MongoError: le pool d'instances de serveur a été détruit

Question

J'ai construit cette application avec l'aide de cette question je l'ai fait précédemment.

app.js:

var mongolib = require('./middlewares/db.js');
var downloaderCoverageWho = require('./routers/downloaderCoverageWho.js');
var downloaderCoverageIta = require('./routers/downloaderCoverageIta.js');

const start = async function() {
    const conn = await mongolib.connectToMongoDb();
    const coverages = await mongolib.createACollection('coverages');
    const isPageHasUpdates = true; 
    if(isPageHasUpdates) {
        await downloadCoverageIta();
        await downloadCoverageWho();
    }
    await mongolib.closeConnection();
    await console.log('d3.js creation...');
    return 'FINISH';
}
start()
.then(res => console.log(res)) 
.catch(err => console.log(err)); 

async function downloadCoverageWho() {
    await downloaderCoverageWho.download();
    console.log('Finish');
}
async function downloadCoverageIta() {
    await downloaderCoverageIta.download();
    console.log('Finish');
}

db.js:

var fs = require('fs');
var MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/';
const dbName = 'db';
var collCovName = 'coverages';
var collCov;
let myClient;
let myConn;

var methods = {};

methods.getConnection = function() {
    return myConn;
}

methods.connectToMongoDb = async function() {
    return MongoClient.connect(url + dbName)
    .then(function(conn) {
        console.log('Connected to MongoDB');
        myClient = conn;
        myConn = myClient.db(dbName);
        return myConn;
    })
    .catch(function(err) {
        console.log('Error during connection');
        throw err;
    });
}

methods.closeConnection = async function() {
    myClient.close()
    .then(function() {
        console.log('Connection closed');
    })
    .catch(function(err) {
        console.log('Error closing connection');
        throw err;
    });
}

methods.createACollection = async function(collectionName) {
    return myConn.createCollection(collectionName)
    .then(function() {
        console.log('Collection', collectionName, 'created');
    })
    .catch(function(err) {
        console.log('Error during creation of collection', collectionName);
        throw err;
    });
}

methods.insert = async function(collectionName, obj) {
    return myConn.collection(collectionName).updateOne(obj, {$set: obj}, {upsert: true})
    .then(function(res) {
        console.log('Inserted 1 element in', collectionName);
    })
    .catch(function(err) {
        console.log('Error during insertion in', collectionName);
        throw err;
    });
}

module.exports = methods;

downloadCoverageIta.js:

var cheerio = require('cheerio');
var express = require('express');
var fs = require('fs');
var request = require('request');
var textract = require('textract');

var util = require('../helpers/util.js');
var mongolib = require('../middlewares/db.js');

var methods = {};

var outDir = './output/';
var finalFilename = outDir + 'coverage-ita.json'

var urls = [
    {year: '2013', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_0_fileAllegati_itemFile_1_file.pdf'}, 
    {year: '2012', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_5_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2011', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_6_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2010', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_7_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2009', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_8_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2008', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_15_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2007', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_14_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2006', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_13_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2005', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_12_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2004', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_11_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2003', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_10_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2002', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_9_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2001', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_1_fileAllegati_itemFile_0_file.pdf'}, 
    {year: '2000', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_0_fileAllegati_itemFile_0_file.pdf'}
];

var jsons = [];

methods.download = async function(req, res) {
    jsons = await extractText()
    .then(function() {
        console.log('Extract text success');
    })
    .catch(function() {
        console.log('Extract text error');
    });
}; 

async function extractText() {
    var config = {
        preserveLineBreaks: true
    };

    //await extractTextTest();

    await urls.forEach(async function(url) {
        await textract.fromUrl(url.link, config, async function(error, text) {
            if(error) {
                throw error;
            }
            switch(url.year) {
                case '2000': 
                case '2001': 
                case '2002': 
                case '2003':
                case '2004': 
                case '2005': 
                case '2006': 
                case '2007': 
                case '2008': 
                case '2009': 
                case '2010': 
                case '2011': 
                case '2012':
                    await extractTextType1(url, text)
                    .then(function() {
                        console.log('extractTextType1 success');
                    })
                    .catch(function() {
                        console.log('extractTextType1 error');
                    });
                    break;

                case '2013': 
                    extractTextType2(url, text)
                    .then(function() {
                        console.log('extractTextType2 success');
                    })
                    .catch(function() {
                        console.log('extractTextType2 error');
                    });
                    break;

                default:
                    console.log('Error: no case');
            }
        });
    });
}

async function extractTextTest() { // THIS WORKS
    var obj = {A: 'aa', B: 'bb', C: 'cc'};
    await mongolib.insert('coverages', obj);
}

async function extractTextType1(url, text) {
    var matrix = [];
    var map = [];
    var vaccines = [];
    var regionsTemp = [];
    var regions = [];
    var regionLength = [1, 2, 1, 2, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]; 

