如何对数据进行分组并获取所有字段并返回mongodb

Question

我在 mongodb 中有集合，想要按修改对发票进行分组并获取这些对象中的所有字段。

{ 
   modified: "11/02/2020",
   stocks: [
             {
              product:{
                 name:"Milk",
                 price: 20
              }
              quantity: 2,
              paid: true
            }
          ]
},
{ 
  modified: "10/02/2020",
  stocks: [
             {
              product:{
                 name:"Sugar",
                 price: 50
              }
              quantity: 1,
              paid: false
            }
   ]
 },
 { 
   modified: "10/02/2020",
   stocks: [
             {
              product:{
                       name:"Butter",
                       price: 10
                    }
              quantity: 5,
              paid: false
            }
        ]
   }

所以我尝试：

  db.collection.aggregate([{
        $group: {
          _id: "$modified",  
          records: { $push: "$$ROOT" } 
        }
     }
  ])

但它在被推入记录的修饰符字段上重新聚合，生成重复项

Answer 1

演示 - https://mongoplayground.net/p/4AGuo5zfF4V

使用$group

db.collection.aggregate([
  {
    $group: { _id: "$grade",  records: { $push: "$$ROOT" } }
  }
])

输出

[
  {
    "_id": "A",
    "records": [
      {
        "_id": ObjectId("5a934e000102030405000000"),
        "grade": "A",
        "name": "John",
        "subject": "English"
      },
      {
        "_id": ObjectId("5a934e000102030405000001"),
        "grade": "A",
        "name": "John1",
        "subject": "English"
      }
    ]
  },
  {
    "_id": "B",
    "records": [
      {
        "_id": ObjectId("5a934e000102030405000002"),
        "grade": "B",
        "name": "JohnB",
        "subject": "English"
      },
      {
        "_id": ObjectId("5a934e000102030405000003"),
        "grade": "B",
        "name": "JohnB1",
        "subject": "English"
      }
    ]
  }
]