I'm trying to create a new record in my MongoDB ("thisPlayer") and save it to my database, then find all records in my database (including the new one) and render them.
I am having trouble understanding why my save() function actually occurs after my find() function. When this code executes, the find() function does not include my new thisPlayer record. However, after the find() runs, the save occurs -- the record is saved to the database AFTER the find() ran.
Thanks in advance!
const playerNumber = async function countPlayers() {
return new Promise((resolve, reject) => {
Player.count(function(err, numOfDocs) {
err ? reject(err) : resolve(numOfDocs);
console.log('I have '+numOfDocs+' documents in my collection');
});
});
}
async function playerProfile() {
var count = await playerNumber();
console.log("count already in db: "+ count);
if (count===0) {
teamCaptain=1;
} else {teamCaptain=0};
count++;
const thisPlayer = new Player({
playerNum: count,
playerName: Name,
});
thisPlayer.save();
Player.find({}, function(err, playaz){
var playerOne;
if (playaz.length > 0) {
playerOne = playaz[0].playerName;
} else {
playerOne = "";
}
res.renderPjax("leavetakings",
{player1: "1: " + playerOne}
);
});
}
playerProfile();
You need to use await
for example.
await Player.find({})
Related
I am having hard times trying to write data received from a api to db.
I successfully got data and then have to write it to db. The point is to check whether the quote is already exists in my collection.
The problem I am dealing with is that every value gets inserted in my collection, not regarding if it exists or not.
const { MongoClient } = require('mongodb')
const mongoUrl = 'mongodb://localhost/kanye_quotes'
async function connectToDb() {
const client = new MongoClient(mongoUrl, { useNewUrlParser: true })
await client.connect()
db = client.db()
}
async function addQuote(data) {
await connectToDb()
try {
const collection = db.collection('quotes')
let quotes = [];
quotes = await collection.find({}).toArray()
if (quotes = []) { // I added this piece of code because if not check for [], no values will be inserted
collection.insertOne(data, (err, result) => {
if (err) {
return
}
console.log(result.insertedId);
return
})
}
quotes.forEach(quote => {
if (quote.quote !== data.quote) { // I compare received data with data in collection, it actually works fine(the comparison works as it supposed to)
collection.insertOne(data, (err, result) => {
if (err) {
return
}
console.log(result.insertedId);
})
} else console.log('repeated value found'); // repeated value gets inserted. Why?
})
}
catch (err) {
console.log(err)
}
}
Hi it's probably better to set unique: true indexing on your schema. That way you won't have duplicated values.
I did follow How to use MongoDB with promises in Node.js?. The answer 4 by(https://stackoverflow.com/users/5371505/pirateapp), works well with regular mongodb server. But it will not work always with a mongoDB replication set.
const mongodb = require('mongodb');
const MongoClient = mongodb.MongoClient;
// the url talking to replicaSet does not work, while the url with regular mongoDB sever seems working for me.
// const url = 'mongodb://alexlai:alex1765#arch16GMongo01.yushei.me:27017,arch16GMongo02.yushei.me:27017,arch16GMongo03:27017/YuShei?replicaSet=odroid00&connectTimeoutMS=300000';
url = 'mongodb://172.16.1.108/YuShei';
let db = {
open : open,
}
function open(){
return new Promise((resolve, reject)=>{
MongoClient.connect(url, (err, db) => {
if (err) {
reject(err);
} else {
resolve(db);
}
});
});
}
function close(db){
if(db){
db.close();
}
}
// module.exports = db;
// const db = require('./mongoDBServer.js');
const assert = require('assert');
const collectionName= 'yuTsaiLpr20161021'; // a collection contains 500 docs.
// this will hold the final array taht will be sent to browser
// a global variable will be declared with upper camel
let Array = [];
// this will hold database object for latter use
let Database = '';
// global query string and projection
let Query = {};
let Projection = {};
let Collection ={};
let checkoutCarPromise = new Promise((resolve, reject)=>{
Database = null;
db.open() // no ';' semi-column this is a promise, when successful open will be reolved and return with db object, or reject
.then((db)=>{
Database = db; // save it globally
return db.collection(collectionName);
})
.then((collection)=>{
if(collection == 'undefined') reject('collection not found!!');
Collection = collection; //seave it globally
return(collection);
})
.then((collection)=>{
return collection.find(); // return a cursor
})
.then((cursor)=>{
return cursor.toArray();
})
.then((array)=>{
console.log('array[499]: ', array[499]);
Array.push(array[499]);
})
.then(()=>{ // reread to find this car
return Collection.find({plateText:{$regex: /8920/}});
})
.then((cursor)=>{
return cursor.toArray();
})
.then((array)=>{
Array.push(array);
resolve(Array);
})
})
.catch((err)=>{
return(err);
console.error('the checkoutCarPromiserror is: ', err);
})
Promise.all([checkoutCarPromise]).then(results => {
console.log('checkoutCarPromise last resolve value: ', results[0]);
console.log('Array: ', Array);
Database.close();
})
// this will get you more infos about unhandled process
process.on("unhandledRejection", (reason) => {
console.log(reason)
})
I have a large aggrogate query that required me to pass "allowDiskUse: true" as an option. This would not work with the aggegate as described here:
https://github.com/meteorhacks/meteor-aggregate/issues/11
My meteor method is defined here. When I call the method I need to wait for ondata to complete before anything is returned to the client, but nothing I try allows me to get that data in a safe way up to the front end.
