Returns an unknown type in Rust - json

Question

From a deserialized JSON file into structures,
{
"infos": {
"info_example": {
"title": {
"en": "Title for example",
"fr": "Titre pour l'exemple"
},
"message": {
"en": "Message for example"
}
}
},
"errors": {}
}
#[derive(Debug, Deserialize)]
struct Logs {
infos: Infos,
errors: Errors,
}
#[derive(Debug, Deserialize)]
struct Infos {
info_example: Log,
}
#[derive(Debug, Deserialize)]
struct Errors {}
#[derive(Debug, Deserialize)]
struct Log {
title: MultiString,
message: MultiString,
}
#[derive(Debug, Deserialize)]
struct MultiString {
en: String,
fr: Option<String>,
de: Option<String>
}
I would like to create a function working like this :
logs_manager.get("infos.info_example.message.en")
struct LogsManager {
logs: Logs
}
impl LogsManager {
fn get(&self, element: &str) -> T {
let splitted: Vec<&str> = element.split(".").collect();
// Later it will be a loop, but for now I'm just gonna take the first part
match splitted[0] {
"infos" => {
&self.logs.infos
},
"errors" => {
&self.logs.errors
}
_ => panic!()
}
}
}
When I try to compile, I'm getting these errors :
Compiling so_question_return_type v0.1.0 (/run/media/anton/data120/Documents/testa)
error[E0308]: mismatched types
--> src/main.rs:26:17
|
20 | fn get<T>(&self, element: &str) -> &T {
| - this type parameter -- expected `&T` because of return type
...
26 | &self.logs.infos
| ^^^^^^^^^^^^^^^^ expected type parameter `T`, found struct `Infos`
|
= note: expected reference `&T`
found reference `&Infos`
error[E0308]: mismatched types
--> src/main.rs:29:17
|
20 | fn get<T>(&self, element: &str) -> &T {
| - this type parameter -- expected `&T` because of return type
...
29 | &self.logs.errors
| ^^^^^^^^^^^^^^^^^ expected type parameter `T`, found struct `Errors`
|
= note: expected reference `&T`
found reference `&Errors`
For more information about this error, try `rustc --explain E0308`.
error: could not compile `so_question_return_type` due to 2 previous errors
try compile by yourself thanks to this file : https://gist.github.com/antoninhrlt/feee9ec4da1cb0edd0e7f426a6c744b0
So, I've tried to create an enum variant to avoid the type return problem.
enum LogObject<'a> {
Logs(Logs),
Infos(Infos),
Errors(Errors),
Log(Log),
MultiString(MultString)
}
Then I wrap the object I want to return into a LogObject. See :
"infos" => {
StringsObject::Logs(&self.logs.infos)
}
It works. But I would like to easily retrieve the value inside the enum object.
impl<'a> LogsObject<'a> {
fn retrieve_object<T>(&self) -> &T {
match *self {
Self::Logs(object) => object,
Self::Infos(object) => object,
Self::Errors(object) => object,
Self::Log(object) => object,
Self::MultiString(object) => object,
}
}
}
But this gives me another error :
error[E0308]: mismatched types
--> crates/strings/src/manager.rs:63:44
|
61 | fn retrieve_object<T>(&self) -> &T {
| - -- expected `&T` because of return type
| |
| this type parameter
62 | match *self {
63 | Self::Logs(object) => object,
| ^^^^^^ expected type parameter `T`, found struct `structured::Logs`
|
= note: expected reference `&T`
found reference `&structured::Logs`
For more information about this error, try `rustc --explain E0308`.
error: could not compile `strings` due to previous error
I'm lost, I don't know how to implement that. So after searching for a while, I'm asking to you.
Does anyone know how to do this ?
PS : I'm using serde for deserialization.

Answer 1

Making a get function was a bad idea.
Now, I'm simply doing something like that :
logs_manager.logs.info_example.message.en
Other thing, I'm including the json file into the binary thanks to include_str!
Thank you the reply, but I think it's better to abandon my first idea