Golang中Get API未返回customerId的解决方法

是的，也不完全是。如果你将代码作为文本粘贴到问题中（比较文本“fmt”和代码 "fmt"），双引号会显示为错误的字符。将代码剪切并粘贴到playground中，它们会显示为非法字符 U+201C ‘“’。

请使用“代码”图标或 ```（三个反引号）来包裹你的代码，以降低他人查看你代码的门槛。

你的代码存在几个问题导致无法正确获取customerId：

1. 路由库不匹配：你使用了http.NewServeMux()但尝试使用mux.Vars()，这是gorilla/mux库的功能
2. 路径参数名称不一致：路由定义使用{CustomerId}但结构体字段是CustomerId（注意大小写）

解决方案：

方案1：使用gorilla/mux（推荐）

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "strconv"
    "github.com/gorilla/mux"
)

type Customer struct {
    FullName   string `json:"fullName"`
    City       string `json:"city"`
    ZipCode    string `json:"zipCode"`
    CustomerId int    `json:"customerId"`
}

func main() {
    router := mux.NewRouter()
    router.HandleFunc("/greet", myHandler)
    router.HandleFunc("/customers", customers)
    router.HandleFunc("/customers/{customerId}", getCustomer)
    log.Fatal(http.ListenAndServe("localhost:8080", router))
}

func myHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Hello World, Welcome to the world of GOlang REST API")
}

func getCustomer(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)
    customerId := vars["customerId"]
    
    // 将字符串转换为整数
    id, err := strconv.Atoi(customerId)
    if err != nil {
        http.Error(w, "Invalid customer ID", http.StatusBadRequest)
        return
    }
    
    // 模拟从数据库获取客户数据
    customer := Customer{
        FullName:   "Test Customer",
        City:       "Test City",
        ZipCode:    "12345",
        CustomerId: id,
    }
    
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(customer)
}

func customers(w http.ResponseWriter, r *http.Request) {
    customers := []Customer{
        {FullName: "Alice", City: "Canada", ZipCode: "100090", CustomerId: 12345},
        {FullName: "Bob", City: "Japan", ZipCode: "100095", CustomerId: 90000},
        {FullName: "Marshall", City: "Australia", ZipCode: "100096", CustomerId: 12346},
    }
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(customers)
}

方案2：使用标准库（不使用gorilla/mux）

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "strconv"
    "strings"
)

type Customer struct {
    FullName   string `json:"fullName"`
    City       string `json:"city"`
    ZipCode    string `json:"zipCode"`
    CustomerId int    `json:"customerId"`
}

func main() {
    router := http.NewServeMux()
    router.HandleFunc("/greet", myHandler)
    router.HandleFunc("/customers", customers)
    router.HandleFunc("/customers/", getCustomer) // 注意这里的斜杠
    log.Fatal(http.ListenAndServe("localhost:8080", router))
}

func myHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Hello World, Welcome to the world of GOlang REST API")
}

func getCustomer(w http.ResponseWriter, r *http.Request) {
    // 从URL路径中提取customerId
    pathParts := strings.Split(r.URL.Path, "/")
    if len(pathParts) < 3 {
        http.Error(w, "Customer ID not found", http.StatusBadRequest)
        return
    }
    
    customerId := pathParts[2]
    id, err := strconv.Atoi(customerId)
    if err != nil {
        http.Error(w, "Invalid customer ID", http.StatusBadRequest)
        return
    }
    
    customer := Customer{
        FullName:   "Test Customer",
        City:       "Test City",
        ZipCode:    "12345",
        CustomerId: id,
    }
    
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(customer)
}

func customers(w http.ResponseWriter, r *http.Request) {
    customers := []Customer{
        {FullName: "Alice", City: "Canada", ZipCode: "100090", CustomerId: 12345},
        {FullName: "Bob", City: "Japan", ZipCode: "100095", CustomerId: 90000},
        {FullName: "Marshall", City: "Australia", ZipCode: "100096", CustomerId: 12346},
    }
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(customers)
}

测试方法：

使用curl测试API：

# 获取所有客户
curl http://localhost:8080/customers

# 获取特定客户（使用方案1的gorilla/mux版本）
curl http://localhost:8080/customers/12345

主要修改：

1. 统一使用gorilla/mux或标准库，不要混用
2. 路径参数使用小写（{customerId}而不是{CustomerId}）
3. 添加JSON标签确保正确序列化
4. 正确处理路径参数提取和类型转换