在gorm中如何添加枚举类型？

huangapple
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英文:

How can i add enum in gorm?

问题

我正在编写 PostgreSQL 表模式。

  1. type TestTable struct {
  2. 	ID        int    `gorm:"column:id;primaryKey;autoIncrement"`
  3. 	CarType   string `gorm:"column:car_type"`
  4. }

那么我该如何将 "SEDAN"、"HATCHBACK"、"MINIVAN" 等车型添加为 enum 数据类型呢？

英文:

I am writing PostgreSQL table schema.

  1. type TestTable struct {
  2. 	ID        int    `gorm:"column:id;primaryKey;autoIncrement"`
  3. 	CarType   string `gorm:"column:car_type"`
  4. }

So how can i add car types like "SEDAN", "HATCHBACK", "MINIVAN" as enum data type

答案1

得分: 22

假设您正在使用GORM与PostgreSQL。首先，在您的数据库中创建一个类型。

  1. CREATE TYPE car_type AS ENUM (
  2.     'SEDAN',
  3.     'HATCHBACK',
  4.     'MINIVAN'
  5. );

然后，您需要定义以下模型：

  1. import "database/sql/driver"
  3. type carType string
  5. const (
  6.     SEDAN     carType = "SEDAN"
  7.     HATCHBACK carType = "HATCHBACK"
  8.     MINIVAN   carType = "MINIVAN"
  9. )
  11. func (ct *carType) Scan(value interface{}) error {
  12.     *ct = carType(value.([]byte))
  13.     return nil
  14. }
  16. func (ct carType) Value() (driver.Value, error) {
  17.     return string(ct), nil
  18. }
  20. type MyTable struct {
  21.     gorm.Model
  22.     CarType carType `gorm:"type:car_type"`
  23. }
  25. func (MyTable) TableName() string {
  26.     return "my_table"
  27. }

对于MySQL用户，请添加结构标签gorm:或sql:，这样您就不必运行原始查询来在数据库中创建枚举。

  1. CarType carType `gorm:"type:enum('SEDAN', 'HATCHBACK', 'MINIVAN');column:car_type"`

或者

  1. CarType carType `sql:"type:ENUM('SEDAN', 'HATCHBACK', 'MINIVAN')" gorm:"column:car_type"`
英文:

Assuming you are using GORM with PostgreSQL. First in your database create a type.

  1. CREATE TYPE car_type AS ENUM (
  2. 	'SEDAN',
  3. 	'HATCHBACK',
  4. 	'MINIVAN');

Then you will need to define the following model:

  1. import "database/sql/driver"
  3. type carType string
  5. const (
  6. 	SEDAN  carType = "SEDAN"
  7. 	HATCHBACK carType = "HATCHBACK"
  8. 	MINIVAN carType = "MINIVAN"
  9. )
  11. func (ct *carType) Scan(value interface{}) error {
  12. 	*ct = carType(value.([]byte))
  13. 	return nil
  14. }
  16. func (ct carType) Value() (driver.Value, error) {
  17. 	return string(ct), nil
  18. }
  20. type MyTable struct {
  21. 	gorm.Model
  22. 	CarType carType `gorm:"type:car_type"`
  23. }
  25. func (MyTable) TableName() string {
  26. 	return "my_table"
  27. }

Note for MySQL users, you can add struct tag gorm: or sql: so you don't have to run raw query to create enum in the database.

  1. CarType carType `gorm:"type:enum('SEDAN', 'HATCHBACK', 'MINIVAN')";"column:car_type"`

OR

  1. CarType carType `sql:"type:ENUM('SEDAN', 'HATCHBACK', 'MINIVAN')" gorm:"column:car_type"`

答案2

得分: 2

这里是一个不需要事先创建 SQL 类型的解决方案。你可以使用以下代码来定义你的字段标签：

  1. type TestTable struct {
  2.     ID        int     `gorm:"column:id;primaryKey;autoIncrement"`
  3.     CarType   carType `sql:"type:ENUM('SEDAN', 'HATCHBACK', 'MINIVAN')" gorm:"column:car_type"`
  4. }

此外，你还需要为 carType 类型添加 Scan 和 Value 方法：

  1. type carType string
  3. const (
  4. 	SEDAN     carType = "SEDAN"
  5. 	HATCHBACK carType = "HATCHBACK"
  6. 	MINIVAN   carType = "MINIVAN"
  7. )
  9. func (self *carType) Scan(value interface{}) error {
  10. 	*self = carType(value.([]byte))
  11. 	return nil
  12. }
  14. func (self carType) Value() (driver.Value, error) {
  15. 	return string(self), nil
  16. }

希望对你有帮助！

英文:

Edit: someone pointed out this only works with MySQL. I would take my answer down but someone using MySQL may find it helpful.

Here's an answer that doesn't require you to create a SQL type beforehand. My source for this solution was this github issue

For your field tag, use this:

  1. type TestTable struct {
  2.     ID        int     `gorm:"column:id;primaryKey;autoIncrement"`
  3.     CarType   carType `sql:"type:ENUM('SEDAN', 'HATCHBACK', 'MINIVAN')" gorm:"column:car_type"`
  4. }

You'll also need to add the Scan and Value methods attached to your carType type.

