在mongodb中投影时添加对象

Question

我在数据库中有如下所示的对象

 [ {
        _id:12,
        name:"access",
        mobileNo:9153438340
    },
    {
        _id:13,
        name:"Apple",
        mobileNo:9153438343
    },
    {
        _id:14,
        name:"Dell",
        mobileNo:9153438344
    }]

我想在投影期间添加另一个对象

 {
        _id:15,
        name:"Skype",
        mobileNo:9153438345
    }  

最终结果将是对象应该组合并且结果应该是

[
    {
        _id:12,
        name:"access",
        mobileNo:9153438340
    },
    {
        _id:13,
        name:"Apple",
        mobileNo:9153438343
    },
    {
        _id:14,
        name:"Dell",
        mobileNo:9153438344
    }

   {
    _id:15,
    name:"Skype",
    mobileNo:9153438345
}  
]
enter code here

我尝试了以下查询以获得所需的查询结果

    db.collection.aggregate([
  {
    $project: {
      _id: 1,
      name: 1,
      mobileNo: 1
      // Include other fields from the existing documents as needed
    }
  },
  {
    $project: {
      combinedResults: {
        $concatArrays: [
          [
            {
              _id: 15,
              name: "test",
              mobileNo: 9553438343
              // Add other fields to the new object as needed
            }
          ],
          "$$ROOT" // Include the existing documents
        ]
      }
    }
  },
  {
    $unwind: "$combinedResults" // Unwind the array to get separate documents
  }
]);
enter code here

但是它没有按预期工作，还有其他方法吗？

Answer 1

1. $project

2. $group

   - 使用

   combineResults

   数组将多个文档分组为单个文档。

3. $set

   - 设置

   combineResults

   数组。对于您添加的对象，应该包装在一个数组中。

4. $unwind

   - 解构

   combineResults

   数组。

5. $replaceWith

   - 将输入文档替换为

   combineResults

   对象。

db.collection.aggregate([
  {
    $project: {
      _id: 1,
      name: 1,
      mobileNo: 1// Include other fields from the existing documents as needed
      
    }
  },
  {
    $group: {
      _id: null,
      combinedResults: {
        $push: "$$ROOT"
      }
    }
  },
  {
    $set: {
      combinedResults: {
        $concatArrays: [
          "$combinedResults",
          [
            {
              _id: 15,
              name: "test",
              mobileNo: 9553438343// Add other fields to the new object as needed
              
            }
          ]
        ]
      }
    }
  },
  {
    $unwind: "$combinedResults"// Unwind the array to get separate documents
    
  },
  {
    $replaceWith: "$combinedResults"
  }
])

演示@Mongo Playground