controllers/helpers/pagination: Maintain consistent ordering from page to page

For instance, given rows with the following:

| a | b | c | ... | 1 | 2 | 3 |

When performing forward seek pagination with page size as 3 to the last
page, let's say we have the last page as 1, 2, 3. When performing
backward seek pagination, we reverse the order of the query so that we
can retrieve the data from the tail. This results in 3, 2, 1. However,
we would like to maintain consistent ordering as we view it with forward
pagination, namely 1, 2, 3. Therefore, we need to reverse the results
again to maintain the original ordering.

Author: eth3lbert

src/controllers/helpers/pagination.rs

@@ -313,9 +313,12 @@ impl<T> PaginatedQuery<T> {
         let future = self.internal_load(conn);
 
         async move {
-            let records_and_total = future.await?.try_collect().await?;
+            let mut records_and_total: Vec<_> = future.await?.try_collect().await?;
 
-            // TODO: maintain consistent ordering from page to pagen
+            // This maintain consistent ordering from page to pagen
+            if options.is_backward() {
+                records_and_total.reverse();
+            }
 
             Ok(Paginated {
                 records_and_total,
@@ -467,9 +470,12 @@ impl<T, C> PaginatedQueryWithCountSubq<T, C> {
         let future = self.internal_load(conn);
 
         async move {
-            let records_and_total = future.await?.try_collect().await?;
+            let mut records_and_total: Vec<_> = future.await?.try_collect().await?;
 
-            // TODO: maintain consistent ordering from page to pagen
+            // This maintain consistent ordering from page to pagen
+            if options.is_backward() {
+                records_and_total.reverse();
+            }
 
             Ok(Paginated {
                 records_and_total,