From 7ec97f4ad82d45be9a1ecb1d49fd2f94a7aff81f Mon Sep 17 00:00:00 2001
From: Sven Grossmann <sven.grossmann@grafana.com>
Date: Thu, 15 Feb 2024 16:28:05 +0100
Subject: [PATCH] Loki: Fix fetching of label names if no previous equality
 operator (#82582)

---
 .../components/LokiQueryBuilder.test.tsx      | 21 +++++++++++++++++++
 .../components/LokiQueryBuilder.tsx           |  5 ++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.test.tsx b/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.test.tsx
index 96d7fe3cb80..8ba6538dcdb 100644
--- a/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.test.tsx
+++ b/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.test.tsx
@@ -107,6 +107,27 @@ describe('LokiQueryBuilder', () => {
     expect(props.datasource.languageProvider.fetchSeriesLabels).not.toBeCalled();
   });
 
+  it('uses fetchLabels preselected label have regex equality matcher with match everything value (.*)', async () => {
+    const props = createDefaultProps();
+    props.datasource.getDataSamples = jest.fn().mockResolvedValue([]);
+    props.datasource.languageProvider.fetchSeriesLabels = jest.fn();
+    props.datasource.languageProvider.fetchLabels = jest.fn().mockReturnValue(['a', 'b']);
+
+    const query: LokiVisualQuery = {
+      labels: [
+        { op: '=~', label: 'cluster', value: '.*' },
+        { op: '=', label: 'job', value: 'grafana' },
+      ],
+      operations: [],
+    };
+    render(<LokiQueryBuilder {...props} query={query} />);
+    const labels = screen.getByText(/Label filters/);
+    const selects = getAllByRole(getSelectParent(labels)!, 'combobox');
+    await userEvent.click(selects[3]);
+    expect(props.datasource.languageProvider.fetchLabels).toBeCalledWith({ timeRange: mockTimeRange });
+    expect(props.datasource.languageProvider.fetchSeriesLabels).not.toBeCalled();
+  });
+
   it('uses fetchSeriesLabels preselected label have regex equality matcher', async () => {
     const props = createDefaultProps();
     props.datasource.getDataSamples = jest.fn().mockResolvedValue([]);
diff --git a/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.tsx b/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.tsx
index dd6ddbf015e..f112874988d 100644
--- a/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.tsx
+++ b/public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.tsx
@@ -58,7 +58,10 @@ export const LokiQueryBuilder = React.memo<Props>(
     const onGetLabelNames = async (forLabel: Partial<QueryBuilderLabelFilter>): Promise<string[]> => {
       const labelsToConsider = query.labels.filter((x) => x !== forLabel);
 
-      if (labelsToConsider.length === 0) {
+      const hasEqualityOperation = labelsToConsider.find(
+        (filter) => filter.op === '=' || (filter.op === '=~' && new RegExp(filter.value).test('') === false)
+      );
+      if (labelsToConsider.length === 0 || !hasEqualityOperation) {
         return await datasource.languageProvider.fetchLabels({ timeRange });
       }