Null key overrides add null rows 2

internal/topdata/native.go

@@ -974,6 +974,10 @@ func collectBaseDataset(dataset nativeDataset) (nativeCollectedDataset, error) {
 						rowByKey[rawKey] = row
 					}
 				}
+				if overrideRequestsNullRow(override) {
+					nullifyOverrideRow(row, columns, rowByKey)
+					continue
+				}
 				candidate := map[string]any{}
 				for field, value := range row {
 					candidate[field] = value
@@ -4058,6 +4062,41 @@ func resolveOverrideTarget(datasetName string, override map[string]any, rowByID
 	return nil, fmt.Errorf("dataset %s: override must specify id or key", datasetName)
 }
 
+func overrideRequestsNullRow(override map[string]any) bool {
+	rawKey, ok := override["key"]
+	if !ok {
+		return false
+	}
+	if rawKey == nil {
+		return true
+	}
+	typed, ok := rawKey.(string)
+	if !ok {
+		return false
+	}
+	return strings.TrimSpace(typed) == nullValue
+}
+
+func nullifyOverrideRow(row map[string]any, columns []string, rowByKey map[string]map[string]any) {
+	if oldKey, ok := row["key"].(string); ok && oldKey != "" {
+		if mapped, exists := rowByKey[oldKey]; exists {
+			mappedID, mappedHasID := mapped["id"].(int)
+			rowID, rowHasID := row["id"].(int)
+			if mappedHasID && rowHasID && mappedID == rowID {
+				delete(rowByKey, oldKey)
+			}
+		}
+	}
+	for field := range row {
+		if field != "id" {
+			delete(row, field)
+		}
+	}
+	for _, column := range columns {
+		row[column] = nullValue
+	}
+}
+
 func updateOverrideRowKey(datasetName string, row map[string]any, expanded map[string]any, rowByKey map[string]map[string]any, lockData map[string]int) (bool, error) {
 	oldKey, _ := row["key"].(string)
 	newKeyValue, hasKey := expanded["key"]