Derive Macro tsukuyomi::IntoResponse

#[derive(IntoResponse)]
{
    // Attributes available to this derive:
    #[response]
}

A procedural macro for deriving the implementation of IntoResponse.

Examples

This macro has a parameter #[response(preset = "..")], which specifies the path to a type that implements a trait Preset:

use serde::Serialize;

#[derive(Debug, Serialize, IntoResponse)]
#[response(preset = "tsukuyomi::output::preset::Json")]
struct Post {
    title: String,
    text: String,
}

You can specify the additional trait bounds to type parameters by using the parameter #[response(bound = "..")]:

#[derive(Debug, IntoResponse)]
#[response(
    preset = "tsukuyomi::output::preset::Json",
    bound = "T: Serialize",
    bound = "U: Serialize",
)]
struct CustomValue<T, U> {
    t: T,
    u: U,
}

Notes

1. When preset = ".." is omitted for struct, a field in the specified struct is chosen and the the implementation of IntoResponse for its type is used. For example, the impls derived to the following types outputs eventually the same result as the implementation of IntoResponse for String:

   #[derive(IntoResponse)]
   struct Foo(String);
   
   #[derive(IntoResponse)]
   struct Bar {
       inner: String,
   }

2. When preset = ".." is omitted for enum, the same rule as struct is applied to each variant:

   #[derive(IntoResponse)]
   enum MyResponse {
       Text(String),
       Raw { response: Response<String> },
   }

3. Without specifying the preset, the number of fields in the struct or the number of fields of each variant inside of the enum must be at most one. This is because the field that implements IntoResponse cannot be determined if there are two or more fields in a struct or a variant:

   #[derive(IntoResponse)]
   enum ApiResponse {
       Text(String),
       Post { title: String, text: String },
   }

   If you want to apply the derivation to complex enums, consider cutting each variant into one struct and specifying the preset explicitly as follows:

   #[derive(IntoResponse)]
   enum ApiResponse {
       Text(String),
       Post(Post),
   }
   
   #[derive(Debug, Serialize, IntoResponse)]
   #[response(preset = "tsukuyomi::output::preset::Json")]
   struct Post {
        title: String,
        text: String,
   }