better UX/UI

web/src/pages/admin/table_definition/logic.rs

@@ -375,12 +375,12 @@ pub(crate) async fn set_column_alias(
     .await
 }
 
-/// POST /admin/tables/presentation/order — SetColumnPresentation, moving one
-/// column past its neighbour.
+/// POST /admin/tables/presentation/order — SetColumnPresentation, saving the
+/// order staged by the browser.
 ///
 /// Every alias in the request is the name the backend just reported, so this
-/// write cannot rename a column even when the browser's copy of the table is
-/// stale. Only the order it sends comes from the form.
+/// write cannot rename a column. The ids from the browser must be an exact
+/// permutation of the current columns before their order is accepted.
 pub(crate) async fn set_column_order(
     State(state): State<AppState>,
     headers: HeaderMap,
@@ -399,33 +399,38 @@ pub(crate) async fn set_column_order(
         Ok(columns) => columns,
         Err(response) => return response,
     };
-    let Some(index) = columns
+    let current_ids = columns
         .iter()
-        .position(|column| column.column_id == form.column_id)
-    else {
-        let message = tr!(Locale::from_headers(&headers), "td-err-unknown-column");
+        .map(|column| column.column_id)
+        .collect::<std::collections::HashSet<_>>();
+    let submitted_ids = form
+        .column_ids
+        .iter()
+        .copied()
+        .collect::<std::collections::HashSet<_>>();
+    if form.column_ids.len() != columns.len()
+        || submitted_ids.len() != form.column_ids.len()
+        || submitted_ids != current_ids
+    {
+        let message = tr!(Locale::from_headers(&headers), "td-err-invalid-order");
         return refuse(state, headers, inputs, Page::Presentation, message).await;
-    };
-    // A column at the end of the table has nowhere further to go, and the
-    // button that says so is disabled; a request that asks anyway is answered
-    // with the table as it is.
-    let swap_with = match form.direction.as_str() {
-        "up" => index.checked_sub(1),
-        "down" if index + 1 < columns.len() => Some(index + 1),
-        _ => None,
-    };
-    let Some(swap_with) = swap_with else {
-        return respond(state, headers, inputs, Page::Presentation, StatusCode::OK).await;
-    };
+    }
 
-    let mut presentation = columns
+    let columns_by_id = columns
         .iter()
-        .map(|column| ColumnPresentation {
-            column_id: column.column_id,
-            alias: column.name.clone(),
+        .map(|column| (column.column_id, column))
+        .collect::<std::collections::HashMap<_, _>>();
+    let presentation = form
+        .column_ids
+        .iter()
+        .map(|column_id| {
+            let column = columns_by_id[column_id];
+            ColumnPresentation {
+                column_id: *column_id,
+                alias: column.name.clone(),
+            }
         })
-        .collect::<Vec<_>>();
-    presentation.swap(index, swap_with);
+        .collect();
 
     apply_presentation(
         state,