  1. type carType string
  3. const (
  4. 	SEDAN carType = "SEDAN"
  5. 	HATCHBACK carType = "HATCHBACK"
  6.     MINIVAN carType = "MINIVAN"
  7. )
  9. func (self *carType) Scan(value interface{}) error {
  10. 	*self = carType(value.([]byte))
  11. 	return nil
  12. }
  14. func (self carType) Value() (driver.Value, error) {
  15. 	return string(self), nil
  16. }

答案3

得分: 1

在这方面，如果你决定采用稍微不同的方法：
你可以将枚举定义为int，并利用iota。然后你可以使用代码生成器来创建SQL的Scaner/Valuer，同时也可以创建JSON/文本表示。
例如：
https://github.com/dmarkham/enumer

英文:

on a side note- if you decide to go with slightly different approach:
you can define your enums as int, and leverage iota. then you can use code generator to create sql Scaner/Valuer but also json/text representations.
for example:
https://github.com/dmarkham/enumer

答案4

得分: 1

为了扩展Nick的答案，我在自动化方面添加了以下内容：

假设你有一个DBClient结构体，你可以创建一个方法来创建这个car类型：

  1. func (psqlClient *DBClient) CreateCarTypeEnum() error {
  2. 	result := psqlClient.db.Exec("SELECT 1 FROM pg_type WHERE typname = 'car_type';")
  4. 	switch {
  5. 	case result.RowsAffected == 0:
  6. 		if err := psqlClient.db.Exec("CREATE TYPE car_type AS ENUM ('SEDAN', 'HATCHBACK', 'MINIVAN');").Error; err != nil {
  7. 			log.Error().Err(err).Msg("Error creating car_type ENUM")
  8. 			return err
  9. 		}
  11.         return nil
  12. 	case result.Error != nil:
  13. 		return result.Error
  15. 	default:
  16. 		return nil
  17. 	}
  18. }
英文:

in order to extend Nick's answer I am adding the following for automation:

Assuming you have DBClient struct, you can create a method that creates this car type:

  1. func (psqlClient *DBClient) CreateCarTypeEnum() error {
  2. 	result := psqlClient.db.Exec("SELECT 1 FROM pg_type WHERE typname = 'car_type';")
  4. 	switch {
  5. 	case result.RowsAffected == 0:
  6. 		if err := psqlClient.db.Exec("CREATE TYPE car_type AS ENUM ('SEDAN', 'HATCHBACK', 'MINIVAN');").Error; err != nil {
  7. 			log.Error().Err(err).Msg("Error creating car_type ENUM")
  8. 			return err
  9. 		}
  11.         return nil
  12. 	case result.Error != nil:
  13. 		return result.Error
  15. 	default:
  16. 		return nil
  17. 	}
  18. }

答案5

得分: 1

就像你在SQL中编写的那样，你可以使用类型和添加任何你想要的数据类型，就像你在SQL中编写的那样。

  1. type MyTable struct {
  2.     CarType string `gorm:"column:car_type;type:enum('SEDAN','HATCHBACK','MINIVAN')" json:"car_type"`
  3. }
英文:

Just like you write in sql, you can use type and add whatever datatype you want like you write in sql.

  1. type MyTable struct {
  2. 	CarType    string `gorm:"column:car_type;type:enum('SEDAN','HATCHBACK','MINIVAN')" json:"car_type"`
  3. }

答案6

得分: 0

更新，不要使用sql:"car_type"，而是使用gorm:"car_type"。而且，你需要手动在数据库中创建自定义的枚举类型。

英文:

An update, it will not work with sql:"car_type" instead use gorm:"car_type". That too once you have manually created the custom enum type into the database.

答案7

得分: -1

https://gorm.io/docs/data_types.html => 实现Scan和Value方法。

如果枚举是由protoc生成的，可以使用这个插件 https://github.com/yangyang5214/protoc-gen-gorm-serializer。

  1. # task.proto
  2. syntax = "proto3";
  4. enum TaskStatus {
  5.   Unknown = 0;
  6.   Running = 1;
  7.   Exiting = 2;
  8.   Pending = 3;
  9. }
  12. # 生成 gorm-serializer.pb.go
  13. protoc --proto_path=. --go_out=paths=source_relative:. --gorm-serializer_out=paths=source_relative:. task.proto
  15. # 使用
  16. type Task struct {
  17. 	gorm.Model
  18. 	Name   string
  19. 	Status example.TaskStatus `gorm:"type:int"`
  20. }
英文:

https://gorm.io/docs/data_types.html => impl Scan & Value methods.

If enum is generated by protoc, can use this plugin

https://github.com/yangyang5214/protoc-gen-gorm-serializer .

  1. # task.proto
  2. syntax = "proto3";
  4. enum TaskStatus {
  5.   Unknown = 0;
  6.   Running = 1;
  7.   Exiting = 2;
  8.   Pending = 3;
  9. }
  12. # gen gorm-serializer.pb.go
  13. protoc --proto_path=.  --go_out=paths=source_relative:. --gorm-serializer_out=paths=source_relative:.  task.proto
  15. # use 
  16. type Task struct {
  17. 	gorm.Model
  18. 	Name   string
  19. 	Status example.TaskStatus `gorm:"type:int"`
  20. }

huangapple
  • 本文由 发表于 2021年8月3日 21:48:30
  • 转载请务必保留本文链接：https://go.coder-hub.com/68637265.html
  • go
  • go-gorm
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