Grafana-UI: Allow <Select /> value to be unset (#32136)

* Fix: Allow <Select /> value to be unset

* clean up

* fix null object in select onChange

* Revert "fix null object in select onChange"

This reverts commit 4b157073884938e5e6a1fac1bbafa7c6017cb361.

* undo onChange arg type change

* fix tests

packages/grafana-ui/src/components/Select/SelectBase.test.tsx

@@ -1,6 +1,7 @@
-import React from 'react';
+import React, { useState } from 'react';
 import { mount, ReactWrapper } from 'enzyme';
 import { render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
 import selectEvent from 'react-select-event';
 import { SelectBase } from './SelectBase';
 import { SelectableValue } from '@grafana/data';
@@ -43,6 +44,25 @@ describe('SelectBase', () => {
     expect(screen.getByLabelText('My select')).toBeInTheDocument();
   });
 
+  it('allows the value to be unset', async () => {
+    const Test = () => {
+      const option = { value: 'test-value', label: 'Test label' };
+      const [value, setValue] = useState<SelectableValue<string> | null>(option);
+
+      return (
+        <>
+          <button onClick={() => setValue(null)}>clear value</button>
+          <SelectBase value={value} onChange={setValue} options={[option]} />
+        </>
+      );
+    };
+
+    render(<Test />);
+    expect(screen.queryByText('Test label')).toBeInTheDocument();
+    userEvent.click(screen.getByText('clear value'));
+    expect(screen.queryByText('Test label')).not.toBeInTheDocument();
+  });
+
   describe('when openMenuOnFocus prop', () => {
     describe('is provided', () => {
       it('opens on focus', () => {

packages/grafana-ui/src/components/Select/types.ts

@@ -60,7 +60,7 @@ export interface SelectCommonProps<T> {
   /** Use a custom element to control Select. A proper ref to the renderControl is needed if 'portal' isn't set to null*/
   renderControl?: ControlComponent<T>;
   tabSelectsValue?: boolean;
-  value?: SelectValue<T>;
+  value?: SelectValue<T> | null;
   /** Sets the width to a multiple of 8px. Should only be used with inline forms. Setting width of the container is preferred in other cases.*/
   width?: number;
   isOptionDisabled?: () => boolean;

packages/grafana-ui/src/components/Select/utils.test.ts

@@ -74,10 +74,14 @@ describe('Select utils', () => {
       expect(cleanValue('test1', optGroup)).toEqual([{ label: 'Group 4 - Option 1', value: 'test1' }]);
       expect(cleanValue(3, options)).toEqual([{ label: 'Option 3', value: 3 }]);
     });
-    it('should return undefined for null/undefined/empty values', () => {
+
+    it('should return null for null values', () => {
+      expect(cleanValue(null, options)).toEqual([null]);
+    });
+
+    it('should return undefined for undefined/empty values', () => {
       expect(cleanValue([undefined], options)).toEqual(undefined);
       expect(cleanValue(undefined, options)).toEqual(undefined);
-      expect(cleanValue(null, options)).toEqual(undefined);
       expect(cleanValue('', options)).toEqual(undefined);
     });
   });

packages/grafana-ui/src/components/Select/utils.ts

@@ -9,7 +9,8 @@ export const cleanValue = (value: any, options: Array<SelectableValue | Selectab
     const filtered = value.filter(Boolean);
     return filtered?.length ? filtered : undefined;
   }
-  if (typeof value === 'object' && value !== null) {
+  if (typeof value === 'object') {
+    // we want to allow null through into here, so the Select value can be unset
     return [value];
   }
   if (typeof value === 'string' || typeof value === 'number') {