Transformations: Preserve base threshold when using Config from query results (#96781)

* Merge in default threshold base if exists

* Fix tests to not expect default threshold

* Add config from query example to gdev

* Add a test around the merging of thresholds

* Revert "Add config from query example to gdev"

This reverts commit a239224ebb.

* update gdev

* Add note about keeping the base threshold

* Update public/app/features/transformers/docs/content.ts

Co-authored-by: Isabel Matwawana <76437239+imatwawana@users.noreply.github.com>

* Merge in generated code

---------

Co-authored-by: Leon Sorokin <leeoniya@gmail.com>
Co-authored-by: Isabel Matwawana <76437239+imatwawana@users.noreply.github.com>

packages/grafana-data/src/field/__snapshots__/fieldOverrides.test.ts.snap

@@ -0,0 +1,17 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`setFieldConfigDefaults applies the base threshold when one does not exist in the config 1`] = `
+{
+  "mode": "absolute",
+  "steps": [
+    {
+      "color": "red",
+      "value": -Infinity,
+    },
+    {
+      "color": "green",
+      "value": 50,
+    },
+  ],
+}
+`;

packages/grafana-data/src/field/fieldOverrides.test.ts

@@ -730,6 +730,33 @@ describe('setFieldConfigDefaults', () => {
       }
     `);
   });
+
+  it('applies the base threshold when one does not exist in the config', () => {
+    const defaultConfig: FieldConfig = {
+      thresholds: {
+        mode: ThresholdsMode.Absolute,
+        steps: [{ value: -Infinity, color: 'red' }],
+      },
+    };
+
+    const config: FieldConfig = {
+      thresholds: {
+        mode: ThresholdsMode.Absolute,
+        steps: [{ value: 50, color: 'green' }],
+      },
+    };
+
+    const context: FieldOverrideEnv = {
+      data: [],
+      field: { type: FieldType.number } as Field,
+      dataFrameIndex: 0,
+      fieldConfigRegistry: customFieldRegistry,
+    };
+
+    setFieldConfigDefaults(config, defaultConfig, context);
+
+    expect(config.thresholds).toMatchSnapshot();
+  });
 });
 
 describe('setDynamicConfigValue', () => {

packages/grafana-data/src/field/fieldOverrides.ts

@@ -2,7 +2,7 @@ import { isNumber, set, unset, get, cloneDeep } from 'lodash';
 import { useMemo, useRef } from 'react';
 import usePrevious from 'react-use/lib/usePrevious';
 
-import { VariableFormatID } from '@grafana/schema';
+import { ThresholdsMode, VariableFormatID } from '@grafana/schema';
 
 import { compareArrayValues, compareDataFrameStructures } from '../dataframe/frameComparisons';
 import { guessFieldTypeForField } from '../dataframe/processDataFrame';
@@ -347,6 +347,18 @@ export function setFieldConfigDefaults(config: FieldConfig, defaults: FieldConfi
     // Combine the data source links and the panel default config links
     config.links = [...config.links, ...defaults.links];
   }
+
+  // if we have a base threshold set by default but not on the config, we need to merge it in
+  const defaultBaseStep =
+    defaults?.thresholds?.mode === ThresholdsMode.Absolute &&
+    defaults.thresholds?.steps.find((step) => step.value === -Infinity);
+  if (
+    config.thresholds?.mode === ThresholdsMode.Absolute &&
+    !config.thresholds.steps.some((step) => step.value === -Infinity) &&
+    defaultBaseStep
+  ) {
+    config.thresholds.steps = [defaultBaseStep, ...config.thresholds.steps];
+  }
   for (const fieldConfigProperty of context.fieldConfigRegistry.list()) {
     if (fieldConfigProperty.isCustom && !config.custom) {
       config.custom = {};