Synchronous Call : Call 2nd function after 1st function is executed completely - node.js

Question

I recently stating coding in node.js and might be a very simple question.
Trying to write a XML parser/validator to validate xml schema and values against values/ xpath stored in an excel sheet.
Now once the validation function is complete I want to call a printResult function to print final result. However if I try to call the function immediately after the first function .. its printing variables initial values and if called within the first which is iterating though the number of xpaths present in excel sheet and printing result with increments.
var mocha = require('mocha');
var assert = require('chai').assert;
var fs = require('fs');
var parseString = require('xml2js').parseString;
var xpath = require('xpath');
var dom = require('xmldom').DOMParser;
var XLSX = require('xlsx');
var Excel = require("exceljs");
var should = require('chai').should();
var HashMap = require('hashmap');
var colors = require('colors');
require('/xmlValidator/dbConnect.js');
var map = new HashMap();
var elementMap = new HashMap();
var resultValue;
//console.log('hello'.green);
map.set("PASS", 0);
map.set("FAIL", 0);
map.set("INVALID_PATH", 0);
function computeResult(elementPath, result) {
var pass = map.get("PASS");
var fail = map.get("FAIL");
var invalidPath = map.get("INVALID_PATH");
elementMap.set(elementPath, result);
if (result == "PASS") {
pass++;
map.set("PASS", pass);
} else if (result == "FAIL") {
fail++;
map.set("FAIL", fail);
} else {
invalidPath++;
map.set("INVALID_PATH", invalidPath)
}
printResult();
}
function printResult() {
var pass = map.get("PASS");
var fail = map.get("FAIL");
var invalidPath = map.get("INVALID_PATH");
console.log(("PASS Count :" + pass).green);
console.log(("FAIL Count :" + fail).red);
console.log(("Inavlid Path :" + invalidPath).yellow);
elementMap.forEach(function(value, key) {
if (value == "INVALID_PATH")
console.log((key + ":" + value).yellow);
else if (value == "FAIL")
console.log((key + ":" + value).red);
else
console.log(key + ":" + value);
});
}
var workbook = new Excel.Workbook();
workbook.xlsx.readFile('utils/' + process.argv[2])
.then(function() {
var worksheet = workbook.getWorksheet(1);
worksheet.eachRow(function(row, rowNumber) {
//console.log(rowNumber);
var row = worksheet.getRow(rowNumber);
var dataPath1 = row.getCell("A").value;
var dataPath2 = row.getCell("B").value;
var dataPath = dataPath1 + dataPath2;
//console.log(dataPath);
var dataValue = row.getCell("D").value;
var flag = row.getCell("E").value;
//console.log(flag)
//console.log(dataValue);
if (!flag)
validate(dataPath, dataValue, rowNumber);
//else console.log("NOT EXECUTED" + rowNumber)
});
})
function validate(dataPath, dataValue, rowNumber) {
var fail = 0;
fs.readFile('utils/' + process.argv[3], 'utf8', function(err, data) {
if (err) {
console.log("ERROR ERROR ERROR ERROR ");
return console.log(err);
}
var doc = new dom().parseFromString(data);
var subId = String(xpath.select1(dataPath, doc));
if (subId == "undefined") {
/*console.log('undefined caught');
console.log("row number :" + rowNumber);*/
var resultValue = "INVALID_PATH";
computeResult(dataPath, resultValue);
} else {
var subId = xpath.select1(dataPath, doc);
var value = subId.lastChild.data;
/*console.log("row number :" + rowNumber);
console.log("actual value: " + value);
console.log("expected value:" + dataValue );*/
if (dataValue == null) {
assert.notEqual(value, dataValue, "value not found");
resultValue = "PASS";
computeResult(dataPath, resultValue);
} else {
if (value == dataValue)
resultValue = "PASS";
else resultValue = "FAIL";
computeResult(dataPath, resultValue);
}
}
});
}
In the code above i want to call printResult() function after validate function is completely executed (workbook.xlsx.readFile)
Can some one please help me out how to use done () function or make sync call ?

Answer 1

If fs.readFileAsync('utils/' + process.argv[3], 'utf8') can be executed once, then validate() will be completely synchronous and calling printResult() after the verification loop will be trivial.
In the main routine, you can simply aggregate two promises ...
var promise1 = workbook.xlsx.readFile();
var promise2 = fs.readFileAsync(); // requires `fs` to be promisified.
... before embarking on the verification loop.
Promise.all([promise1, promise2]).spread(/* verify here */);
Also a whole bunch of tidying can be considered, in particular :
establishing "PASS", "FAIL" and "INVALID_PATH" as constants to avoid lots of repetitive string creation,
using js plain objects in lieu of hashmap,
building map from elementMap inside the print function.
having validate() return its result and building elementMap in the main routine
Here's the whole thing, about as tight as I can get it. I may have made a few assumptions but hopefully not too many bad ones ...
var mocha = require('mocha');
var assert = require('chai').assert;
var Promise = require("bluebird");
var fs = Promise.promisifyAll(require("fs")); // allow Bluebird to take the pain out of promisification.
var parseString = require('xml2js').parseString;
var xpath = require('xpath');
var dom = require('xmldom').DOMParser;
var XLSX = require('xlsx');
var Excel = require("exceljs");
var should = require('chai').should();
// var HashMap = require('hashmap');
var colors = require('colors');
require('/xmlValidator/dbConnect.js');
const PASS = "PASS";
const FAIL = "FAIL";
const INVALID_PATH = "INVALID_PATH";
function printResult(elementMap) {
var key, result,
map = { PASS: 0, FAIL: 0, INVALID_PATH: 0 },
colorNames = { PASS: 'black', FAIL: 'red', INVALID_PATH: 'yellow' };
for(key in elementMap) {
result = elementMap[key];
map[(result === PASS || result === FAIL) ? result : INVALID_PATH] += 1;
console.log((key + ": " + result)[colorNames[result] || 'black']); // presumably colors can be applied with associative syntax? If so, then the code can be very concise.
}
console.log(("PASS Count: " + map.PASS)[colorNames.PASS]);
console.log(("FAIL Count: " + map.FAIL)[colorNames.FAIL]);
console.log(("Inavlid Path: " + map.INVALID_PATH)[colorNames.INVALID_PATH]);
}
function validate(doc, dataPath, dataValue) {
var subId = xpath.select1(dataPath, doc),
value = subId.lastChild.data,
result;
if (String(subId) == "undefined") {
result = INVALID_PATH;
} else {
if (dataValue === null) {
assert.notEqual(value, dataValue, "value not found"); // not too sure what this does
result = PASS;
} else {
result = (value === dataValue) ? PASS : FAIL;
}
}
return result;
}
//Main routine
var workbook = new Excel.Workbook();
var promise1 = workbook.xlsx.readFile('utils/' + process.argv[2]); // from the question, workbook.xlsx.readFile() appears to return a promise.
var promise2 = fs.readFileAsync('utils/' + process.argv[3], 'utf8');
Promise.all([promise1, promise2]).spread(function(data2, data3) {
var worksheet = workbook.getWorksheet(1),
doc = new dom().parseFromString(data3),
elementMap = {};
worksheet.eachRow(function(row, rowNumber) {
// var row = worksheet.getRow(rowNumber); // row is already a formal variable ???
var dataPath, dataValue;
if (!row.getCell('E').value)
dataPath = row.getCell('A').value + row.getCell('B').value;
dataValue = row.getCell('D').value;
elementMap[dataPath] = validate(doc, dataPath, dataValue);
});
printResult(elementMap);
});
Untested so may not run but at least you can raid the code for ideas.