问题内容
我使用 GORM 作为 ORM 以及我的 Golang API 来与我的数据库进行通信。
但是对于创建与数据库关联的实体，代码失败了（DB.Create(&data))：
2023/11/01 20:44:14 [Recovery] 2023/11/01 - 20:44:14 panic recovered:
POST /v1/product/products HTTP/1.1
Host: localhost:8080
Accept: */*
Content-Length: 589
Content-Type: application/json
User-Agent: curl/8.4.0
runtime error: invalid memory address or nil pointer dereference
/usr/lib/go/src/runtime/panic.go:261 (0x452d97)
panicmem: panic(memoryError)
/usr/lib/go/src/runtime/signal_unix.go:861 (0x452d65)
sigpanic: panicmem()
/home/grimm/go/pkg/mod/gorm.io/[email protected]/finisher_api.go:18 (0x926e7c)
(*DB).Create: if db.CreateBatchSize > 0 {
/home/grimm/Documents/beeskill/website/back_end/API_website/main.go:122 (0x99cfab)
CreatingProduct: DB.Create(&data)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/context.go:174 (0x8c9ad9)
(*Context).Next: c.handlers[c.index](c)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/recovery.go:102 (0x8c9ac7)
CustomRecoveryWithWriter.func1: c.Next()
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/context.go:174 (0x8c8c7d)
(*Context).Next: c.handlers[c.index](c)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/logger.go:240 (0x8c8c4c)
LoggerWithConfig.func1: c.Next()
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/context.go:174 (0x8c7d3a)
(*Context).Next: c.handlers[c.index](c)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/gin.go:620 (0x8c79cd)
(*Engine).handleHTTPRequest: c.Next()
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email protected]/gin.go:576 (0x8c74fc)
(*Engine).ServeHTTP: engine.handleHTTPRequest(c)
/usr/lib/go/src/net/http/server.go:2938 (0x6a35ed)
serverHandler.ServeHTTP: handler.ServeHTTP(rw, req)
/usr/lib/go/src/net/http/server.go:2009 (0x69f4d3)
(*conn).serve: serverHandler{c.server}.ServeHTTP(w, w.req)
/usr/lib/go/src/runtime/asm_amd64.s:1650 (0x46ed20)
goexit: BYTE $0x90 // NOP
使用的代码：
package main
import (
"net/http"
"github.com/gin-gonic/gin"
"gorm.io/driver/sqlite"
"gorm.io/gorm"
)
type CategoryProduct struct {
gorm.Model
Title string `json:"title" gorm:"not null"`
Description string `json:"description"`
}
type CreateCategoryProduct struct {
gorm.Model
Title string `json:"title" binding:"required"`
Description string `json:"description" binding:"required"`
}
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
type PriceYearProduct struct {
gorm.Model
Price float64 `json:"price" gorm:"not null"`
Description string `json:"description"`
}
type CreatePriceYearProduct struct {
gorm.Model
Price float64 `json:"price" binding:"required"`
Description string `json:"description" binding:"required"`
}
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
type PriceMounthProduct struct {
gorm.Model
Price float64 `json:"price" gorm:"not null"`
Description string `json:"description"`
}
type CreatePriceMounthProduct struct {
gorm.Model
Price float64 `json:"price" binding:"required"`
Description string `json:"description" binding:"required"`
}
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
// --------------------------------------------------------
type Product struct {
gorm.Model
Name string `json:"name" gorm:"not null"`
Description string `json:"description" gorm:"not null"`
PriceMounthProduct PriceMounthProduct `json:"pricemounth"`
PriceYearProduct PriceYearProduct `json:"priceyear"`
CategoryProduct CategoryProduct `json:"category"`
}
type CreateProduct struct {
gorm.Model
Name string `json:"name" binding:"required"`
Description string `json:"description" binding:"required"`
PriceMounthProduct PriceMounthProduct `json:"pricemounth" binding:"required"`
PriceYearProduct PriceYearProduct `json:"priceyear" binding:"required"`
CategoryProduct CategoryProduct `json:"category" binding:"required"`
}
var DB *gorm.DB
func ConnectDatabase() {
database, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{})
if err != nil {
panic("Failed to connect to database!")
