json - 在服务器上加载 CSV 数据，将数据转换为 JSON 并使用 Golang 使用 Json 查询获取结果

Question

我正在尝试构建一个 TCP 服务器，它从CSV文件加载数据集并提供一个接口来查询数据集。TCP 服务器将暴露 4040 端口。 CSV 文件包含与冠状病毒病例相关的以下列：

• 累积测试阳性
• 进行的累积测试
• 日期
• 出院
• 已到期
• 录取
• 区域用户应该能够在基于 Linux/Unix 的系统上使用NetCat命令连接到服务器。 nc localhost 4040

一旦连接到 TCP，用户应该能够通过发送 JSON 格式的查询与应用程序进行通信。

{
    "query": {
        "region": "Sindh"
    }
}

{
    "query": {
        "date": "2020-03-20"
    }
}

我的服务器.go

package main

import (
    "fmt"
    "net"
    "os"
    "flag"
    "log"
    "encoding/csv"
    "encoding/json"
    "bufio"
    "io"
    "strings"
)

type CovidPatient struct {
    Positive    string      `json:"Covid_Positive"`
    Performed   string      `json:"Coivd_Performed"`
    Date        string      `json:"Covid_Date"`
    Discharged  string      `json:"Covid_Discharged"`
    Expired     string      `json:"Covid_Expired"`
    Region      string      `json:"Covid_Region"`
    Admitted    string      `json:"Covid_Admitted"`
}

type DataRequest struct {   
    Get string `json:"get"`
}

type DataError struct {     
    Error string `json:"Covid_error"`
}

func Load(path string) []CovidPatient {
    table := make([]CovidPatient, 0)
    var patient CovidPatient
    file, err := os.Open(path)
    if err != nil {
        panic(err.Error())
    }
    defer file.Close()

    reader := csv.NewReader(file)
    csvData, err := reader.ReadAll()
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    for _, row := range csvData{
        patient.Positive =  row[0]
        patient.Performed =  row[1]
        patient.Date =       row[2]
        patient.Discharged = row[3]
        patient.Expired =    row[4]
        patient.Region =     row[5]
        patient.Admitted =   row[6]
        table = append(table, patient)
    }
    return table
}

func Find(table []CovidPatient, filter string) []CovidPatient {
    if filter == "" || filter == "*" {
        return table
    }
    result := make([]CovidPatient, 0)
    filter = strings.ToUpper(filter)
    for _, cp := range table {
        if cp.Date == filter ||
            cp.Region == filter ||
            strings.Contains(strings.ToUpper(cp.Positive), filter)      ||
            strings.Contains(strings.ToUpper(cp.Performed), filter)     ||
            strings.Contains(strings.ToUpper(cp.Date), filter)          ||
            strings.Contains(strings.ToUpper(cp.Discharged), filter)    ||
            strings.Contains(strings.ToUpper(cp.Expired), filter)       ||
            strings.Contains(strings.ToUpper(cp.Region), filter)        ||
            strings.Contains(strings.ToUpper(cp.Admitted), filter){
            result = append(result, cp)
        }
    }
    return result
}

var (
    patientsDetail = Load("./covid_final_data.csv")
)

func main(){
    var addr string
    var network string
    flag.StringVar(&addr, "e", ":4040", "service endpoint [ip addr or socket path]")
    flag.StringVar(&network, "n", "tcp", "network protocol [tcp,unix]")
    flag.Parse()

    switch network {
    case "tcp", "tcp4", "tcp6", "unix":
    default:
        fmt.Println("unsupported network protocol")
        os.Exit(1)
    }

    ln, err := net.Listen(network, addr)
    if err != nil {
        log.Println(err)
        os.Exit(1)
    }
    defer ln.Close()
    log.Println("Covid19 Condition in Pakistan")
    log.Printf("Service started: (%s) %s\n", network, addr)
    
    for {
        conn, err := ln.Accept()
        if err != nil {
            log.Println(err)
            conn.Close()
            continue
        }
        log.Println("Connected to ", conn.RemoteAddr())
        go handleConnection(conn)
    }
}
func handleConnection(conn net.Conn) {
    defer func() {
        if err := conn.Close(); err != nil {
            log.Println("error closing connection:", err)
        }
    }()

    reader := bufio.NewReaderSize(conn, 4)

    for {
        buf, err := reader.ReadSlice('}')
        if err != nil {
            if err != io.EOF {
                log.Println("connection read error:", err)
                return
            }
        }
        reader.Reset(conn)
        
        var req DataRequest
        if err := json.Unmarshal(buf, &req); err != nil {
            log.Println("failed to unmarshal request:", err)
            cerr, jerr := json.Marshal(DataError{Error: err.Error()})
            if jerr != nil {
                log.Println("failed to marshal DataError:", jerr)
                continue
            }
            if _, werr := conn.Write(cerr); werr != nil {
                log.Println("failed to write to DataError:", werr)
                return
            }
            continue
        }

        result := Find(patientsDetail, req.Get)

        rsp, err := json.Marshal(&result)
        if err != nil {
            log.Println("failed to marshal data:", err)
            if _, err := fmt.Fprintf(conn, `{"data_error":"internal error"}`); err != nil {
                log.Printf("failed to write to client: %v", err)
                return
            }
            continue
        }
        if _, err := conn.Write(rsp); err != nil {
            log.Println("failed to write response:", err)
            return
        }
    }
}

