackoverflow.com/q/1470488/1048572) and become an implicitly global variable. — Bergi, Jun 23 '20 at 14:31
Yeah @Bergi , the missing var declaration for the syncIDs variable was the cause! Thanks man! — Grzesiek My, Jun 24 '20 at 06:43

node.js async/await function called multiple times (before it ends)

0 Answers0