Function paginate_backward 

pub fn paginate_backward<T, F, Fut>(
    fetch_page: F,
) -> impl Stream<Item = Result<T, Error>>
where
    T: 'static,
    F: Fn(Option<String>) -> Fut + Clone + 'static,
    Fut: Future<Output = Result<Page<T>, Error>>,

Creates a backward paginated stream from a fetch function.

Similar to paginate, but iterates backward through pages using has_previous_page and start_cursor instead of has_next_page and end_cursor.

Note: Items within each page are yielded in the order returned by the server. The backward pagination only affects which pages are fetched, not item order within pages.

Requirements

The fetch function must return a Page with has_previous_page and start_cursor populated. The GraphQL query should:

1. Use last and before parameters (instead of first and after for forward pagination)
2. Query hasPreviousPage and startCursor in pageInfo

Page Size

The last parameter specifies how many items to fetch per page. If last exceeds the server’s maximum page size, the request will fail. Query serviceConfig to discover the page size limits:

query {
  serviceConfig {
    defaultPageSize(type: "Query", field: "objects")
    maxPageSize(type: "Query", field: "objects")
  }
}

Example

let stream = paginate_backward(move |cursor| {
    let client = client.clone();
    async move {
        // Query with `last` and `before` parameters
        // and fetch `hasPreviousPage` and `startCursor` in pageInfo
        client.fetch_page_backward(cursor.as_deref()).await
    }
});