Fix DateInput ignores the timezone when given

## Problem

The changes introduced in marmelab#10299 leads to a regression when the field value is an ISO string or date.

The idea of that change was that if the value contains a date, react-admin should always display that date.

This is often not what users want, because a date entered in a US browser than stored in GMT then displayed again will have shifted.

Besides, this is not required to fix marmelab#10197. The fix in marmelab#10299 is the removal of the call to `parse` in `onChange` (in fact, `parse` used to be called twice).

## Solution

Do not strip the timezone data, whether the field value is a string or a date.

Author: fzaninotto

docs/DateInput.md

@@ -26,7 +26,18 @@ import { DateInput } from 'react-admin';
 <DateInput source="published_at" />
 ```
 
-The field value must be a string with the pattern `YYYY-MM-DD` (ISO 8601), e.g. `'2022-04-30'`.
+The field value must be a string using the pattern `YYYY-MM-DD` (ISO 8601), e.g. `'2022-04-30'`. The returned input value will also be in this format, regardless of the browser locale.
+
+`<DateInput>` also accepts values that can be converted to a `Date` object, such as:
+
+- a localized date string (e.g. `'30/04/2022'`),
+- an ISO date string (e.g. `'2022-04-30T00:00:00.000Z'`),
+- a `Date` object, or
+- a Linux timestamp (e.g. `1648694400000`).
+
+In these cases, `<DateInput>` will automatically convert the value to the `YYYY-MM-DD` format. 
+
+**Note**: This conversion may change the date because of timezones. For example, the date string `'2022-04-30T00:00:00.000Z'` in Europe may be displayed as `'2022-04-29'` in Honolulu. If this is not what you want, pass your own [`parse`](./Inputs.md#parse) function to `<DateInput>`.
 
 ## Props
 

packages/ra-ui-materialui/src/input/DateInput.spec.tsx

@@ -103,8 +103,8 @@ describe('<DateInput />', () => {
         it.each([
             '2021-09-11T20:46:20.000+02:00',
             '2021-09-11 20:46:20.000+02:00',
-            '2021-09-11T20:46:20.000-04:00',
-            '2021-09-11 20:46:20.000-04:00',
+            '2021-09-10T20:46:20.000-04:00',
+            '2021-09-10 20:46:20.000-04:00',
             '2021-09-11T20:46:20.000Z',
             '2021-09-11 20:46:20.000Z',
         ])('should accept a value with timezone %s', async publishedAt => {

packages/ra-ui-materialui/src/input/DateInput.stories.tsx

@@ -61,7 +61,7 @@ export const DefaultValue = () => (
             '2021-09-11 20:46:20.000Z',
             new Date('2021-09-11T20:46:20.000+02:00'),
             // although this one is 2021-09-10, its local timezone makes it 2021-09-11 in the test timezone
-            new Date('2021-09-10T20:46:20.000-04:00'),
+            new Date('2021-09-10T23:46:20.000-09:00'),
             new Date('2021-09-11T20:46:20.000Z'),
             1631385980000,
         ].map((defaultValue, index) => (

packages/ra-ui-materialui/src/input/DateInput.tsx

@@ -205,22 +205,22 @@ export type DateInputProps = CommonInputProps &
     Omit<TextFieldProps, 'helperText' | 'label'>;
 
 /**
- * Convert Date object to String, ignoring the timezone.
+ * Convert Date object to String, using the local timezone
  *
  * @param {Date} value value to convert
  * @returns {String} A standardized date (yyyy-MM-dd), to be passed to an <input type="date" />
  */
 const convertDateToString = (value: Date) => {
     if (!(value instanceof Date) || isNaN(value.getDate())) return '';
-    let UTCDate = new Date(value.getTime() + value.getTimezoneOffset() * 60000);
+    let localDate = new Date(value.getTime());
     const pad = '00';
-    const yyyy = UTCDate.getFullYear().toString();
-    const MM = (UTCDate.getMonth() + 1).toString();
-    const dd = UTCDate.getDate().toString();
+    const yyyy = localDate.getFullYear().toString();
+    const MM = (localDate.getMonth() + 1).toString();
+    const dd = localDate.getDate().toString();
     return `${yyyy}-${(pad + MM).slice(-2)}-${(pad + dd).slice(-2)}`;
 };
 
-const dateRegex = /^(\d{4}-\d{2}-\d{2}).*$/;
+const dateRegex = /^\d{4}-\d{2}-\d{2}$/;
 const defaultInputLabelProps = { shrink: true };
 
 /**
@@ -234,14 +234,21 @@ const defaultInputLabelProps = { shrink: true };
  * - a Linux timestamp
  * - an empty string
  *
+ * When it's not a bare date string (YYYY-MM-DD), the value is converted to
+ * this format using the JS Date object.
+ * THIS MAY CHANGE THE DATE VALUE depending on the browser locale.
+ * For example, the string "09/11/2021" may be converted to "2021-09-10"
+ * in Honolulu. This is expected behavior.
+ * If this is not what you want, you should provide your own parse method.
+ *
  * The output is always a string in the "YYYY-MM-DD" format.
  *
  * @example
  * defaultFormat('2021-09-11'); // '2021-09-11'
- * defaultFormat('09/11/2021'); // '2021-09-11'
- * defaultFormat('2021-09-11T20:46:20.000Z'); // '2021-09-11'
- * defaultFormat(new Date('2021-09-11T20:46:20.000Z')); // '2021-09-11'
- * defaultFormat(1631385980000); // '2021-09-11'
+ * defaultFormat('09/11/2021'); // '2021-09-11' (may change depending on the browser locale)
+ * defaultFormat('2021-09-11T20:46:20.000Z'); // '2021-09-11' (may change depending on the browser locale)
+ * defaultFormat(new Date('2021-09-11T20:46:20.000Z')); // '2021-09-11' (may change depending on the browser locale)
+ * defaultFormat(1631385980000); // '2021-09-11' (may change depending on the browser locale)
  * defaultFormat(''); // null
  */
 const defaultFormat = (value: string | Date | number) => {
@@ -256,11 +263,10 @@ const defaultFormat = (value: string | Date | number) => {
         return convertDateToString(value);
     }
 
-    // Valid date strings should be stripped of their time and timezone parts.
+    // Valid date strings (YYYY-MM-DD) should be considered as is
     if (typeof value === 'string') {
-        const matches = dateRegex.exec(value);
-        if (matches) {
-            return matches[1];
+        if (dateRegex.test(value)) {
+            return value;
         }
     }