TypeError:从mongodb检索html字符串时，将循环结构转换为JSON

Question

我正在将一个html片段保存到mongodb数据库中，保存操作成功，但从mongo检索数据会导致"TypeError:将循环结构转换为JSON"失败。

代码很简单

let database;
let connection;
exports.connectDatabase = function(MONGO_URL,DB_NAME) {
MongoClient.connect(  MONGO_URL,  { useNewUrlParser: true, useUnifiedTopology: true }, (err, client) => {
database = client.db(DB_NAME);
connection = client;
}
);
};
exports.getDatabase = function(){
return database;
};

exports.saveHtml = async function(req, res) {
try{
await getDatabase().collection('htmls').insertOne({name:req.body.title,  html:req.body.content });
res.send('success');
}catch(e){
console.log(e);
res.json(404);
return;
}
}
exports.getSavedHtmls =  async function(req,res){
try{
let html = await getDatabase().collection('htmls').find({});
res.send(html);
}catch(e){
console.log(e);
res.json(404);
return;
}
}

错误是

TypeError: Converting circular structure to JSON
--> starting at object with constructor 'NativeTopology'
|     property 's' -> object with constructor 'Object'
|     property 'sessionPool' -> object with constructor 'ServerSessionPool'
--- property 'topology' closes the circle
at JSON.stringify (<anonymous>)
at stringify (/Users/xisizhe/Documents/server/node_modules/_express@4.17.1@express/lib/response.js:1123:12)

我该如何解决这个问题？

Answer 1

getDatabase().collection('htmls').find({})返回一个FindCursor。

您需要调用toArray来获得一个可以转换为JSON的文档数组。