node.js MongoDB查询未返回结果 [英] node.js MongoDB query not returning results

问题描述

我正在玩mongodb，并在用户"集合中输入了一些测试数据{name:"david"}.通过输入

I was playing around with mongodb and entered some test data {name:"david"} into the 'users' collection. I verified that the data was in MongoDB using the mongo shell by typing

db.users.find()

结果:

{ "name":"david" }

在node.js脚本中，以下代码:

In node.js script, the following code:

db.open(function(err, db) {
    if (!err) {
        console.log("db opened!");
    }
    else {
        console.log(err);
    }
    db.collection('users', function(err, collection) {
        collection.find({}, function(err, cursor) {
            cursor.each(function(err, item) {
                console.log(item);
            });
        });
    });
    db.close();
});

不返回任何结果

我没有发现任何错误，也没有错误返回.请指教

I don't see anything wrong, and no err returns. Please advise

推荐答案

您实际上是在从集合中返回数据之前关闭数据库连接.

You're actually closing your database connection before data from the collection has returned.

db.collection('users', function(err, collection) {
  collection.find({}, function(err, cursor) {
    cursor.each(function(err, item) {
      console.log(item);
    });

    // our collection has returned, now we can close the database
    db.close();
  });
});

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