How to import a Rust method which returns data?

[Jackolix]

Hey,
im trying to get a String List from a Rust method to create Button elements.
I get an error with the import of the rust method which i dont know how to solve.
Error: Unsupported foreign import "customers.rs"

Slint Code:
``
import {fetch_customers} from "customers.rs";
searchBox := ListView {
y: 163px;
width: 180px;
height: 150px;

    for customer in fetch_customers() : Rectangle {
        height: 40px;
        width: parent.width;
        
        Button {
            x: 0;
            text: data.text;
            //color: white;
            width: parent.width;
        }
    }
    opacity: 0;

    animate y {
        duration: 500ms;
    }
}

``

Rust Method:

``pub fn fetch_customers() -> Vec {
let client = Client::new();
let url = "";

let response = client
    .get(url)
    .send()
    .await
    .expect("Failed to send request");

let customers: Vec<Customer> = response
    .json()
    .await
    .expect("Failed to parse response as JSON");

customers
    .into_iter()
    .map(|customer| customer.name)
    .collect()

}
``

Any help is appreciated 🙏
Thanks

[hunger]

You will need to define a Customer struct in Slint:

struct Customer {
   name: string,
   age: int,
}

Then you can have a in property <[Customer]> model; in your main slint component with a list of those customers.

You use that model like this:

    for customer in root.model : Rectangle {
        height: 40px;
        width: parent.width;
        
        Button {
            x: 0;
            text: data.text;
            //color: white;
            width: parent.width;
        }
    }

Then you implement that model on the rust side (the Customer stuct is visible there!) and set it into the slint property.

The benefit of using a model is that you can add/remove/change elements in the model and that will do the right things...

In your approach it would get a fresh array of elements each time it needs to render the customers... which transfers a lot of data and will rerender anything from scratch each time. That is hugely inefficient and will also trash your UI state like scroll location and such.

The docs to a VecModel on the rust side are here: https://releases.slint.dev/1.6.0/docs/rust/slint/struct.vecmodel

There is an example using a VecModel here:

slint/examples/todo/rust/lib.rs

Line 27 in 1a9d09b

let todo_model = Rc::new(slint::VecModel::<TodoItem>::from(vec![

I hope this helps!

[Jackolix]

Thank you!
You helped me alot