Question

我正在尝试使用mongo-lite从同一个数据库连接访问多个mongo集合。这是一个示例快递应用程序。

var express = require('express')   ;
var app = express();
var http = require('http');
var mongolite = require('mongo-lite');

db = mongolite.connect("mongodb://localhost/fnard", ['col1','col2']);
app.use(express.bodyParser());
app.use(app.router);

app.get('/', function(request, response){
    db.collection('col1').insert({hi:5},function(){});
    db.collection('col2').insert({hi:5},function(){});
    console.log(request.body);      // your JSON
    response.send(request.body);    // echo the result back
});

http.createServer(app).listen(3000, function () {
    console.log('Express server listening on port ' + '3000');
});

以下是我在/上执行GET的错误：

Error: A Server or ReplSetServers instance cannot be shared across multiple Db instances

但是，如果我使用以下代码，GET会按预期插入文档

var express = require('express')   ;
var app = express();
var http = require('http');
var mongolite = require('mongo-lite');

db = mongolite.connect("mongodb://localhost/fnard", ['col1']);
db2 = mongolite.connect("mongodb://localhost/fnard", ['col2']);
app.use(express.bodyParser());
app.use(app.router);

app.get('/', function(request, response){
    db.collection('col1').insert({hi:5},function(){});
    db2.collection('col2').insert({hi:5},function(){});
    console.log(request.body);      // your JSON
    response.send(request.body);    // echo the result back
});

我是否需要为我想要访问的每个集合创建一个新连接？ mongo-lite文档似乎表明情况并非如此 - .connect（）选项允许您指定要使用的集合，但它似乎不起作用。

mongo-lite docs link

Answer 1

竞争条件正在给你错误。以下适用于我：

var express = require('express');
var app = express();
var http = require('http');
var mongolite = require('mongo-lite');

db = mongolite.connect("mongodb://localhost/fnard", ['col1','col2']);
app.use(express.bodyParser());
app.use(app.router);

app.get('/', function(request, response){
    db.collection('col1').insert({hi:5},function(){
        db.collection('col2').insert({hi:5},function(){
            console.log(request.body);      // your JSON
            response.send(request.body);    // echo the result back
        });
    });
});

http.createServer(app).listen(3000, function () {
    console.log('Express server listening on port ' + '3000');
});

您需要嵌套回调。或者，您可以使用async之类的库：

var express = require('express');
var async = require( 'async' );
var app = express();
var http = require('http');
var mongolite = require('mongo-lite');

db = mongolite.connect("mongodb://localhost/fnard", ['col1','col2']);
app.use(express.bodyParser());
app.use(app.router);

app.get('/', function(request, response){
    async.series( [

        // First insert
        function ( callback ) {
            db.collection('col1').insert({hi:5},callback);
        },

        // Second insert
        function ( callback ) {
            db.collection('col2').insert({hi:5},callback);
        }

    // Send response
    ], function ( error, results ) {
        console.log(request.body);      // your JSON
        response.send(request.body);    // echo the result back
    } );
});

http.createServer(app).listen(3000, function () {
    console.log('Express server listening on port ' + '3000');
});

使用Mongo-lite从同一数据库连接访问＆gt; = 2个集合会导致错误

1 个答案: