From 0d803613d6d0e8915c9a8cb75951f647bd4c9a3c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=A4ggmark?= <hugo.haggmark@grafana.com>
Date: Wed, 28 Oct 2020 08:04:30 +0100
Subject: [PATCH] StatPanel: Fixes BizChart error max: yyy should not be less
 than min zzz (#28587)

---
 .../src/field/fieldOverrides.test.ts          | 19 ++++++++++++++++--
 .../grafana-data/src/field/fieldOverrides.ts  | 20 +++++++++++++++----
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/packages/grafana-data/src/field/fieldOverrides.test.ts b/packages/grafana-data/src/field/fieldOverrides.test.ts
index f7e26bfadbc..44084927f6f 100644
--- a/packages/grafana-data/src/field/fieldOverrides.test.ts
+++ b/packages/grafana-data/src/field/fieldOverrides.test.ts
@@ -11,14 +11,14 @@ import { MutableDataFrame, toDataFrame } from '../dataframe';
 import {
   DataFrame,
   Field,
+  FieldColorModeId,
   FieldConfig,
   FieldConfigPropertyItem,
   FieldConfigSource,
   FieldType,
   InterpolateFunction,
-  ThresholdsMode,
-  FieldColorModeId,
   ScopedVars,
+  ThresholdsMode,
 } from '../types';
 import { locationUtil, Registry } from '../utils';
 import { mockStandardProperties } from '../utils/tests/mockStandardProperties';
@@ -87,6 +87,21 @@ describe('Global MinMax', () => {
     expect(minmax.min).toEqual(-20);
     expect(minmax.max).toEqual(1234);
   });
+
+  describe('when value is null', () => {
+    it('then global min max should be null', () => {
+      const frame = toDataFrame({
+        fields: [
+          { name: 'Time', type: FieldType.time, values: [1] },
+          { name: 'Value', type: FieldType.number, values: [null] },
+        ],
+      });
+      const { min, max } = findNumericFieldMinMax([frame]);
+
+      expect(min).toBeNull();
+      expect(max).toBeNull();
+    });
+  });
 });
 
 describe('applyFieldOverrides', () => {
diff --git a/packages/grafana-data/src/field/fieldOverrides.ts b/packages/grafana-data/src/field/fieldOverrides.ts
index fad547fc982..f1bd357e47f 100644
--- a/packages/grafana-data/src/field/fieldOverrides.ts
+++ b/packages/grafana-data/src/field/fieldOverrides.ts
@@ -55,11 +55,23 @@ export function findNumericFieldMinMax(data: DataFrame[]): GlobalMinMax {
     for (const field of frame.fields) {
       if (field.type === FieldType.number) {
         const stats = reduceField({ field, reducers });
-        if (stats[ReducerID.min] < min) {
-          min = stats[ReducerID.min];
+        const statsMin = stats[ReducerID.min];
+        const statsMax = stats[ReducerID.max];
+
+        if (!statsMin) {
+          min = statsMin;
         }
-        if (stats[ReducerID.max] > max) {
-          max = stats[ReducerID.max];
+
+        if (!statsMax) {
+          max = statsMax;
+        }
+
+        if (statsMin && statsMin < min) {
+          min = statsMin;
+        }
+
+        if (statsMax && statsMax > max) {
+          max = statsMax;
         }
       }
     }