vector - 如何将 Vec 扩展为 HashMap 值？

Question

我有一个 HashMap<String, Vec<String>> .我不知道如何通过增加 Vec 来更新值.我认为以下方法可行:

fn add_employee(mut data: HashMap<String, Vec<String>>) -> HashMap<String, Vec<String>> {
    loop {
        println!("Please enter the name of the employee you would like to manage.");

        let mut employee = String::new();

        io::stdin().read_line(&mut employee).expect(
            "Failed to read line",
        );

        let employee = employee.trim();

        let mut department = String::new();

        println!("Please enter the name of the department you would like to add the employee to.");

        io::stdin().read_line(&mut department).expect(
            "Failed to read line",
        );

        let department = department.trim();

        data.entry(department.to_string())
            .extend(vec![employee.to_string()])
            .or_insert(vec![employee.to_string()]);
    }
}

但它却给出了错误

error: no method named `extend` found for type `std::collections::hash_map::Entry<'_, std::string::String, std::vec::Vec<std::string::String>>` in the current scope
  --> src/main.rs:27:14
   |
27 |             .extend(vec![employee.to_string()])
   |              ^^^^^^

Answer 1

在仔细考虑入口 API 之后，我想到了以下解决方案:

let val = data.entry(department.to_string())
                .or_insert(vec!());

        val.extend(vec!(employee.to_string()));