Node.js mongoose.createconnection缺少数据库错误

我试图做的是获取本地主机服务器上的数据库列表，我获取ip地址，在本例中是本地主机和数据库服务器的端口，并调用下面的服务

app.post('/loadDataBase', function(req,res){
    app.set('mongoose').connection.close();
    var mongoose = require('mongoose')
       , Admin = mongoose.mongo.Admin;
// create a connection to the DB
  var connectionStr="mongodb://"+req.body.host+":"+req.body.port;
    /* var connection = mongoose.createConnection(
     'mongodb://127.0.0.1');*/
    var connection = mongoose.createConnection(connectionStr) ;
    connection.on('open', function() {
        // connection established
        new Admin(connection.db).listDatabases(function(err, result) {

            // database list stored in result.databases
            var allDatabases = result.databases;

            res.send(allDatabases);
        });
    });
});'

我在控制台中遇到的错误是缺少数据库名称，因为我必须只连接数据库服务器，我在哪里缺少了一些东西

app.post('/loadDataBase', function(req,res){
    app.set('mongoose').connection.close();
    var mongoose = require('mongoose')
       , Admin = mongoose.mongo.Admin;
// create a connection to the DB
  var connectionStr="mongodb://"+req.body.host+":"+req.body.port;
    /* var connection = mongoose.createConnection(
     'mongodb://127.0.0.1');*/
    var connection = mongoose.createConnection(connectionStr) ;
    connection.on('open', function() {
        // connection established
        new Admin(connection.db).listDatabases(function(err, result) {

            // database list stored in result.databases
            var allDatabases = result.databases;

            res.send(allDatabases);
        });
    });
});'

app.post('/loadDataBase', function(req,res){
    app.set('mongoose').connection.close();
    var mongoose = require('mongoose')
       , Admin = mongoose.mongo.Admin;
// create a connection to the DB
  var connectionStr="mongodb://"+req.body.host+":"+req.body.port;
    /* var connection = mongoose.createConnection(
     'mongodb://127.0.0.1');*/
    var connection = mongoose.createConnection(connectionStr) ;
    connection.on('open', function() {
        // connection established
        new Admin(connection.db).listDatabases(function(err, result) {

            // database list stored in result.databases
            var allDatabases = result.databases;

            res.send(allDatabases);
        });
    });
});'

---

app.set（'mongoose'）.connection.close（）这会关闭我以前的mongoose连接吗
 在端口27017上本地运行mongod时，这对我来说很有效。它成功地打印出数据库列表及其磁盘

app.post('/loadDataBase', function(req,res){
    app.set('mongoose').connection.close();
    var mongoose = require('mongoose')
       , Admin = mongoose.mongo.Admin;
// create a connection to the DB
  var connectionStr="mongodb://"+req.body.host+":"+req.body.port;
    /* var connection = mongoose.createConnection(
     'mongodb://127.0.0.1');*/
    var connection = mongoose.createConnection(connectionStr) ;
    connection.on('open', function() {
        // connection established
        new Admin(connection.db).listDatabases(function(err, result) {

            // database list stored in result.databases
            var allDatabases = result.databases;

            res.send(allDatabases);
        });
    });
});'

var mongoose = require('mongoose')
  , Admin = mongoose.mongo.Admin;

var connection = mongoose.createConnection('mongodb://localhost:27017') ;
connection.on('open', function() {
  // connection established
  new Admin(connection.db).listDatabases(function(err, result) {

    // database list stored in result.databases
    var allDatabases = result.databases;

    console.log(allDatabases);
  });
});

你能给我你的准确错误输出吗？这也许能帮助我诊断出问题所在

app.post('/loadDataBase', function(req,res){
    app.set('mongoose').connection.close();
    var mongoose = require('mongoose')
       , Admin = mongoose.mongo.Admin;
// create a connection to the DB
  var connectionStr="mongodb://"+req.body.host+":"+req.body.port;
    /* var connection = mongoose.createConnection(
     'mongodb://127.0.0.1');*/
    var connection = mongoose.createConnection(connectionStr) ;
    connection.on('open', function() {
        // connection established
        new Admin(connection.db).listDatabases(function(err, result) {

            // database list stored in result.databases
            var allDatabases = result.databases;

            res.send(allDatabases);
        });
    });
});'

关于关闭以前的mongoose连接的问题：您可以使用mongoose.disconnect（）关闭连接。但是，与其反复连接和断开连接，不如在应用程序启动时连接一次，然后在应用程序关闭时断开连接

app.post('/loadDataBase', function(req,res){
    app.set('mongoose').connection.close();
    var mongoose = require('mongoose')
       , Admin = mongoose.mongo.Admin;
// create a connection to the DB
  var connectionStr="mongodb://"+req.body.host+":"+req.body.port;
    /* var connection = mongoose.createConnection(
     'mongodb://127.0.0.1');*/
    var connection = mongoose.createConnection(connectionStr) ;
    connection.on('open', function() {
        // connection established
        new Admin(connection.db).listDatabases(function(err, result) {

            // database list stored in result.databases
            var allDatabases = result.databases;

            res.send(allDatabases);
        });
    });
});'