我在 mlab.com 的 mongodb 中有一个名为“posts”的集合,我正在尝试使用db.collection('posts').find()
. 下面是我创建的 webtask 的代码,我将其命名为mongodb_find
:
var MongoClient = require('mongodb').MongoClient;
var waterfall = require('async').waterfall;
/**
* @param {secret} MONGO_URL - Mongo database url
*/
module.exports = function(ctx, cb) {
var MONGO_URL = ctx.data.MONGO_URL;
if (!MONGO_URL) return cb(new Error('MONGO_URL secret is missing'))
waterfall([
function connect_to_db(done) {
MongoClient.connect(MONGO_URL, function(err, db) {
if(err) return done(err);
done(null, db);
});
},
function find_hits(db, done) {
db
.collection('posts')
.find(
{},
function (err, result) {
if(err) return done( err );
done( null, JSON.stringify(result) );
}
).sort({ hits: -1 }).limit( 2 );
}
], cb);
};
我有一个mongodb_upsert
与此非常相似并且运行良好的 webtask。但是,对于我的mongodb_find
任务,我收到以下错误:
{
"code": 400,
"error": "Error when JSON serializing the result of the JavaScript code.",
"details": "TypeError: Converting circular structure to JSON",
"name": "TypeError",
"message": "Converting circular structure to JSON",
"stack": "TypeError: Converting circular structure to JSON\n at Object.stringify (native)\n at /data/sandbox/lib/sandbox.js:775:48\n at /data/sandbox/node_modules/async/dist/async.js:473:16\n at next (/data/sandbox/node_modules/async/dist/async.js:5315:29)\n at /data/sandbox/node_modules/async/dist/async.js:958:16\n at /data/io/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX/webtask.js:27:6\n at handleCallback (/data/_verquire/mongodb/2.0.48/node_modules/mongodb/lib/utils.js:96:12)\n at Collection.find (/data/_verquire/mongodb/2.0.48/node_modules/mongodb/lib/collection.js:354:44)\n at find_hits (/data/io/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX/webtask.js:23:5)\n at nextTask (/data/sandbox/node_modules/async/dist/async.js:5310:14)"
}
从命令行连接到 mongodb 时,相同的find()
命令可以正常工作:
db.posts.find({}).sort({hits: -1}).limit(2);
集合中的文档设置如下:
{
"_id": {
"$oid": "5a3ff239bda4eaa4ab96ef8b"
},
"title": "Testing 6",
"url": "/jquery/2017/12/22/testing-6.html",
"hits": 2
}
有谁知道这个问题的解决方案?谢谢你。