mongodb-根据条件字段合并两个对象

如何解决mongodb-根据条件字段合并两个对象

假设我们有以下来自聚合管道的文档：

[
  {
    "_id": ObjectId("5a934e000102030405000000"),"description": "description for item 1","item_code": "00001"
  },{
    "_id": ObjectId("5a934e000102030405000001"),"description": "description for item 2","item_code": "00002"
  },{
    "_id": ObjectId("5a934e000102030405000002"),"description": "description for item 3","item_code": "00003"
  },{
    "_id": ObjectId("5a934e000102030405000003"),"extrafield": "extra field for item 2","item_code": "00002"
  }
]

如何将具有相同item_code的文档合并为一个文档，同时保留所有属性？所需结果：

[
  {
    "description": "description for item 1",{
    "description": "description for item 2",{
    "description": "description for item 3","item_code": "00003"
  }
]

我尝试了不同的$group模式，但没有成功：（

Here's mongodb playground

解决方法

您可以尝试

$group by item_code，将$mergeObjects与$$ROOT合并对象
$replaceWith将根对象替换为根

db.collection.aggregate([
  {
    $group: {
      _id: "$item_code",root: { $mergeObjects: "$$ROOT" }
    }
  },{ $replaceWith: "$root" }
])

Playground