I want to push all volume to arrayVolume but can't.
In my opinion the problem is asynchronous. But I search, read document but can't do it run correct.
Please help me solve the code if you can.
That is my gratitude to you.
Many thanks!
function kl(data){
var arrayVolume = [];
for(var key in data){
var dbId = data[key];
viewer.getProperties(dbId, function(e){
var propertiesObj = e.properties;
propertiesObj.forEach(myF);
function myF(obj){
if(obj.displayName === "Volume"){
var volume = obj.displayValue;
arrayVolume.push(volume);
}
}
});
}
alert(arrayVolume);
}
If that viewer.getProperties is an async operation, like an http call, you should use promises.
For example:
async function kl(data) {
var arrayVolume = [];
for (var key in data) {
var dbId = data[key];
await new Promise((resolve, reject) => {
viewer.getProperties(dbId, (e) => {
var propertiesObj = e.properties;
propertiesObj.forEach(myF);
function myF(obj) {
if (obj.displayName === "Volume") {
var volume = obj.displayValue;
arrayVolume.push(volume);
}
}
return resolve();
});
});
}
alert(arrayVolume);
}
Related
I am hoping this is an easy questions, and I just missed something simple. I have a chain of promise returning functions that flow using .then(). My final function takes the data I return, and formats into the correct format, which is then passed back to the client. The issue I am having (I think), is that the server sends the ff variable to the client before the promise from the formatting function is getting resolved. What confuses me, is that when I log the ff variable, it is logging with all the data as expected.
Any thoughts on why this is occurring, what I am doing wrong, and most importantly how to resolve this?
app.get("/subData", function(req, res) {
getConnection().then(function() {
return getSQL();
}).then(function(sql) {
return executeQuery(sql);
}).then(function(data) {
return formatData(data);
}).then(function(ff) {
console.log(ff);
res.status(200).send(ff);
}).catch(function(err) {
console.log("ERR:");
console.log(err);
res.status(405).send(err);
});
});
Here is the final format data function:
function formatData(data) {
var finArr = Array();
return new Promise(function(resolve, reject) {
data.rows.forEach(function(row, fin) {
var tempArr = Array();
row.forEach(function(itm, pos) {
var ttl = data.metaData[pos].name;
var val = itm;
tempArr[ttl] = val;
});
finArr.push(tempArr);
if(fin + 1 == data.rows.length) {
resolve(finArr);
}
});
});
}
It's pretty clear that one of your promises isn't resolving. Why make the resolve() call in your formatData() method conditional? Why not just let the loop run out?
function formatData(data) {
var finArr = Array();
return new Promise(function(resolve, reject) {
data.rows.forEach(function(row, fin) {
var tempArr = Array();
row.forEach(function(itm, pos) {
var ttl = data.metaData[pos].name;
var val = itm;
tempArr[ttl] = val;
});
finArr.push(tempArr);
});
resolve (finArr);
});
}
Indeed, you don't need a Promise here at all, because it's a synchronous operation. And, it's OK to use synchronous operations in .next() chains. Like this.
function formatData(data) {
var finArr = Array();
data.rows.forEach(function(row, fin) {
var tempArr = Array();
row.forEach(function(itm, pos) {
var ttl = data.metaData[pos].name;
var val = itm;
tempArr[ttl] = val;
});
finArr.push(tempArr);
});
return finArr;
}
The issue had nothing to do with promises resolving properly. The issue was in how I was formatting my data to be sent back to the client. I was building an array of associative arrays with the following code. When it was sent to the client, it was being sent as a blank array of arrays.
data.rows.forEach(function(row, fin) {
var tempArr = Array();
row.forEach(function(itm, pos) {
var ttl = data.metaData[pos].name;
var val = itm;
tempArr[ttl] = val;
});
finArr.push(tempArr);
});
return finArr;
What I needed to do was send the data as an array of objects and then convert it to an array of arrays on the client side. By adjusting my code to this, the data properly passed over as I needed.
data.rows.forEach(function(row, fin) {
// Change From var tempArr = Array() to var tempArr = {} to initialize new Object
var tempArr = {};
row.forEach(function(itm, pos) {
var ttl = data.metaData[pos].name;
var val = itm;
tempArr[ttl] = val;
});
finArr.push(tempArr);
});
return finArr;
I am trying to read some data from a file and store it in a database.
This is part of a larger transaction and I need the returned ids for further steps.
async parseHeaders(mysqlCon, ghID, csv) {
var self = this;
var hIDs = [];
var skip = true;
var idx = 0;
console.log("Parsing headers");
return new Promise(async function(resolve, reject) {
try {
var lineReader = require('readline').createInterface({
input: require('fs').createReadStream(csv)
});
await lineReader.on('close', async function () {
console.log("done: ", JSON.stringify(hIDs));
resolve(hIDs);
});
await lineReader.on('line', async function (line) {
line = line.replace(/\"/g, '');
if (line.startsWith("Variable")) { //Variable,Statistics,Category,Control
console.log("found variables");
skip = false; //Ignore all data and skip to the parameter description.
return; //Skip also the header line.