    // text to matrix
    var textArray = text.split('\n');
    for(var i = 0; i < 23; i++) {
        matrix[i] = textArray[i].split(' ');
    }

    matrix[0].shift();
    vaccines = matrix[0];
    map[0] = vaccines;

    for(var i = 0; i < regionLength.length; i++) {
        var j = i + 1; 
        var indexToRemove = 0;
        var numberToRemove = regionLength[i];
        var region = matrix[j].splice(indexToRemove, numberToRemove);
        regionsTemp.Push(region);
        map[j+1] = matrix[j];
    }

    for(var i = 0; i < regionsTemp.length; i++) {
        var region = '';
        if(regionLength[i] > 1) {
            region = regionsTemp[i].join(' ');
        }
        else {
            region = regionsTemp[i].join('');
        }
        regions.Push(region);
    }
    map[1] = regions;

    vaccines = map.shift(); 
    regions = map.shift(); 

    var thisJson = await map.reduce(function(result, v, i) {
        v.forEach(function(o, k) {
            var obj = util.createJsonObjectCoverage(url.year, 'Italy', vaccines[k], regions[i], o);
            // save on db
            mongolib.insert('coverages', obj); // HERE
            result.Push(obj);
        });
        return result;
    }, jsons);

    util.printOnFile(jsons, finalFilename);
}

function extractTextType2(url, text) {
    var matrix = [];
    var map = [];
    var vaccines = [];
    var regions = [];

    var textArray = text.split('\n');
    for(var i = 0; i < 36; i++) {
        matrix[i] = textArray[i].split(' ');
    }

    vaccines.Push(matrix[0][1].replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, ''));
    for(var i = 1; i < 10; i++) {
        vaccines.Push(matrix[i][0].replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, ''));
    }
    var meningo = ''.concat(matrix[10][0], matrix[11]).replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, '');
    vaccines.Push(meningo);
    var pneumo = ''.concat(matrix[12][0], ' ', matrix[13]).replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, '');
    vaccines.Push(pneumo);
    map[0] = vaccines;

    for(var i = 14; i < matrix.length; i++) { 
        regions.Push(matrix[i][0]);
    }
    map[1] = regions;
    for(var i = 14; i < matrix.length; i++) {
        matrix[i].shift();
        map.Push(matrix[i]);
    }

    vaccines = map.shift(); 
    regions = map.shift(); 

    var thisJson = map.reduce(function(result, v, i) {
        v.forEach(function(o, k) {
            var obj = util.createJsonObjectCoverage(url.year, 'Italy', vaccines[k], regions[i], o);
            // save on db
            mongolib.insert('coverages', obj); // HERE
            result.Push(obj);
        });
        return result;
    }, jsons);

    util.printOnFile(jsons, finalFilename);
}

module.exports = methods;

downloaderCoverageWho.js:

var cheerio = require('cheerio');
var express = require('express');
var fs = require('fs');
var request = require('request');

var util = require('../helpers/util.js');
var mongolib = require('../middlewares/db.js');

var methods = {};
var countries = {
    'Albania': 'ALB',
    'Austria': 'AUT'
};

var outDir = './output/';
var finalData = outDir + 'coverage-eu.json'
var jsons = [];

methods.download = async function(req, res) {
    for(country in countries) {
        var url = 'http://apps.who.int/immunization_monitoring/globalsummary/coverages?c=' + countries[country];
        request(url, (function(country) {
            var thisCountry = country;

            return function(error, res, html) {
                if(error) {
                    throw error;
                }
                $ = cheerio.load(html);
                var years = [];
                var vaccines = [];
                var coverages = [];
                $('.ts .year').each(function() {
                    years.Push($(this).text().trim());
                });
                $('.ts .odd td a, .ts .even td a').each(function() {
                    vaccines.Push($(this).text().trim());
                });
                $('.ts .odd .statistics_small, .ts .even .statistics_small').each(function() {
                    coverages.Push($(this).text().trim());
                });

                const numYears = years.length;
                const numVaccines = vaccines.length;
                for(var vaccineIdx = 0; vaccineIdx < numVaccines; vaccineIdx++) {
                    for(var yearIdx = 0; yearIdx < numYears; yearIdx++) {
                        let obj = {
                            year: years[yearIdx],
                            country: country,
                            region: "",
                            vaccine: vaccines[vaccineIdx],
                            coverage: coverages[vaccineIdx*numYears + yearIdx]
                        }
                        jsons.Push(obj);
                        // save on db
                        mongolib.insert('coverages', obj); // PROBLEM HERE
                    } 
                }
                util.printOnFile(jsons, finalData);
            } 
        })(country)); 
    } 
}; 

module.exports = methods;

Lorsque je lance le code, j'obtiens cette erreur:

(noeud: 11952) UnhandledPromiseRejectionWarning: promesse non gérée rejet (id de rejet: 2950): MongoError: le pool d'instances de serveur était détruit

Je pense qu'il y a le même problème dans les deux fichiers (downloaderCoverageIta et downloaderCoverageWho).

J'ai lu ici que j'appelle probablement db.close() avant que ma inserts soit terminée, mais ce n'est pas vrai. Je ne sais pas comment le réparer. 

C'est la première fois que j'utilise async/await. Comment puis-je résoudre?

Answer 1

J'ai trouvé le problème ... 

J'ai oublié le fait que javaScript est asynchrone :).

Answer 2

Je pense que db.closeConnection() est appelé avant que toutes les réponses aux demandes ne soient traitées, et l'accès à la base de données est terminé.

La cause de ce problème peut être que vous attendez seulement de créer les demandes, mais que vous n'attendez pas leur résultat (réponse).

Vous démarrez la requête avec une instruction comme celle-ci dans une fonction asynchrone:

request(url, (function(country) {
...
})(...));

Cela signifie que la fonction asynchrone attendra l'appel de la fonction request(...), mais pas la fonction de rappel qui gère la réponse.

Vous pouvez également utiliser request(...) de la manière suivante:

const response = await request(url);

Maintenant, votre fonction asynchrone attendra la réponse.