在mongodb中找不到集合中的數據

Question

我正在嘗試在node.js中練習mongodb。 我已成功連接數據庫，已插入數據庫，但無法從數據庫獲取數據。 這是我的代碼：

var mongo = require("mongodb");
var host = '127.0.0.1';
var port = 1337;
var db = new mongo.Db('nodejs-introduction', new mongo.Server(host, port, {}));

db.open(function(error, dbClient) {
    console.log('We are connected');

});

var collection = db.collection('user');
collection.insert({
    id: "1",
    name: "Musa",
    twitter: "puzzlemusa",
    email: "puzzlemusa@gmail.com"
}, function(error) {
    console.log('Successfully inserted Musa');
});

collection.find({id: "1"}, function(err, cursor) {
    cursor.toArray(function(err, users){
        console.log("Found the following records", users);
    });

});

Answer 1

您遇到了Node.js異步特性的問題。 如果運行此命令，則collection.find可能會在collection.insert之前完成。 試試這個吧。

var mongo = require("mongodb");
var host = '127.0.0.1';
var port = 1337;
var db = new mongo.Db('nodejs-introduction', new mongo.Server(host, port, {}));

db.open(function(error, dbClient) {
    console.log('We are connected');

});

var collection = db.collection('user');
collection.insert({
    id: "1",
    name: "Musa",
    twitter: "puzzlemusa",
    email: "puzzlemusa@gmail.com"
}, function(error) {
    console.log('Successfully inserted Musa');

    collection.find({id: "1"}, function(err, cursor) {
        cursor.toArray(function(err, users){
            console.log("Found the following records", users);
        });
    });
});

通過將查找內容放入插入的回調中，可以確保在插入實際完成之前查找不會運行。

Answer 2

嘗試這個

var mongo = require("mongodb");

var host = '127.0.0.1';
var port = '27017';    // this is my port, change to 1337

var db = new mongo.Db('nodejs-introduction', new mongo.Server(host, port));

db.open(function(err, db) {
  if (err) {
    return console.log(err);
  }

  var collection = db.collection('user');

  insert(collection);

  // find(collection);
});


function insert(collection) {
  collection.insert({
      id: "1",
      name: "Musa",
      twitter: "puzzlemusa",
      email: "puzzlemusa@gmail.com"
  }, function (error) {
      if (error) {
        return console.log(error);
      }

      console.log('Successfully inserted Musa');

      find(collection);
  });
}

function find(collection) {
  collection.find({id: '1'}).toArray(function(err, users) {
    console.log(users);
  });
}