整合按键和对象的映射

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我正在尝试从 go 中的两个地图创建对象地图。

第一张地图掌握着钥匙。第二个 map 具有以键作为值的对象。

基本上在这个例子中 - 有规则和这些规则的检测。最后 - 我想要一个以规则名称作为键的地图，以及附加到它们的检测地图（聚合它们）。

最后：我想要这样的东西（取自下面的 typescript 示例）：

[log]: {
  "rule1": [
    {
      "name": "rule1",
      "message": "i found rule1"
    },
    {
      "name": "rule1",
      "message": "i found rule1 again"
    }
  ],
  "rule2": [
    {
      "name": "rule2",
      "message": "i found rule2"
    },
    {
      "name": "rule2",
      "message": "i found rule2 again"
    },
    {
      "name": "rule2",
      "message": "i found rule2 another time"
    }
  ]
}

为了展示这一点，我在 typescript 中创建了这个：

打字稿演示

当我尝试在 go 中做同样的事情时 - 我有点心理障碍，要做到这一点：

去演示

package main

import (
    "fmt"
)

type Rule struct {
    Name string `json:"name"`
}

type Detection struct {
    Name    string `json:"name"`
    Message string `json:"message"`
}

func main() {

    rules := []Rule{
        {
            Name: "rule1",
        },
        {
            Name: "rule2",
        },
    }

    detected := []Detection{
        {
            Name:    "rule1",
            Message: "I found rule1",
        },
        {
            Name:    "rule1",
            Message: "I found rule1 again",
        },
        {
            Name:    "rule2",
            Message: "I found rule2",
        },
        {
            Name:    "rule2",
            Message: "I found rule2 again",
        },
        {
            Name:    "rule2",
            Message: "I found rule2 another time",
        },
    }

    fmt.Println(rules)
    fmt.Println(detected)

    aggregatedDetections := map[string][]Detection{}

    for _, r := range rules {
        fmt.Printf("Assign %s to aggregatedDetections\n", r.Name)
    }

    fmt.Println(aggregatedDetections)

}

我知道，go 老手需要 < 1 分钟来完成此任务；）但是：尽管我认为我对 go 中的地图有基本的了解 - 我不知道这里会发生什么。特别是我如何在地图中分配空数组值，以便在下一步中填充它们。

我的问题终于是：如何获得所需的输出。

正确答案

您可以使用 if _,found := map[element]; 检查地图元素是否存在；找到 {}，如果没有，则使用空切片创建它。然后您可以将元素添加到切片中。

查看代码：

package main

import (
    "fmt"
)

type Rule struct {
    Name string `json:"name"`
}

type Detection struct {
    Name    string `json:"name"`
    Message string `json:"message"`
}

func main() {

    rules := []Rule{
        {
            Name: "rule1",
        },
        {
            Name: "rule2",
        },
    }

    detected := []Detection{
        {
            Name:    "rule1",
            Message: "I found rule1",
        },
        {
            Name:    "rule1",
            Message: "I found rule1 again",
        },
        {
            Name:    "rule2",
            Message: "I found rule2",
        },
        {
            Name:    "rule2",
            Message: "I found rule2 again",
        },
        {
            Name:    "rule2",
            Message: "I found rule2 another time",
        },
    }

    fmt.Println(rules)
    fmt.Println(detected)

    aggregatedDetections := make(map[string][]Detection)

    for _, r := range rules {
        if _, found := aggregatedDetections[r.Name]; !found {
          aggregatedDetections[r.Name] = make([]Detection, 0)
        }
        msg := ""
        switch {
          case len(aggregatedDetections[r.Name]) == 0:
             msg = "I found " + r.Name
          case len(aggregatedDetections[r.Name]) == 1:
             msg = "I found " + r.Name+" again"
        default:             
             msg = "I found " + r.Name+" another time"
        }
        aggregatedDetections[r.Name] = append(aggregatedDetections[r.Name], Detection{
          Name: r.Name,
          Message: msg,
        })
        fmt.Printf("Assign %s to aggregatedDetections\n", r.Name)
    }

    fmt.Println(aggregatedDetections)

}

Playground

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