How to use set_data in Rust

Development Core
1

I’m trying to use set/get data on a widget. In one function I do:

let a_string: String = dataobj.uuid();
unsafe {
   label.set_data("some_string", a_string);
}

In different function I use

let a_string = unsafe {
            closest
                .first_child()
                .unwrap()
                .first_child()
                .unwrap()
                .data::<String>("some_string")
                .unwrap()
                .read()
        };
println!("aaaa {:?}", a_string);

It sometimes works, but sometimes a_string is some noise and println panics. I’d assume it’s pointer to a_string on the stack being saved via set_data, and therefore it crashes. But how else am I supposed to make it work? I haven’t found any examples in Rust.