}
// For the product and dependancies of them
err = database.AutoMigrate(&CategoryProduct{}, &PriceYearProduct{}, &PriceMounthProduct{})
if err != nil {
return
}
err = database.AutoMigrate(&Product{})
if err != nil {
return
}
DB = database
}
// POST /v1/products
// Create a product
func CreatingProduct(c *gin.Context) {
// Validate input
var input CreateProduct
if err := c.ShouldBindJSON(&input); err != nil {
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
return
}
data := Product{
Name: input.Name,
Description: input.Description,
PriceYearProduct: input.PriceYearProduct,
PriceMounthProduct: input.PriceMounthProduct,
CategoryProduct: input.CategoryProduct,
}
DB.Create(&data)
c.JSON(http.StatusOK, gin.H{"data": data})
}
func Routes() {
var router = gin.Default()
v1 := router.Group("/v1")
{
//Product CRUD
product := v1.Group("/product")
product.POST("/products", CreatingProduct)
}
err := router.Run(":8080")
if err != nil {
return
}
}
func main() {
ConnectDatabase()
Routes()
}
以及用于发布一些数据的curl命令：
立即学习“go语言免费学习笔记（深入）”；
curl http://localhost:8080/v1/product/products --request "POST" --header "Content-Type: application/json" --data @file.json
file.json 的内容：
{
"name": "airplane simulation",
"description": "airplane simulation for everybody, childrens to adults.",
"priceyear": {
"price": 44.99,
"description": "pay for a year to access on irplane simulation for everybody, childrens to adults."
},
"pricemounth": {
"price": 4.99,
"description": "pay for a mounth to access on irplane simulation for everybody, childrens to adults."
},
"category": {
"title": "Airplane",
"description": "Information cataegorized on airplane."
}
}
我查看了官方文档，但没有更多信息...... 尝试使用创建时的变量进行调试，但一切似乎都很好......
解决方法
运行代码出现错误
[error] invalid field found for struct main.Product's field PriceMounthProduct: define a valid foreign key for relations or implement the Valuer/Scanner interface
gin日志前第一行的错误信息，可能你错过了。
所以修复它，在 Product 结构中添加正确的 foreignkey gorm 标签 就可以了。
type Product struct {
gorm.Model
Name string `json:"name" gorm:"not null"`
Description string `json:"description" gorm:"not null"`
PriceMounthProduct PriceMounthProduct `json:"pricemounth" gorm:"foreignkey:ID"`
PriceYearProduct PriceYearProduct `json:"priceyear" gorm:"foreignkey:ID"`
CategoryProduct CategoryProduct `json:"category" gorm:"foreignkey:ID"`
}
然后运行
curl http://localhost:8080/v1/product/products --request "POST" --header "Content-Type: application/json" --data @info.json
得到了
{"data":{"ID":1,"CreatedAt":"2023-11-02T13:37:24.052228+08:00","UpdatedAt":"2023-11-02T13:37:24.052228+08:00","DeletedAt":null,"name":"airplane simulation","description":"airplane simulation for everybody, childrens to adults.","pricemounth":{"ID":1,"CreatedAt":"2023-11-02T13:37:24.054792+08:00","UpdatedAt":"2023-11-02T13:37:24.054792+08:00","DeletedAt":null,"price":4.99,"description":"pay for a mounth to access on irplane simulation for everybody, childrens to adults."},"priceyear":{"ID":1,"CreatedAt":"2023-11-02T13:37:24.056352+08:00","UpdatedAt":"2023-11-02T13:37:24.056352+08:00","DeletedAt":null,"price":44.99,"description":"pay for a year to access on irplane simulation for everybody, childrens to adults."},"category":{"ID":1,"CreatedAt":"2023-11-02T13:37:24.056585+08:00","UpdatedAt":"2023-11-02T13:37:24.056585+08:00","DeletedAt":null,"title":"Airplane","description":"Information cataegorized on airplane."}}}%
