Rust Rocket 不匹配的类型

Question

我刚刚从火箭文档中复制了示例并且有错误。

  #![feature(proc_macro_hygiene, decl_macro)]

  #[macro_use]
  extern crate rocket;

  #[get("/person/<name>?<age>")]
  fn person(name: String, age: u8) -> String {
      let mike = uri!(person: "Mike Smith", 28);

      assert_eq!(mike.to_string(), "/person/Mike%20Smith?age=28");
  }

  fn main() {
      rocket::ignite().mount("/", routes![person]).launch();
  }

错误信息：

main.rs|7 col 37 error| mismatched types expected struct `std::string::String`, found () note: expected type `std::string::String` found type `()` [E0308]                         
main.rs|7 col 4 info| mismatched types implicitly returns `()` as its body has no tail or `return` expression note: expected type `std::string::String` found type `()` [E0308]

为什么从示例中复制会给我错误？

这是我的第一篇文章：欢呼：

Answer 1

它在抱怨是因为您指定了返回类型，而不是返回它。 当我运行这段代码时，编译器给出了一个更有帮助的答案，你下次应该在你的问题中包含一些内容：

$> cargo run
. . .
error[E0308]: mismatched types
 --> src/main.rs:7:37
  |
7 | fn person(name: String, age: u8) -> String {
  |    ------                           ^^^^^^ expected struct `std::string::String`, found `()`
  |    |
  |    implicitly returns `()` as its body has no tail or `return` expression

error: aborting due to previous error

要么要返回String类型，要么将返回类型转换为函数：

#[get("/person/<name>?<age>")]
fn person(name: String, age: u8) -> () {
    let mike = uri!(person: "Mike Smith", 28);
    assert_eq!(mike.to_string(), "/person/Mike%20Smith?age=28");

    // or leave the return type as string, but return a string
    //return name
}