猫鼬查询或聚合以删除某些子文档字段

Question

说我有以下文件

项目

{
    details: [
            {
                "title": "Name",
                "content": "",
                "is_private": false,
                "order": 0,
                "type": "text"
            },
            {
                "title": "Price",
                "content": "",
                "is_private": true,
                "order": 1,
                "type": "text"
            },
            {
                "title": "Company",
                "content": "",
                "is_private": false,
                "order": 2,
                "type": "text"
            }
        ],
}

如果我只想返回包含details的子文档字段is_private === false，在猫鼬的查询中是否有办法做到这一点，还是我需要使用聚合？

例如

ItemModel
    .find()
    // something should go here to remove

Answer 1

如果您想使用本机聚合查询来做到这一点：

db.getCollection('item').aggregate([
   {
      $unwind:"$details"
   },
   {
      $match:{
         "details.is_private":true
      }
   },
   {
      $group:{
         _id:"$_id",
         details:{
            $push:"$details"
         }
      }
   }
])

输出：

{
    "_id" : ObjectId("5b7d0edb6cfaf771ecf675f0"),
    "details" : [ 
        {
            "title" : "Price",
            "content" : "",
            "is_private" : true,
            "order" : 1.0,
            "type" : "text"
        }
    ]
}