converting a Model to ActiveModel in a function

[mzagrabe]

Hello,

I'm trying to convert a Model into an ActiveModel and I'd like to understand the nuances of doing so inline versus from within a called function.

If I convert "inline", I call:

let active_model: foo::ActiveModel = foo_model.into();

If I try to convert a Model into an ActiveModel in a function, then I need to call something more like:

let mut active_model: foo::ActiveModel = foo_model.clone().into_active_model();

The following code snippet does not compile - as it is a fragment of my larger codebase - but it is abstracted in a way that if I toggle the shall_call_function variable I can change between converting inline versus converting in a function call.

    let mut scrape = scrapes::ActiveModel {
        ..Default::default()
    };

    let scrape: scrapes::Model = scrape.insert(&db_connection).await.expect("Failure");

    let shall_call_function = false;

    let mut scrape: scrapes::ActiveModel = match shall_call_function {
        true  => scrape.into(),
        false => {
            get_active_model(
                &scrape,
            )
                .await
                .unwrap()
        }
    };

    let dt = Local::now();
    scrape.finished_at = Set(Some(dt.into()));
    let scrape: scrapes::Model = scrape.update(&db_connection).await.expect("Failure");

    let close_result = db_connection.close().await;

    Ok(())
}


// {{{ async fn get_active_model
async fn get_active_model(
    scrape: &scrapes::Model,
) -> Result<scrapes::ActiveModel, ()> {
    let mut scrape: scrapes::ActiveModel = scrape.clone().into_active_model();

    Ok(scrape)
}

Why does into() work for the inline conversion, but in the function conversion I need into_active_model() - which takes ownership and thus needs the clone() ?

Thanks for any help!

[sinder38]

If I remember correctly the trait Into<ActiveModel> is only implemented for owned scrapes::Model, not &scrapes::Model. That's it

Inline, the compiler can move the owned value into into(). In your function, you pass a reference, so no matching impl exist and you need .clone() first.

[mzagrabe]

Thanks for the help @sinder38 !

I see that I could do:

let mut scrape = scrape.into_active_model();

or

let mut scrape: scrapes::ActiveModel = scrape.into();

and that the resulting code is (probably?) the same. So the into_active_model() method is (again, probably) provided as a convenience to ergonomically avoid the type declaration.