nodejs 连接mongodb

var url, mongoose, options,dataSource;

mongoose = require('mongoose');
mongoose.Promise = global.Promise;
url = 'mongodb://127.0.0.1:27017/test' ;
options = {
    db: {
        native_parser: true
    },
    server: {
        auto_reconnect: true,
        poolSize: 5
    }
};

mongoose.connect(url, options, function (err, res) {
    if (err) {
        console.log('[mongoose log] Error connecting to: ', +url + '. ' + err);
        return process.exit(1);
    } else {
        return console.log('[mongoose log] Successfully connected to: ', +url);
    }
});
dataSource = mongoose.connection;
dataSource.on('error', console.error.bind(console, 'mongoose connection error:'));

dataSource.once('open', function () {
    return console.log('mongoose open success');
});
module.exports = dataSource;