泛型支持

[helphi]

Your Question

golang 1.18 泛型beta版已出，请问何时发布 gorm 3.0

Expected answer

跟随golang1.18发布

[FlameMida]

只能说期待了

[zhuying412]

有任何消息吗？

[a631807682]

Gorm uses a lot of reflection and uses different logic under different parameter types, it is not suitable for using templates.
So the question is, how should we modify the API so that generics can bring benefits to users?

[helphi]

eg.

before

var user User
db.First(&user)

after

user := db.First[User]()

[jinzhu]

eg.

before

var user User
db.First(&user)

after

user := db.First[User]()

But with the new style, you can't reuse a variable to reduce GC.

[helphi]

我觉得这个就要看用户在使用过程中如何取舍了，泛型这么多年才出来官方本来也是在性能与便捷之间进行取舍，gorm支持泛型至少表示我们还是跟着主旋律走的噻 ...

[jinzhu]

There is no doubt, we will support generics, but for the above change, I don't see much value, especially it is a breaking changes.

[helphi]

我这里只是随便举的一个例子，表示gorm看能不能通过泛型让大家少写点代码，不能当真，最终肯定要根据实际情况来噻。

[zhuying412]

Is there a roadmap or scheme about supporting generics?

[a631807682]

I don't think generics are needed from the current api design, like database/sql and encoding/json.
At the moment I haven't figured out how to use generics to make the new api more user-friendly, any suggestions?

[yafeng-Soong]

大家可以看看我搞的泛型分页封装示例，风格类似MyBatis-plus，博客https://juejin.cn/post/7078279187471679518，代码https://github.com/yafeng-Soong/blog-example/tree/main/gorm_page_generic
希望能有所帮助

Hey Guys，I wrote a simple example using generic, the style looks like Java's MyBatis-plus. blog——https://juejin.cn/post/7078279187471679518, Code——https://github.com/yafeng-Soong/blog-example/tree/main/gorm_page_generic
Hope to help you.

[a631807682]

The reason why pagination can use generics is that they have the same logic.
Take db.Find as an example, the model of each user cannot be the same, so we use reflection, of course we can convert everything into generics like this, but is it better?

// Find
func Find[T interface{}]() ([]T, error) {
	...
}

users, err := Find[User]()

// Unmarshal
type GenericsJSon[T interface{}] struct {
}

func (g GenericsJSon[T]) Unmarshal(data []byte) (*T, error) {
	...
}

user, err := GenericsJSon[User]{}.Unmarshal([]byte(`{"name":"abc"}`))

For me, there are some API that can use generics like Offset/Limit/Count..., but others need to be discussed.

[yafeng-Soong]

The reason why pagination can use generics is that they have the same logic. Take db.Find as an example, the model of each user cannot be the same, so we use reflection, of course we can convert everything into generics like this, but is it better?

// Find
func Find[T interface{}]() ([]T, error) {
	...
}

users, err := Find[User]()

// Unmarshal
type GenericsJSon[T interface{}] struct {
}

func (g GenericsJSon[T]) Unmarshal(data []byte) (*T, error) {
	...
}

user, err := GenericsJSon[User]{}.Unmarshal([]byte(`{"name":"abc"}`))

For me, there are some API that can use generics like Offset/Limit/Count..., but others need to be discussed.

Thanks for your reply! I got it.

[cheerego]

https://github.com/cheerego/gorm-generics

看看这个