无法通过Golang Orm库创建关联

Question

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: "[e-mail]"}}
    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!

Answer 1

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: "[e-mail]"}}
    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