async-graphql/docs/en/src/procedural_macros.md

Two ways to define types

I think you have discovered that GraphQL types can be defined using both an attribute macro and a derive.

The following is the corresponding table:

Type	Attribute macro	Derive
Enum	Enum	GQLEnum
Simple Object	SimpleObject	GQLSimpleObject
Input Object	InputObject	GQLInputObject
Interface	Interface	GQLInterface
Union	Union	GQLUnion
Merged Object	MergedObject	GQLMergedObject
Merged Subscription	MergedSubscription	GQLMergedSubscription

The advantage of the attribute macro is that you can provide parameters at the same time, for example：

#[SimpleObject(name = "ABC")]
struct MyObject {
    value: i32,
}

However, attribute macros do not support conditional compilation. The following does not work:

#[SimpleObject]
struct MyObject {
    #[cfg(windows)]
    value: i32,

    #[cfg(not(windows))]
    value: i32,
}

Deriving, on the other hand, does support conditional compilation, but as derive macros can't take parameters you need to provide them separately. For example:

#[derive(SimpleObject)]
#[graphql(name = "ABC")]
struct MyObject {
    value: i32,
}

Which way you use to define types is up to you, personally I prefer to use derive.