这会正确加载 csv 并将其转换为 JSON。但是，当我尝试使用 NetCat 命令运行查询时，它返回空 JSON 元素。请指导我哪里出错了。

标签： jsoncsvgotcptcpserver

Answer 1

猜你想要这个：

╭─root@DESKTOP-OCDRD7Q ~
╰─# nc localhost 4040
{"get": "Sindh"}
[{"Covid_Positive":"1","Coivd_Performed":"1","Covid_Date":"1","Covid_Discharged":"1","Covid_Expired":"1","Covid_Region":"Sindh","Covid_Admitted":"1"}]

您应该做的只是修改您的 json 请求。

---

package main

import (
    "bufio"
    "encoding/csv"
    "encoding/json"
    "flag"
    "fmt"
    "io"
    "log"
    "net"
    "os"
)

type CovidPatient struct {
    Positive   string `json:"Covid_Positive"`
    Performed  string `json:"Coivd_Performed"`
    Date       string `json:"Covid_Date"`
    Discharged string `json:"Covid_Discharged"`
    Expired    string `json:"Covid_Expired"`
    Region     string `json:"Covid_Region"`
    Admitted   string `json:"Covid_Admitted"`
}

type DataRequest struct {
    Get CovidPatient `json:"get"`
}

type DataError struct {
    Error string `json:"Covid_error"`
}

func Load(path string) []CovidPatient {
    table := make([]CovidPatient, 0)
    var patient CovidPatient
    file, err := os.Open(path)
    if err != nil {
        panic(err.Error())
    }
    defer file.Close()

    reader := csv.NewReader(file)
    csvData, err := reader.ReadAll()
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    for _, row := range csvData {
        patient.Positive = row[0]
        patient.Performed = row[1]
        patient.Date = row[2]
        patient.Discharged = row[3]
        patient.Expired = row[4]
        patient.Region = row[5]
        patient.Admitted = row[6]
        table = append(table, patient)
    }
    return table
}

func Find(table []CovidPatient, filter CovidPatient) []CovidPatient {

    result := make([]CovidPatient, 0)

    log.Println(filter, table)

    for _, cp := range table {

        if filter.Positive == "" {
        } else if filter.Positive != cp.Positive {
            continue
        }
        if filter.Performed == "" {
        } else if filter.Performed != cp.Performed {
            continue
        }
        if filter.Date == "" {
        } else if filter.Date != cp.Date {
            continue
        }
        if filter.Discharged == "" {
        } else if filter.Discharged != cp.Discharged {
            continue
        }
        if filter.Expired == "" {
        } else if filter.Expired != cp.Expired {
            continue
        }
        if filter.Region == "" {
        } else if filter.Region != cp.Region {
            continue
        }
        if filter.Admitted == "" {
        } else if filter.Admitted != cp.Admitted {
            continue
        }

        result = append(result, cp)
    }
    return result

}

var (
    patientsDetail = Load("./covid_final_data.csv")
)

func main() {
    log.SetFlags(log.Lshortfile | log.Ltime)
    var addr string
    var network string
    flag.StringVar(&addr, "e", ":4040", "service endpoint [ip addr or socket path]")
    flag.StringVar(&network, "n", "tcp", "network protocol [tcp,unix]")
    flag.Parse()

    switch network {
    case "tcp", "tcp4", "tcp6", "unix":
    default:
        fmt.Println("unsupported network protocol")
        os.Exit(1)
    }

    ln, err := net.Listen(network, addr)
    if err != nil {
        log.Println(err)
        os.Exit(1)
    }
    defer ln.Close()
    log.Println("Covid19 Condition in Pakistan")
    log.Printf("Service started: (%s) %s\n", network, addr)

    for {
        conn, err := ln.Accept()
        if err != nil {
            log.Println(err)
            conn.Close()
            continue
        }
        log.Println("Connected to ", conn.RemoteAddr())
        go handleConnection(conn)
    }
}
func handleConnection(conn net.Conn) {
    defer func() {
        if err := conn.Close(); err != nil {
            log.Println("error closing connection:", err)
        }
    }()

    reader := bufio.NewReaderSize(conn, 100)

    for {
        buf, err := reader.ReadBytes('|')
        if err != nil {
            if err != io.EOF {
                log.Println("connection read error:", err)
                return
            }
        }
        reader.Reset(conn)

        var req DataRequest
        if err := json.Unmarshal(buf[:len(buf)-1], &req); err != nil {
            log.Println("failed to unmarshal request:", string(buf), err)
            cerr, jerr := json.Marshal(DataError{Error: err.Error()})
            if jerr != nil {
                log.Println("failed to marshal DataError:", jerr)
                continue
            }
            if _, werr := conn.Write(cerr); werr != nil {
                log.Println("failed to write to DataError:", werr)
                return
            }
            continue
        }

        result := Find(patientsDetail, req.Get)

        rsp, err := json.Marshal(&result)
        if err != nil {
            log.Println("failed to marshal data:", err)
            if _, err := fmt.Fprintf(conn, `{"data_error":"internal error"}`); err != nil {
                log.Printf("failed to write to client: %v", err)
                return
            }
            continue
        }
        if _, err := conn.Write(rsp); err != nil {
            log.Println("failed to write response:", err)
            return
        }
    }
}

查询是：

╭─root@DESKTOP-OCDRD7Q ~
╰─# nc localhost 4040                                                                                             127 ↵
{
    "get": {
        "Covid_Region": "Sindh",
        "Covid_Date": "2020-03-20"
    }
}|
[{"Covid_Positive":"1","Coivd_Performed":"1","Covid_Date":"2020-03-20","Covid_Discharged":"1","Covid_Expired":"1","Covid_Region":"Sindh","Covid_Admitted":"1"}]