英文:
Unable to create Associations via golang orm library
问题
我一直在尝试使用golang orm中的关联特性（https://github.com/jinzhu/gorm/），但是无法创建一个非常简单的关联。在下面的示例中，用户表包含数据，但是电子邮件表没有数据。我尝试了很多方法，可能是我漏掉了一些基本的东西，但是在github/stackoverflow上找不到正确的答案。
代码：
package main
import (
"database/sql"
"log"
"github.com/jinzhu/gorm"
"github.com/mattn/go-sqlite3"
)
var db gorm.DB
type User struct {
Name string
Mail Email
}
type Email struct {
Address string
}
//初始化数据库
func InitDB() {
var DB_DRIVER string
sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
log.Printf("Initializing Database with ", DB_DRIVER)
dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
var err error
db, err = gorm.Open("sqlite3", dbSql)
if err != nil {
log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
}
db.LogMode(true)
//然后你可以使用`*sql.DB`的函数
db.DB().Ping()
db.DB().SetMaxIdleConns(10)
db.DB().SetMaxOpenConns(100)
//禁用表名的复数形式
db.SingularTable(true)
}
func InitSchema() {
db.CreateTable(&User{}, &Email{})
}
func DoStuff() {
user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
db.Create(&user)
}
func main() {
InitDB()
InitSchema()
DoStuff()
}
运行go run main.go会输出以下内容：
2015/09/30 17:25:04 Initializing Database with %!(EXTRA string=)
[2015-09-30 17:25:04] [3.21ms] CREATE TABLE "user" ("name" varchar(255))
[2015-09-30 17:25:04] [4.01ms] CREATE TABLE "email" ("address" varchar(255) )
[2015-09-30 17:25:04] [0.54ms] INSERT INTO "user" ("name") VALUES ('Jinzhu')
不确定我漏掉了什么 - 感谢任何回复！
英文:
I've been trying to use the Associations feature in golang orm (https://github.com/jinzhu/gorm/), and am unable to create a pretty simple association.
In the example below, the user table contains data, but email table does not.
I've tried a bunch of things and I'm probably missing something basic, but have been unable to find the right answer in github/stackoverflow.
Code :
package main
import (
"database/sql"
"log"
"github.com/jinzhu/gorm"
"github.com/mattn/go-sqlite3"
)
var db gorm.DB
type User struct {
Name string
Mail Email
}
type Email struct {
Address string
}
//Initialize DB .
func InitDB() {
var DB_DRIVER string
sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
log.Printf("Initializing Database with ", DB_DRIVER)
dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
var err error
db, err = gorm.Open("sqlite3", dbSql)
if err != nil {
log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
}
db.LogMode(true)
// Then you could invoke `*sql.DB`'s functions with it
db.DB().Ping()
db.DB().SetMaxIdleConns(10)
db.DB().SetMaxOpenConns(100)
// Disable table name's pluralization
db.SingularTable(true)
}
func InitSchema() {
db.CreateTable(&User{}, &Email{})
}
func DoStuff() {
user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
db.Create(&user)
}
func main() {
InitDB()
InitSchema()
DoStuff()
}
go run main.go prints the following output
2015/09/30 17:25:04 Initializing Database with %!(EXTRA string=)
[2015-09-30 17:25:04] [3.21ms] CREATE TABLE "user" ("name" varchar(255))
[2015-09-30 17:25:04] [4.01ms] CREATE TABLE "email" ("address" varchar(255) )
[2015-09-30 17:25:04] [0.54ms] INSERT INTO "user" ("name") VALUES ('Jinzhu')
Not sure what I'm missing here - appreciate any response!
答案1
得分: 1
你的模型中缺少主键和外键引用，以下是更新后的代码：
package main
import (
"database/sql"
"log"
"github.com/jinzhu/gorm"
"github.com/mattn/go-sqlite3"
)
var db gorm.DB
type User struct {
ID uint `gorm:"primary_key"`
Name string
Mail Email
MailID sql.NullInt64
}
type Email struct {
ID uint `gorm:"primary_key"`
Address string
}
// 初始化数据库
func InitDB() {
var DB_DRIVER string
sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
log.Printf("Initializing Database with ", DB_DRIVER)
dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
var err error
db, err = gorm.Open("sqlite3", dbSql)
if err != nil {
log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
}
db.LogMode(true)
// 可以使用 `*sql.DB` 的函数
db.DB().Ping()
db.DB().SetMaxIdleConns(10)
db.DB().SetMaxOpenConns(100)
// 禁用表名的复数形式
db.SingularTable(true)
}
func InitSchema() {
db.CreateTable(&User{}, &Email{})
}
func DoStuff() {
user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
db.Create(&user)
}
func main() {
InitDB()
InitSchema()
DoStuff()
}
注意 `User` 和 `Email` 结构体上的主键以及 `User` 上的外键引用。
<details>
<summary>英文:</summary>
You're missing your primary/foreign key references for each of your models, here's the updated code:
package main
import (
"database/sql"
"log"
"github.com/jinzhu/gorm"
"github.com/mattn/go-sqlite3"
)
var db gorm.DB
type User struct {
ID uint `gorm:"primary_key"`
Name string
Mail Email
MailID sql.NullInt64
}
type Email struct {
ID uint `gorm:"primary_key"`
Address string
}
//Initialize DB .
func InitDB() {
var DB_DRIVER string
sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
log.Printf("Initializing Database with ", DB_DRIVER)
dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
var err error
db, err = gorm.Open("sqlite3", dbSql)
if err != nil {
log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
}
db.LogMode(true)
// Then you could invoke `*sql.DB`'s functions with it
db.DB().Ping()
db.DB().SetMaxIdleConns(10)
db.DB().SetMaxOpenConns(100)
// Disable table name's pluralization
db.SingularTable(true)
}
func InitSchema() {
db.CreateTable(&User{}, &Email{})
}
func DoStuff() {
user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
db.Create(&user)
}
func main() {
InitDB()
InitSchema()
DoStuff()
}
notice the primary keys on the `User` and `Email` structs as well as the foreign key reference on `User`
</details>
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论