}
if (!skip) {
var data = line.split(",");
if (data.length < 2) { //Variable section done return results.
console.log("Found sub?",line);
return lineReader.close();
}
var v = data[0];
var bidx = data[0].indexOf(" [");
if (bidx > 0)
v = data[0].substring(0, bidx); //[] are disturbing mysql (E.g.; Air temperature [�C])
var c = data[2];
hIDs[idx++] = await self.getParamID(mysqlCon, ghID, v, c, data);//, function(hID,sidx) { //add data in case the parameter is not in DB, yet.
}
});
} catch(e) {
console.log(JSON.stringify(e));
reject("some error occured: " + e);
}
});
}
async getParamID(mysqlCon,ghID,variable,category,data) {
return new Promise(function(resolve, reject) {
var sql = "SELECT ID FROM Parameter WHERE GreenHouseID="+ghID+" AND Variable = '" + variable + "' AND Category='" + category + "'";
mysqlCon.query(sql, function (err, result, fields) {
if(result.length === 0 || err) { //apparently not in DB, yet ... add it (Acronym and Machine need to be set manually).
sql = "INSERT INTO Parameter (GreenHouseID,Variable,Category,Control) VALUES ("+ghID+",'"+variable+"','"+category+"','"+data[3]+"')";
mysqlCon.query(sql, function (err, result) {
if(err) {
console.log(result,err,this.sql);
reject(err);
} else {
console.log("Inserting ",variable," into DB: ",JSON.stringify(result));
resolve(result.insertId); //added, return generated ID.
}
});
} else {
resolve(result[0].ID); //found in DB .. return ID.
}
});
});
}
The functions above are in the base class and called by the following code:
let headerIDs = await self.parseHeaders(mysqlCon, ghID, filePath);
console.log("headers:",JSON.stringify(headerIDs));
The sequence of events is that everything in parseHeaders completes except for the call to self.getParamID and control returns to the calling function which prints an empty array for headerIDs.
The console.log statements in self.getParamID are then printed afterward.
What am I missing?
Thank you
As you want to execute an asynchronous action for every line we could define a handler to do right that:
const once = (target, evt) => new Promise(res => target.on(evt, res));
function mapLines(reader, action) {
const results = [];
let index = 0;
reader.on("line", line => results.push(action(line, index++)));
return once(reader, "close").then(() => Promise.all(results));
}
So now you can solve that easily:
let skip = false;
const hIDs = [];
await mapLines(lineReader, async function (line, idx) {
line = line.replace(/\"/g, '');
if (line.startsWith("Variable")) { //Variable,Statistics,Category,Control
console.log("found variables");
skip = false; //Ignore all data and skip to the parameter description.
return; //Skip also the header line.
}
if (!skip) {
var data = line.split(",");
if (data.length < 2) { //Variable section done return results.
console.log("Found sub?",line);
return lineReader.close();
}
var v = data[0];
var bidx = data[0].indexOf(" [");
if (bidx > 0)
v = data[0].substring(0, bidx); //[] are disturbing mysql (E.g.; Air temperature [�C])
var c = data[2];
hIDs[idx] = await self.getParamID(mysqlCon, ghID, v, c, data);
}
});
Alright, here's what the plan is. Go through each file, add the file into the array. Once all files are added, then combine them using the JSZipUtility and Docxtemplater:
'click .merge-icon': (e) => {
var programId = Router.current().url.split('/').pop();
var programObj = Programs.findOne(programId);
var insertedDocuments = [];
var i = 0;
var count = programObj.activityIds.count;
var fileDownloadPromise = new Promise((resolve, reject) => {
programObj.activityIds.forEach(function(activityId) {
var activityObj = Activities.findOne(activityId);
var documentObj = ActivityFiles.findOne(activityObj.documents.pop()._id);
JSZipUtils.getBinaryContent(documentObj.url(), callback);
function callback(error, content) {
var zip = new JSZip(content);
var doc = new Docxtemplater().loadZip(zip);
var xml = zip.files[doc.fileTypeConfig.textPath].asText();
xml = xml.substring(xml.indexOf("<w:body>") + 8);
xml = xml.substring(0, xml.indexOf("</w:body>"));
xml = xml.substring(0, xml.indexOf("<w:sectPr"));
insertedDocuments.push(xml);
i++;
if (i == count - 1) {
resolve();
}
}
});
});
fileDownloadPromise.then(() => {
JSZipUtils.getBinaryContent('/assets/template.docx', callback);
function callback(error, content) {
console.log(content);
var zip = new JSZip(content);
var doc = new Docxtemplater().loadZip(zip);
setData(doc);
}
function setData(doc) {
doc.setData({
body: insertedDocuments.join('<w:br/><w:br/>')
});
doc.render();
useResult(doc);
}
function useResult(doc) {
var out = doc.getZip().generate({
type: 'blob',
mimeType: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
});
saveAs(out, programObj.name + '.docx');
}
});
}
Turns out nothing's happening. What's wrong with the execution of this Promise here ?
