Question

使用mongodb我试图从其父集合（清单）的子集合（ListingFeatures）中删除属性（_id）。换句话说，我有一个Listing对象，其中包含一个ListingFeature对象列表。 ListingFeature有一个_id属性，我试图删除它。

这是我试过的命令，我认为这可以起作用：

db.Listing.update( { "ListingFeatures._id": { $exists:true } }, { $unset: { "ListingFeatures._id": 1 } }, false, true);

这在完成之前运行了大约30分钟（列表有300万条记录），它没有抛出任何错误或提供任何类型的消息说它成功或不成功，但是Listing.ListingFeatures._id属性仍然存在。

我错过了什么？

这是一个精简的样本列表文档。最后，我想从ListingFeatures集合中删除_id，CreateDate和UpdateDate。

{
  "Address": "1080 DUNLAP ORPHANAGE RD",
  "City": "Unincorporated",
  "ListingFeatures": [
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Status: ACTIVE"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "County: Tipton"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Approximately 10 acre(s)"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "2 total full bath(s)"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "2 total half bath(s)"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "9 total rooms"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "2 stories"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Type:  General Residential"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Master Bedroom is Carpet, Full Bath, Level 1, Walk-In Closet"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Basement is Partial, Unfinished"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Pool features:  Above Ground"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "2 covered parking space(s)"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Yes car garage(s)"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Attached parking"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Cooling features:  220 Wiring, Dual System,Cooling"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Inclusions:  Cooktop, Dishwasher, Gas Cooking, Microwave, Refrigerator, Satellite Dish, Self Cleaning Oven"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Lot features:  Chain Fenced, Landscaped, Level, Some Trees, Wooded"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Lot size is between 10 and 20 acres"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Utilities present:  Public Water, Septic Tank"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Swimming pool(s)"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Basement"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Den"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Laundry room"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Hardwood floors"
    },
    {
      "_id": null,
      "CreateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "UpdateDate": "Sun, 03 Apr 2011 19:40:04 GMT -04:00",
      "Name": "Parking features:  Driveway/Pad, Garage Door Opener(s), Storage Room(s), Workshop(s)"
    }
  ],
  "ZipCode": "38011",
  "_id": {
    "$oid": "4d99055b1b9ba917bcef9443"
  }
}

Answer 1

我很确定你无法删除_id（事实上，你甚至无法删除它上面的索引）。它是MongoDB的保留字段，用作文档标识符。

修改

你去了 - 必须使用$ Position Operator。

> db.stackoverflow.findOne() { "_id" : ObjectId("4db6362c9e631c2a52a7c645"), "Address" : "1080 DUNLAP ORPHANAGE RD", "City" : "Unincorporated", "ListingFeatures" : [ { "someid" : "123", "CreateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "UpdateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "Name" : "Approximately 10 acre(s)" }, { "someid" : "456", "CreateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "UpdateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "Name" : "2 total full bath(s)" } ], "ZipCode" : "38011" }

让我们删除其中someid为“456”的CreateDate。

> db.stackoverflow.update({"ListingFeatures.someid":"456"},{$unset:{"ListingFeatures.$.CreateDate":1}});

现在我们验证CreateDate是否从someid为“456”的元素中消失。

> db.stackoverflow.findOne() { "Address" : "1080 DUNLAP ORPHANAGE RD", "City" : "Unincorporated", "ListingFeatures" : [ { "someid" : "123", "CreateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "UpdateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "Name" : "Approximately 10 acre(s)" }, { "Name" : "2 total full bath(s)", "UpdateDate" : "Sun, 03 Apr 2011 19:40:04 GMT -04:00", "someid" : "456" } ], "ZipCode" : "38011", "_id" : ObjectId("4db6362c9e631c2a52a7c645") }

Answer 2

只有一种方式可以帮助我。甚至与孩子内部的孩子一起工作。

var updated_comment = 0;
db.Document.find().forEach(function(doc){

    function remove_errors(comments){
        comments.forEach(function(comment){
            delete comment.errors
            updated_comment = updated_comment + 1;
            remove_errors(comment.comments);
        });
    }

    remove_errors(doc.comments);

    db.Document.save(doc);
});

print("done updated_comment = " + updated_comment);

从子集合中删除属性

2 个答案: