无法通过golang orm库创建关联

huangapple
go评论107阅读模式
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：

  1. package main
  3. import (
  4. 	"database/sql"
  5. 	"log"
  7. 	"github.com/jinzhu/gorm"
  8. 	"github.com/mattn/go-sqlite3"
  9. )
  11. var db gorm.DB
  13. type User struct {
  14. 	Name   string
  15. 	Mail   Email
  16. }
  18. type Email struct {
  19. 	Address string
  20. }
  22. //初始化数据库
  23. func InitDB() {
  24. 	var DB_DRIVER string
  25. 	sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
  26. 	log.Printf("Initializing Database with ", DB_DRIVER)
  27. 	dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
  29. 	var err error
  30. 	db, err = gorm.Open("sqlite3", dbSql)
  32. 	if err != nil {
  33. 		log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
  34. 	}
  36. 	db.LogMode(true)
  37. 	//然后你可以使用`*sql.DB`的函数
  38. 	db.DB().Ping()
  39. 	db.DB().SetMaxIdleConns(10)
  40. 	db.DB().SetMaxOpenConns(100)
  42. 	//禁用表名的复数形式
  43. 	db.SingularTable(true)
  44. }
  46. func InitSchema() {
  47. 	db.CreateTable(&User{}, &Email{})
  48. }
  50. func DoStuff() {
  51. 	user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
  52. 	db.Create(&user)
  53. }
  55. func main() {
  56. 	InitDB()
  57. 	InitSchema()
  58. 	DoStuff()
  59. }

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 :

  1. package main
  3. import (
  4. 	"database/sql"
  5. 	"log"
  7. 	"github.com/jinzhu/gorm"
  8. 	"github.com/mattn/go-sqlite3"
  9. )
  11. var db gorm.DB
  13. type User struct {
  14. 	Name   string
  15. 	Mail   Email
  16. }
  18. type Email struct {
  19. 	Address string
  20. }
  22. //Initialize DB .
  23. func InitDB() {
  24. 	var DB_DRIVER string
  25. 	sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
  26. 	log.Printf("Initializing Database with ", DB_DRIVER)
  27. 	dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
  29. 	var err error
  30. 	db, err = gorm.Open("sqlite3", dbSql)
  32. 	if err != nil {
  33. 		log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
  34. 	}
  36. 	db.LogMode(true)
  37. 	// Then you could invoke `*sql.DB`'s functions with it
  38. 	db.DB().Ping()
  39. 	db.DB().SetMaxIdleConns(10)
  40. 	db.DB().SetMaxOpenConns(100)
  42. 	// Disable table name's pluralization
  43. 	db.SingularTable(true)
  44. }
  46. func InitSchema() {
  47. 	db.CreateTable(&User{}, &Email{})
  48. }
  50. func DoStuff() {
  51. 	user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
  52. 	db.Create(&user)
  53. }
  55. func main() {
  56. 	InitDB()
  57. 	InitSchema()
  58. 	DoStuff()
  59. }

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：

  1. package main
  3. import (
  4. 	"database/sql"
  5. 	"log"
  7. 	"github.com/jinzhu/gorm"
  8. 	"github.com/mattn/go-sqlite3"
  9. )
  11. var db gorm.DB
  13. type User struct {
  14. 	ID     uint `gorm:"primary_key"`
  15. 	Name   string
  16. 	Mail   Email
  17. 	MailID sql.NullInt64
  18. }
  20. type Email struct {
  21. 	ID      uint `gorm:"primary_key"`
  22. 	Address string
  23. }
  25. // 初始化数据库
  26. func InitDB() {
  27. 	var DB_DRIVER string
  28. 	sql.Register(DB_DRIVER, &sqlite3.SQLiteDriver{})
  29. 	log.Printf("Initializing Database with ", DB_DRIVER)
  30. 	dbSql, _ := sql.Open(DB_DRIVER, "simple-sqlite")
  32. 	var err error
  33. 	db, err = gorm.Open("sqlite3", dbSql)
  35. 	if err != nil {
  36. 		log.Fatalf("Got error when connecting to the database, the error is '%v'", err)
  37. 	}
  39. 	db.LogMode(true)
  40. 	// 可以使用 `*sql.DB` 的函数
  41. 	db.DB().Ping()
  42. 	db.DB().SetMaxIdleConns(10)
  43. 	db.DB().SetMaxOpenConns(100)
  45. 	// 禁用表名的复数形式
  46. 	db.SingularTable(true)
  47. }
  49. func InitSchema() {
  50. 	db.CreateTable(&User{}, &Email{})
  51. }
  53. func DoStuff() {
  54. 	user := User{Name: "Jinzhu", Mail: Email{Address: "hello@hello.com"}}
  55. 	db.Create(&user)
  56. }
  58. func main() {
  59. 	InitDB()
  60. 	InitSchema()
  61. 	DoStuff()
  62. }
  64. 注意 `User` 和 `Email` 结构体上的主键以及 `User` 上的外键引用。
  66. <details>
  67. <summary>英文:</summary>
  69. You&#39;re missing your primary/foreign key references for each of your models, here&#39;s the updated code:
  71.     package main
  72.     
  73.     import (
  74.     	&quot;database/sql&quot;
  75.     	&quot;log&quot;
  76.     
  77.     	&quot;github.com/jinzhu/gorm&quot;
  78.     	&quot;github.com/mattn/go-sqlite3&quot;
  79.     )
  80.     
  81.     var db gorm.DB
  82.     
  83.     type User struct {
  84.     	ID     uint `gorm:&quot;primary_key&quot;`
  85.     	Name   string
  86.     	Mail   Email
  87.     	MailID sql.NullInt64
  88.     }
  89.     
  90.     type Email struct {
  91.     	ID      uint `gorm:&quot;primary_key&quot;`
  92.     	Address string
  93.     }
  94.     
  95.     //Initialize DB .
  96.     func InitDB() {
  97.     	var DB_DRIVER string
  98.     	sql.Register(DB_DRIVER, &amp;sqlite3.SQLiteDriver{})
  99.     	log.Printf(&quot;Initializing Database with &quot;, DB_DRIVER)
  100.     	dbSql, _ := sql.Open(DB_DRIVER, &quot;simple-sqlite&quot;)
  101.     
  102.     	var err error
  103.     	db, err = gorm.Open(&quot;sqlite3&quot;, dbSql)
  104.     
  105.     	if err != nil {
  106.     		log.Fatalf(&quot;Got error when connecting to the database, the error is &#39;%v&#39;&quot;, err)
  107.     	}
  108.     
  109.     	db.LogMode(true)
  110.     	// Then you could invoke `*sql.DB`&#39;s functions with it
  111.     	db.DB().Ping()
  112.     	db.DB().SetMaxIdleConns(10)
  113.     	db.DB().SetMaxOpenConns(100)
  114.     
  115.     	// Disable table name&#39;s pluralization
  116.     	db.SingularTable(true)
  117.     }
  118.     
  119.     func InitSchema() {
  120.     	db.CreateTable(&amp;User{}, &amp;Email{})
  121.     }
  122.     
  123.     func DoStuff() {
  124.     	user := User{Name: &quot;Jinzhu&quot;, Mail: Email{Address: &quot;hello@hello.com&quot;}}
  125.     	db.Create(&amp;user)
  126.     }
  127.     
  128.     func main() {
  129.     	InitDB()
  130.     	InitSchema()
  131.     	DoStuff()
  132.     }
  134. notice the primary keys on the `User` and `Email` structs as well as the foreign key reference on `User`
  137. </details>

huangapple
  • 本文由 发表于 2015年10月1日 08:46:21
  • 转载请务必保留本文链接：https://go.coder-hub.com/32877813.html
  • go
  • go-gorm
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