Question

我在 mongo 文档中有这个数组：

"labels" : [ 
    {
        "id" : "4b19c495-8c40-4c92-8c7d-ae9fb8defd20",
        "labelCategory" : "Content",
        "labelType" : "Content_label",
        "code" : 5,
        "labelName" : "HR Request Forms",
        "trustValue" : 1.0,
        "riskValue" : 0.0,
        "sensitivity" : 0.2,
        "concrete" : 0.8,
        "threshold" : 2.0,
        "abstracts" : [ 
            "707babad-231f-82bb-014c-8506d3dc784e"
        ]
    }, 
    {
        "id" : "707babad-231f-82bb-014c-8506d3dc784e",
        "labelCategory" : "Content",
        "labelType" : "Content_label",
        "code" : 5,
        "labelName" : "HR Information",
        "trustValue" : 1.0,
        "riskValue" : 0.0,
        "sensitivity" : 0.2,
        "concrete" : 0.2,
        "threshold" : 2.0,
        "abstracts" : []
    }, 
    {
        "id" : "9cdce502-1dd9-4ef9-b78b-7f7c638490bf",
        "labelCategory" : "Virtual",
        "labelType" : "Virtual_label",
        "code" : 1,
        "labelName" : "Object Low Sensitive",
        "trustValue" : 1.0,
        "riskValue" : 0.0,
        "sensitivity" : 0.0,
        "concrete" : 0.0,
        "threshold" : 0.0,
        "abstracts" : []
    }
],

现在我只有这个查询：

db.getCollection('objects-89aafe20-780f-46ec-aaa0-a2d95bae542e').find(
{
    objectCategory:"Content",
    "labels":{
    $elemMatch:{"labelCategory" : "Content", labelName:{$ne:"Other"}}
    }
}, 
{objectName:1, _id:0, labels:{labelName:1}}
)

电流输出：

{
    "labels" : [ 
        {
            "labelName" : "HR Request Forms"
        }, 
        {
            "labelName" : "HR Information"
        }, 
        {
            "labelName" : "Object Low Sensitive"
        }
    ],
    "objectName" : "hr-L1-4.xls"
}

我试图仅获取与包含“labelCategory”：“Content”的对象相关的“labelName”（排除称为：“labelCategory”：“Virtual”的对象） . 有什么建议么？谢谢。

Answer 1

$filter 迭代 labels 的循环并匹配两个条件，它将从 labels 数组返回过滤后的文档
$let 声明一个 labels 变量及以上的 $filter 将在标签内，$$labels 中的 in 指的是声明的变量，$$labels.labelName 将返回字符串数组

db.getCollection('objects-89aafe20-780f-46ec-aaa0-a2d95bae542e').find({
  objectCategory: "Content",
  labels: {
    $elemMatch: {
      labelCategory: "Content",
      labelName: { $ne: "Other" }
    }
  }
},
{
  _id: 0,
  objectName: 1,
  labels: {
    $let: {
      vars: {
        labels: {
          $filter: {
            input: "$labels",
            cond: {
              $and: [
                { $eq: ["$$this.labelCategory", "Content"] },
                { $ne: ["$$this.labelName", "Other"] }
              ]
            }
          }
        }
      },
      in: "$$labels.labelName"
    }
  }
})

Playground

mongoDB - 我如何使用投影并用其值排除特定字段？

1 个答案: