bug fixing

Author: wtao

frontend/src/components/QueryEditor.tsx

@@ -58,7 +58,7 @@ export function QueryEditor(props: Props) {
           });
           const values = await lastValueFrom(response);
           const collections = values.data;
-          if (collections.length > 0) {
+          if (!collection && collections.length > 0) {
             onChange({ ...query, collection: collections[0] });
           }
           setCollections(collections);

frontend/src/datasource.ts

@@ -38,6 +38,7 @@ export class DataSource extends DataSourceApi<MyQuery, MyDataSourceOptions> {
 
   getDefaultQuery(_: CoreApp): Partial<MyQuery> {
     return {
+      collection: '',
       queryText: '',
       queryType: QueryType.timeserie,
     };