Meteor.methods({
'getSummary': function (dept,startDate,endDate,filterType) {
f = myQuery(startdate,enddate,dayFinalGroup);
f.on("data", Meteor.bindEnvironment(function(row) {
//load an array or something here to return
}));
f.once("end", Meteor.bindEnvironment(function() {
// tidy up, in my case end the stream
}));
//here I'd return the array loaded
},
});
This is my front end.
Meteor.call(
'getSummary',0,Session.get('start_date'),Session.get('end_date'),1,
function(error, result){
if(error){
console.log(error);
} else {
Session.set('sumTotals',result);
}
}
);
Finally Got it. I utilized wrapSync
'getSummary': function (dept,startDate,endDate,filterType) {
console.log(dept);
console.log(startDate);
console.log(endDate);
console.log(filterType);
var startdate = new Date(startDate);
var enddate = new Date(endDate);
var arr = [];
f = myQuery(startdate,enddate,dayFinalGroup);
var fetchCursor = Meteor.wrapAsync(function fetchCursor (cursor, cb) {
cursor.each(function (err, doc) {
if (err) return cb(err);
if (!doc) return cb(null, { done: true }); // no more documents
arr.push(doc);
});
});
var myData = fetchCursor(f);
return arr;
From homework 2_2 of the M101JS course at university.mongodb.com.
Write a program that finds the document with the highest recorded temperature for each state, and adds a "month_high" field for that document, setting its value to true.
The following code should work to update the correct doc in the collection adding "month_high". And the problem is here:
//db.collection('data').update(query, setMonthHigh, function(err, updated) {//OK
db.collection('data').update(query, doc, function(err, updated) {// NOT OK, dunno why
The 2nd update line does not save anything. But if I use the commented update above, it works.
Does anyone have an idea why the 2nd update line isn't working (the one that replaces the whole doc)?
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://localhost:27017/weather', function(err, db) {
if(err) throw err;
var options = { 'sort' : [ ['State', 1], ['Temperature', -1] ]};
var lastDoc = null;
var setMonthHigh = {'$set':{'month_high':true}};
var cur = db.collection('data').find({}, {},options);
//var cur = db.collection('data').find({'month_high':true}, {},options);
cur.each(function(err, doc) {
if(err) throw err;
if(doc == null) {
console.log("Document done");
//return db.close();
db.close();
process.exit(0);
}
var query = {'_id' : doc._id};
//db.collection('data').update({'month_high':true}, {$unset:{'month_high':1}}, function(err, updated) {});
//console.dir(doc);
if ( ( lastDoc != null && lastDoc.State != doc.State ) ||
lastDoc == null )
{
doc['month_high'] = 'true';
//db.collection('data').update(query, setMonthHigh, function(err, updated) {//OK
db.collection('data').update(query, doc, function(err, updated) {
// NOT OK, dunno why
if(err) throw err;
console.dir("Update "+updated);
});
console.dir(doc);
}
lastDoc = doc;
});
});
Also, I'm told that using process.exit(0) is a bad hack, but it was the only way I could exit the code without throwing exceptions on return db.close();. If anyone knows a way to exit the code gracefully, that would be great too.
First of all, you have made a mistake in part of your code responsible for updating a database.
db.collection('data').update is an asynchronous function. It means that you cannot execute db.close() without knowing if all updates have been completed. For more details please read: How can I use a cursor.forEach() in MongoDB using Node.js?
