Close the WebSocket when destroying the View of the model

Level: intermediate

To close the WebSocket when destroying the View of the model, add a custom implementation of the crt.HandleViewModelDestroyRequest system query handler to the handlers schema section. The handler is executed when the View of the model is destroyed (for example, when you open another page). Designed to destroy resources. We do not recommend writing asynchronous code in the handler (server calls, timeouts, etc.) except for reading the value of attributes.

View an example of the crt.HandleViewModelDestroyRequest query handler that closes the custom SomeWebSocket WebSocket below.

Freedom UI cannot destroy a View model and loads the last page state when you re-open a previously loaded module. Use the crt.HandleViewModelPauseRequest handler called every time you open a different page. The crt.HandleViewModelDestroyRequest and crt.HandleViewModelPauseRequest handlers use the same data.

handlers schema section

handlers: /**SCHEMA_HANDLERS*/[
    {
        request: "crt.HandleViewModelPauseRequest",
        /* Custom implementation of a system query handler. */
        handler: async (request, next) => {
            /* Close the SomeWebSocket WebSocket */
            (await request.$context.SomeWebSocket).close();
            /* Call the next handler if it exists and return its result. */
            return next?.handle(request);
        }
    }
]/**SCHEMA_HANDLERS*/,