MongoDB奇怪的writeResult行为

Question

我正在使用mongodb(v2.6.7)和mongo(2.6.7)shell客户端.

我试图使用insert和update命令返回的WriteResult对象.

根据mongodocs的错误,它返回一个带有writeError子文档的writeResult对象.但我无法在shell或mongo的javascript文件中访问此子文档.

以下是我的问题的说明.

• 我插入一个对象并获得成功的writeResult.
• 然后我再次使用相同的_id插入,我正在正确设置了"writeError"的屏幕上正确打印了writeResult.
• 当我用printjson()方法打印时,writeResult对象似乎包含writeError
• 但是当我用JSON.stringify()打印它时,我无法看到"writeError".
• writeResult.writeError也是未定义的,因此我无法访问其writeResult.writeError.code属性.

有人可以解释为什么会发生这种情况,以及正确的方法是什么.

afv:PRIMARY>writeResult=db.sysinfo.insert({_id:"myid",otherData:"otherDataValue"})

WriteResult({ "nInserted" : 1 })

afv:PRIMARY>writeResult=db.sysinfo.insert({_id:"myid",otherData:"otherDataValue"})

WriteResult({
    "nInserted" : 0,
    "writeError" : {
        "code" : 11000,
        "errmsg" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: afvadmin.sysinfo.$_id_  dup key: { : \"myid\" }"
    }
})

afv:PRIMARY> printjson(writeResult)
{
    "nInserted" : 0,
    "writeError" : {
        "code" : 11000,
        "errmsg" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: afvadmin.sysinfo.$_id_  dup key: { : \"myid\" }"
    }
}

afv:PRIMARY> JSON.stringify(writeResult);
{"nInserted":0,"nUpserted":0,"nMatched":0,"nModified":0,"nRemoved":0}

afv:PRIMARY> writeResult.writeError

afv:PRIMARY> writeResult.nInserted
0

afv:PRIMARY> writeResult.writeError.code
2015-02-02T16:34:42.402+0530 TypeError: Cannot read property 'code' of undefined

afv:PRIMARY> writeResult["writeError"]

Answer 1

我不知道为什么它以这种方式实现,但是为了访问包含的writeError子文档,你调用getWriteError()一个WriteResult对象:

> writeResult.getWriteError()
WriteError({
  "index": 0,
  "code": 11000,
  "errmsg": "insertDocument :: caused by :: 11000 E11000 duplicate key error index: test.test.$_id_  dup key: { : \"myid\" }",
  "op": {
    "_id": "myid",
    "otherData": "otherDataValue"
  }
})

> writeResult.getWriteError().code
11000

我找不到任何相关的文档.我在打开shell Tab后点击两次writeResult.以查看可用内容,从而弄明白了.