Both updates works. However there is one difference between two of them:
db.collection('data').update(query, setMonthHigh, function(err, updated)
updates records with a new field: 'month_high': true <- boolean value
Query to find these records is: db.data.find({'month_high': true})
db.collection('data').update(query, doc, function(err, updated)
updates records with a new field: 'month_high': 'true' <- string value
Query to find these records is: db.data.find({'month_high': 'true'})
Your updated code:
Before run it, first install async library (npm install async)
var async = require('async');
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://localhost:27017/weather', function(err, db) {
if(err) throw err;
var q = async.queue(function (doc, callback) {
db.collection('data').update({_id: doc._id}, doc, callback);
}, Infinity);
var options = { 'sort' : [ ['State', 1], ['Temperature', -1] ]};
var lastDoc = null;
var cur = db.collection('data').find({}, {},options);
cur.each(function(err, doc) {
if(err) throw err;
if(doc === null) return;
if ( ( lastDoc !== null && lastDoc.State !== doc.State ) ||
lastDoc === null )
{
doc['month_high'] = true;
q.push(doc, function(err, updated) {
if(err) throw err;
console.log("Update "+updated);
});
}
lastDoc = doc;
});
q.drain = function() {
if (cur.isClosed()) {
console.log('Document done');
db.close();
}
}
});
I've got a node.js script that loads an XML file. It loops through each element in the Mongo array and says that they're all getting inserted correctly, but when the script has completed a check of db.collection.count(); tells me that far fewer records have been inserted into the database than the number expected.
How can I make mongo and node.js play nicely with inserts?
GrabRss = function() {
var http = require('http');
var sys = require('sys');
var xml2js = require('xml2js');
var fs = require('fs');
var Db = require('../lib/mongodb').Db,
Conn = require('../lib/mongodb').Connection,
Server = require('../lib/mongodb').Server,
// BSON = require('../lib/mongodb').BSONPure;
BSON = require('../lib/mongodb').BSONNative;
var data;
var checked = 0;
var len = 0;
GotResponse = function(res) {
var ResponseBody = "";
res.on('data', DoChunk);
res.on('end', EndResponse);
function DoChunk(chunk){
ResponseBody += chunk;
}
function EndResponse() {
//console.log(ResponseBody);
var parser = new xml2js.Parser();
parser.addListener('end', GotRSSObject);
parser.parseString(ResponseBody);
}
}
GotError = function(e) {
console.log("Got error: " + e.message);
}
GotRSSObject = function(r){
items = r.item;
//console.log(sys.inspect(r));
var db = new Db('myrssdb', new Server('localhost', 27017, {}), {native_parser:false});
db.open(function(err, db){
db.collection('items', function(err, col) {
len = movies.length;
for (i in items) {
SaveItem(items[i], col);
}
});
});
}
SaveItem = function(m, c) {
/* REPLACE FROM HERE IN ANSWER */
c.find({'id': m.id}, function(err, cursor){
cursor.nextObject(function(err, doc) {
if (doc == null) {
c.insert(m, function(err, docs) {
docs.forEach(function(doc) {
console.log('Saved: '+doc.id+' '+doc.keywords);
});
});
} else {
console.log('Skipped: '+m.id);
}
if (++checked >= len) {
process.exit(0);
}
});
});
/* REPLACE TO HERE IN ANSWER */
}
//http.get(options, GotResponse).on('error', GotError);
var x2js = new xml2js.Parser();
fs.readFile('/home/ubuntu/myrss.rss', function(err, data) {
x2js.parseString(data);
});
x2js.addListener('end', GotRSSObject);
}
GrabRss();
As requested, the code is above. The file is read locally (though is used to be an HTTP request, but it's a 25 meg file now, lots of RSS records)
I just ran the file with some ~10k records in it and a count of the items in the mongoDB after the script has run is about 800 items.
As per the answer I replaced the insert code:
with:
c.update({'id': m.id}, {$set: m}, {upsert: true, safe: true}, function(err){
if (err) console.warn(err.message);
else console.log(m.keywords);
if (++checked >= len) {
console.log(len);
//process.exit(0);
process.exit(0);
}
});
By default, MongoDB writes do not check for an error.
You need to set safe:true in the options to your insert, as explained in the documentation for node-mongodb-native:
var collection = new mongodb.Collection(client, 'test_collection');
collection.insert({hello: 'world'}, {safe:true},
function(err, objects) {
if (err) console.warn(err.message);
if (err && err.message.indexOf('E11000 ') !== -1) {
// this _id was already inserted in the database
}
});
Otherwise your callback will not be invoked for errors and your client won't know about them.
You probably also want to look at upserts and updates, as it is incredibly inefficient to do find & insert if null in a loop.
Instead, upsert will update if the matching document exists, otherwise it will insert a new one. An explanation on how to do this in Node is in the documentaiton for the driver.