go - 将一个字符串连接到一个结构片段

Question

我正在尝试创建一个端点 Go API 以供前端 JavaScript 图形库使用。

应该发生什么:

1. /data 端点以获取 JSON 数据数组。
2. 数据只是一片 go 结构，在这个例子中只有两个，但它将超过 10000。
3. 图形库需要额外的元数据。它被保存为一个名为 AdditionalInfo 的变量。
4. 问题是当我想对 AdditionalInfo + AllAgents 进行编码时，它不允许我将字符串与结构片段连接起来。
5. 在结构 slice 的末尾还需要一个 ]` 使其成为有效的 JSON

问题:

1. 如何在结构 slice 的前后添加额外数据？
2. 将结构附加到结构 slice 是否有效？

3. 创建一个已知长度的 slice 然后使用范围附加到它会更好吗？

   package main
   
   import (
       "encoding/json"
       "fmt"
       "log"
       "net/http"
       "os"
   )
   
   func main() {
       port := os.Getenv("PORT")
       if port == "" {
           port = "443"
           log.Printf("Defaulting to port %s", port)
       }
   
       http.HandleFunc("/data", TrySnipped)
       log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))
   
   }
   
   func TrySnipped(w http.ResponseWriter, r *http.Request) {
       w.Header().Add("Content-Type", "application/json")
       var AllAgents []SingleAgent
       AllAgents = append(AllAgents, FirstAgent)
       AllAgents = append(AllAgents, SecondAgent)
   
       json.NewEncoder(w).Encode(AllAgents)
   
   }
   
   var AdditionalInfo = `"meta": {
               "page": 1,
               "pages": 1,
               "perpage": -1,
               "total": 350,
               "sort": "asc",
               "field": "RecordID"
           },
           "data": [`
   
   type SingleAgent struct {
       RecordID             string `json:"RecordID"`
       OldEmployeeID        string `json:"OldEmployeeID"`
       NewEmployeeID        string `json:"NewEmployeeID"`
       AgentRank            int    `json:"AgentRank"`
       AgentName            string `json:"AgentName"`
       AgentEmail           string `json:"AgentEmail"`
       TeamManager          string `json:"TeamManager"`
       LineOfBusiness       string `json:"LineOfBusiness"`
       FitnessCampStartDate string `json:"FitnessCampStartDate"`
       FitnessCampEndDate   string `json:"FitnessCampEndDate"`
       FitnessCampStatus    int    `json:"FitnessCampStatus"`
       AgentFitnessRank     int    `json:"AgentFitnessRank"`
       LatestMetricA        int    `json:"MetricA"`
       LatestMetricB        int    `json:"MetricB"`
       LatestMetricC        int    `json:"MetricC"`
       LatestMetricD        int    `json:"MetricD"`
       LatestMetricE        int    `json:"MetricD"`
       SiteName             string `json:"SiteName"`
       SiteID               string `json:"SiteID"`
       PostCampWeek1        string `json:"PostCampWeek1"`
       PostCampWeek2        string `json:"PostCampWeek2"`
       PostCampWeek3        string `json:"PostCampWeek3"`
   }
   
   var FirstAgent = SingleAgent{
       RecordID:             "30",
       OldEmployeeID:        "785114544",
       NewEmployeeID:        "10785114544",
       AgentRank:            3,
       AgentName:            "Shandeigh Rawsen",
       AgentEmail:           "shandeigh.rawsen@gmail.com",
       TeamManager:          "Oliver Lamplugh",
       LineOfBusiness:       "BMS",
       FitnessCampStartDate: "8/13/2018",
       FitnessCampEndDate:   "10/7/2018",
       FitnessCampStatus:    1,
       AgentFitnessRank:     1,
       LatestMetricA:        77,
       LatestMetricB:        167,
       LatestMetricC:        496,
       LatestMetricD:        72,
       LatestMetricE:        80,
       SiteName:             "Montreal",
       SiteID:               "4",
       PostCampWeek1:        "10/2/2018",
       PostCampWeek2:        "10/9/2018",
       PostCampWeek3:        "10/19/2018",
   }
   var SecondAgent = SingleAgent{
       RecordID:             "29",
       OldEmployeeID:        "980433290",
       NewEmployeeID:        "10980433290",
       AgentRank:            4,
       AgentName:            "Terrijo Dewberry",
       AgentEmail:           "terrijo.deberry@gmail.com",
       TeamManager:          "Oliver Lamplugh",
       LineOfBusiness:       "BTSW",
       FitnessCampStartDate: "7/28/2018",
       FitnessCampEndDate:   "9/23/2018",
       FitnessCampStatus:    2,
       AgentFitnessRank:     2,
       LatestMetricA:        88,
       LatestMetricB:        92,
       LatestMetricC:        716,
       LatestMetricD:        78,
       LatestMetricE:        66,
       SiteName:             "Montreal",
       SiteID:               "2",
       PostCampWeek1:        "10/2/2018",
       PostCampWeek2:        "10/9/2018",
       PostCampWeek3:        "10/15/2018",
   }
   

Answer 1

将附加信息、代理和右大括号写入响应:

 io.WriteString(w, "{")
 io.WriteString(w, AdditionalInfo)
 json.NewEncoder(w).Encode(AllAgents)
 io.WriteString(w, "]}")  // closing ] for data and closing } for root

请注意，这对代理进行了两级 [ ] 编码。不清楚这是否是您想要的。

另一种方法是创建一个匹配输出结构的 Go 值并对其进行编码:

v := map[string]interface{}{
    "meta": map[string]interface{}{
        "page":    1,
        "pages":   1,
        "perpage": -1,
        "total":   350,
        "sort":    "asc",
        "field":   "RecordID",
    },
    "data": AllAgents,
 }
 if err := json.NewEncoder(w).Encode(v); err != nil {
    // handle error
 }

同样，不清楚您需要在代理周围嵌套多少。您可能需要这种变体:

v := map[string]interface{}{
    "meta": map[string]interface{}{
        "page":    1,
        "pages":   1,
        "perpage": -1,
        "total":   350,
        "sort":    "asc",
        "field":   "RecordID",
    },
    "data": []interface{}{AllAgents},
 }
 if err := json.NewEncoder(w).Encode(v); err != nil {
    // handle error
 }

re: Efficiency 创建最终大小的 slice 通常比使用 append 增量增长 slice 更有效。通过使用指针 slice []*SingleAgent 而不是结构值 slice []SingleAgent 可能会获得一些效率。