在nedb中更新一行

Question

我在nedb中有以下數據。

["UserId":"1446943507761","UserName":"xxx","link":"xxx.html","taskDone":"false","id":14,"_id":"fdaaTWSxloQZdYlT"] 
["UserId":"1446943507761","UserName":"xxx","link":"xxx.html","taskDone":"false","id":1,"_id":"fzh2cedAXxT76GwB"] 
["UserId":"1446943507761","UserName":"xxx","link":"xxx.html","taskDone":"false","id":0,"_id":"k4loE7XR5gioQk54"] 

我想更新id爲0的行，並將taskDone的值設置爲true。我使用以下查詢將值設置爲true

db.taskmap.update({ _id: "k4loE7XR5gioQk54", UserName:"xxx" }, { $set: { taskDone: "true"} }, function (err, numReplaced) { 
    console.log("replaced---->" + numReplaced); 
    }); 

它更新值，但它更新爲新行。它基本上插入一個具有相同值的新行，除了taskdone值爲true。它不會刪除現有數據。因此，在更新後的最終數據表中，我得到了id 0的兩行，除了taskDone之外，所有值都相同。我不確定我是否做錯了什麼。如果有人能告訴我更新值的正確方法，這將會很有幫助。

Answer 1

update希望四個參數

var Datastore = require('nedb'); 
var db = new Datastore(); 

db.insert(
[ 
    { 
    "UserId":"1446943507761", 
    "UserName":"xxx", 
    "link":"xxx.html", 
    "taskDone":"false", 
    "id":14, 
    "_id":"fdaaTWSxloQZdYlT" 
    }, 
{ 
    "UserId":"1446943507761", 
    "UserName":"xxx", 
    "link":"xxx.html", 
    "taskDone":"false", 
    "id":1, 
    "_id":"fzh2cedAXxT76GwB" 
}, 
{ 
    "UserId":"1446943507761", 
    "UserName":"xxx", 
    "link":"xxx.html", 
    "taskDone":"false", 
    "id":0, 
    "_id":"k4loE7XR5gioQk54" 
    }], 
    function (err, newDocs) { 
    // empty here 
    } 
); 
db.update(
      { _id: "k4loE7XR5gioQk54", UserName:"xxx" }, 
      { $set: { taskDone: "true"} }, 
      {},// this argument was missing 
      function (err, numReplaced) { 
      console.log("replaced---->" + numReplaced); 
      } 
      ); 
// should give the correct result now 
db.find({}).exec(function (err, docs) {console.log(docs);});