I'm only calling resolve when every file has been loaded in the array.
having fun with promises in JS and trying to craft simple xpath website parser, but I am struggling with logic on finishing overall parsing process, my code is:
var request = require('request');
var xpath = require('xpath');
var dom = require('xmldom').DOMParser;
var olxMain = 'https://www.some.site/';
var xpathRoot = '//a[contains(#href, "https://www.some.site/mask/")]';
var linksXpath = '//a';
var allGlobalLinks = [];
var getLink = function (node) {
for (key in node['attributes']) {
if (node['attributes'][key]['name'] === 'href') {
return node['attributes'][key]['value'];
}
}
}
var getData = function (url, xpathPattern) {
return new Promise(function (resolve, reject) {
console.log("Opening " + url);
var processResponse = function (error, response, body) {
var doc = new dom().parseFromString(body);
var childNodes = xpath.select(xpathPattern, doc);
var links = childNodes.map(function (n) {
return getLink(n);
});
resolve(links);
};
request({url: url}, processResponse);
}
);
}
var arrayUnique = function (x, i, a) {
return a.indexOf(x) == i;
};
var main = function () {
getData(olxMain, xpathRoot).then(function (links) {
links = links.filter(arrayUnique);
var maxThreads = 10, n = 0;
var chunks = [];
for (k in links) {
var url = links[k];
n++;
if (n <= maxThreads)
chunks.push(url);
else {
n = 0;
// console.log(chunks);
Promise.all(chunks.map(function (url) {
return getData(url, linksXpath);
})).then(function (links) {
// add these links to global scope list here
});
console.log("Finished mappings iteration");
});
chunks = [];
}
}
;
});
}
main();
So what I want is basically some kind of threadPool with promises, how to I manage these 10 promises, when they all are finished, I should spawn another 10 more, until list is finished and all Promises have finished ?
I am building a Windows 8 Store app with HTML/CSS/JavaScript. I am reading in data from a text file through a function, and then putting that data into an array. I am trying to return the array through the function, but it is not working. Any help would be greatly appreciated. I've attached my code snippet.
// Load user data
var DefineUserData = function LoadUserData() {
return Windows.Storage.ApplicationData.current.localFolder.getFileAsync(loadfile).done(function (UserFile) {
return Windows.Storage.FileIO.readTextAsync(UserFile).done(function (fileResult) {
var userdata = new Object();
var dataobject = {};
var innercount;
var outercount;
var fileResultByLines = fileResult.split("\n");
for (outercount = 0; outercount <= (fileResultByLines.length - 2) ; outercount++) {
var tempArray = fileResultByLines[outercount].split(",");
dataobject.metrictitle = tempArray[0];
dataobject.numinputs = tempArray[1];
dataobject.inputs = new Array();
for (innercount = 0; innercount <= parseInt(dataobject.numinputs) ; innercount++) {
dataobject.inputs[innercount] = tempArray[innercount + 2];
}
userdata[outercount] = dataobject;
}
return userdata;
});
},
function (errorResult) {
document.getElementById("resbutton1").innerText = errorResult;
})
}
Your DefineUserData function is returning a Promise, not a value. Additionally done functions don't return anything. Instead you'll need to use then functions instead of done functions in DefineUserData and then handle add a done function (or then) to the code that calls this function.
Also, You can make your promises easier to read, and easier to work with by chaining then functions instead of nesting them.
Currently on Win7 at the office so I can't test this, but try something similar to this pseudo-code. Note then functions instead of done. The last then returns your data. Sample snippet afterwards to illustrate calling this and handling the result.
// modified version of yours
var DefineUserData = function LoadUserData() {
return Windows.Storage.ApplicationData.current.localFolder
.getFileAsync(loadfile)
.then(function (UserFile) {
return Windows.Storage.FileIO.readTextAsync(UserFile);
}).then(function (fileResult) {
var userdata = new Object();
var dataobject = {};
var innercount;
var outercount;
var fileResultByLines = fileResult.split("\n");
for (outercount = 0; outercount <= (fileResultByLines.length - 2) ; outercount++) {
var tempArray = fileResultByLines[outercount].split(",");
dataobject.metrictitle = tempArray[0];
dataobject.numinputs = tempArray[1];
dataobject.inputs = new Array();
for (innercount = 0; innercount <= parseInt(dataobject.numinputs) ; innercount++) {
dataobject.inputs[innercount] = tempArray[innercount + 2];
}
userdata[outercount] = dataobject;
}
return userdata;
},
function (errorResult) {
document.getElementById("resbutton1").innerText = errorResult;
});
}
// some other code...
DefineUserData.done(function (userdata) {
// do something
});