如何从Mongodb/mongoose中的对象内部存在的数组中删除元素 [英] How to Delete an element from the array which is present inside an object in Mongodb/mongoose

问题描述

以下是对话"集合的文档结构

Here is the struncture of a document of the collection 'conversations'

{
    "_id" : ObjectId("553778c0d3adab10206060db"), //conversation id
    "messages" : [
        {
            "from" : ObjectId("5530af38576214dd3553331c"),
            "_id" : ObjectId("553778c0d3adab10206060dc"),//message id
            "created" : ISODate("2015-04-22T10:32:32.056Z"),
            "read" : false,
            "message" : "second object first msg",
            "participants" : [
                ObjectId("5530af38576214dd3553331c"), //participant id
                ObjectId("553777f2d3adab10206060d8")//participant id
            ]
        },
        {
            "from" : ObjectId("5530af38576214dd3553339b"),
            "_id" : ObjectId("553778c0d3adab10206060dc"),//message id
            "created" : ISODate("2015-04-22T10:32:32.059Z"),
            "read" : false,
            "message" : "second object second msg",
            "participants" : [
                ObjectId("5530af38576214dd3553331c"),//participant id
                ObjectId("553777f2d3adab10206060d8")//participant id
            ]
        }
    ],
    "participants" : [
        ObjectId("5530af38576214dd3553331c"),
        ObjectId("553777f2d3adab10206060d8")
    ],
    "__v" : 0
}

每个文档都包含消息"数组，该数组又包含消息对象作为数组元素.每个对象都有参与者数组.

Each document contains 'messages' array which in turn contains messages objects as array elements. Each object has participants array.

我有对话ID，消息ID，参与者ID.

I am having conversation id , message id , participant id.

我想从参与者"数组(消息"数组的消息对象中存在的参与者"数组)中删除特定元素. 我尝试了这段代码.

I want to delete a particular element from the 'participants' array( the 'participants' array which is present in the message object of the 'messages' array). I tried this code.

var query = { _id: mongoose.Types.ObjectId(req.conversation.id), 'messages._id':req.params.messageId};
Conversation.findOneAndUpdate(query, {$pull: {'participants' : participant_id}}, function(err, data){})

但是它正在从外部参与者"数组中删除对象元素. 请帮助我完成此操作.

But it is deleting the object element from the outer 'participants' array. Please help me to get this done.

谢谢

推荐答案

检查mongo 位置运算符，查询如下:

Check mongo positional operator, query as below :

db.conversations.update({
  "_id": ObjectId("553778c0d3adab10206060db"),
  "messages": {
    "$elemMatch": {
      "_id": ObjectId("553778c0d3adab10206060dc")
    }
  },
  "messages": {
    "$elemMatch": {
      "participants": {
        "$in": [ObjectId("5530af38576214dd3553331c")]
      }
    }
  }
}, {
  "$pull": {
    "messages.$.participants": {
      "$in": [ObjectId("5530af38576214dd3553331c")]
    }
  }
})

这将从匹配的message数组中删除给定的participants对象.希望如此对您有帮助，您应该将其转换为猫鼬.

This remove given participants object from matching message array. And hope so this will help you and you should convert it into mongoose.

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