golang GORM和Gin無法創建具有關聯的對象-Golang-PHP中文網

首頁

後端開發

Golang

golang GORM和Gin無法創建具有關聯的對象

王林

Feb 12, 2024 pm 03:12 PM

golang GORM和Gin无法创建具有关联的对象

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))：

<code>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&#160;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&#160;protected]/context.go:174 (0x8c9ad9)
        (*Context).Next: c.handlers[c.index](c)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email&#160;protected]/recovery.go:102 (0x8c9ac7)
        CustomRecoveryWithWriter.func1: c.Next()
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email&#160;protected]/context.go:174 (0x8c8c7d)
        (*Context).Next: c.handlers[c.index](c)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email&#160;protected]/logger.go:240 (0x8c8c4c)
        LoggerWithConfig.func1: c.Next()
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email&#160;protected]/context.go:174 (0x8c7d3a)
        (*Context).Next: c.handlers[c.index](c)
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email&#160;protected]/gin.go:620 (0x8c79cd)
        (*Engine).handleHTTPRequest: c.Next()
/home/grimm/go/pkg/mod/github.com/gin-gonic/[email&#160;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
</code>

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：

curl http://localhost:8080/v1/product/products --request "POST" --header "Content-Type: application/json" --data @file.json

file.json 的内容：

<code>{
    "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."
    }
}
</code>

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。

<code>
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"`
}
</code>

然后运行

curl http://localhost:8080/v1/product/products --request "POST" --header "Content-Type: application/json" --data @info.json

得到了

<code>{"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."}}}% 
</code>

以上是golang GORM和Gin無法創建具有關聯的對象的詳細內容。更多資訊請關注PHP中文網其他相關文章！

陳述

本文轉載於：stackoverflow。如有侵權，請聯絡admin@php.cn刪除

在Golang和Python之間進行選擇：適合您的項目Apr 19, 2025 am 12:21 AM

golangisidealforperformance-Critical-clitageAppations and ConcurrentPrompromming，而毛皮刺激性，快速播種和可及性。 1）forhigh-porformanceneeds，pelectgolangduetoitsefefsefefseffifeficefsefeflicefsiveficefsiveandconcurrencyfeatures.2）fordataa-fordataa-fordata-fordata-driventriventriventriventriventrivendissp pynonnononesp

Golang：並發和行動績效Apr 19, 2025 am 12:20 AM

Golang通過goroutine和channel實現高效並發：1.goroutine是輕量級線程，使用go關鍵字啟動；2.channel用於goroutine間安全通信，避免競態條件；3.使用示例展示了基本和高級用法；4.常見錯誤包括死鎖和數據競爭，可用gorun-race檢測；5.性能優化建議減少channel使用，合理設置goroutine數量，使用sync.Pool管理內存。

Golang vs. Python：您應該學到哪種語言？Apr 19, 2025 am 12:20 AM

Golang更適合系統編程和高並發應用，Python更適合數據科學和快速開發。 1)Golang由Google開發，靜態類型，強調簡潔性和高效性，適合高並發場景。 2)Python由GuidovanRossum創造，動態類型，語法簡潔，應用廣泛，適合初學者和數據處理。

Golang vs. Python：性能和可伸縮性Apr 19, 2025 am 12:18 AM

Golang在性能和可擴展性方面優於Python。 1)Golang的編譯型特性和高效並發模型使其在高並發場景下表現出色。 2)Python作為解釋型語言，執行速度較慢，但通過工具如Cython可優化性能。

Golang vs.其他語言：比較Apr 19, 2025 am 12:11 AM

Go語言在並發編程、性能、學習曲線等方面有獨特優勢：1.並發編程通過goroutine和channel實現，輕量高效。 2.編譯速度快，運行性能接近C語言。 3.語法簡潔，學習曲線平緩，生態系統豐富。

Golang和Python：了解差異Apr 18, 2025 am 12:21 AM

Golang和Python的主要區別在於並發模型、類型系統、性能和執行速度。 1.Golang使用CSP模型，適用於高並發任務；Python依賴多線程和GIL，適合I/O密集型任務。 2.Golang是靜態類型，Python是動態類型。 3.Golang編譯型語言執行速度快，Python解釋型語言開發速度快。