上门做菜系统的Go语言开发：如何实现订单支付功能？

import (
    "GitHub.com/gin-gonic/gin"
    "gorm.io/driver/Mysql"
    "gorm.io/gorm"
)

type Order struct {
    gorm.Model
    OrderNo  string
    Total    float64
    Status   int
    PayType  string
}

var db *gorm.DB

func initDB() {
    dataSource := "your-database-connection-string"
    db, _ = gorm.Open(mysql.Open(dataSource), &gorm.Config{})
    db.AutoMigrate(&Order{})
}

func PlaceOrder(c *gin.Context) {
    // 解析请求参数
    var order Order
    if err := c.ShouldBindJSON(&order); err != nil {
        c.jsON(Http.StatusBadRequest, gin.H{"error": err.Error()})
        return
    }

    // 生成订单号
    order.OrderNo = generateOrderNo()

    // 保存订单信息到数据库
    result := db.Create(&order)
    if result.Error != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to create order"})
        return
    }

    // 根据支付方式选择支付平台并生成支付链接
    payURL := generatePayURL(order.PayType, order.OrderNo, order.Total)

    // 返回支付链接给客户端
    c.JSON(http.StatusOK, gin.H{"pay_url": payURL})
}

func Callback(c *gin.Context) {
    var callback CallbackData
    if err := c.ShouldBindJSON(&callback); err != nil {
        c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
        return
    }

    // 获取订单信息
    var order Order
    result := db.Where("order_no = ?", callback.OrderNo).First(&order)
    if result.Error != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to find order"})
        return
    }

    // 更新订单状态
    order.Status = callback.Status
    result = db.Save(&order)
    if result.Error != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to update order"})
        return
    }

    // 生成支付成功通知
    notify := generatePayNotify(order)
    // TODO: 发送支付成功通知

    c.JSON(http.StatusOK, gin.H{"message": "Callback successfully processed"})
}

func main() {
    initDB()

    router := gin.Default()
    router.POST("/place-order", PlaceOrder)
    router.POST("/callback", Callback)

    router.Run(":8080")
}