[BUGFIX] Add FormEngine transformation for dbType=datetime in flexforms

The database-to-backend-from transformation for dbType=datetime fields
(which are supposed to be stored in native databse DATETIME fields,
but are stored as datetime strings in flexforms) were not configured.
As a consequence the raw value (not an ISO8601 string, but Date + Time
separated by a space-char) was passed into formengine and incorrectly
interpreted as timestamp, because it failed to be parsed as a ISO8601
date.

Add this configuration and remove the previously erroneously used
timestamp parsing which is no longer needed since #104309 and was
only implicitly used to transform the datetime, which hid
this bug by resolving into an incorrectly created date.
For this invalid case we'll now throw an error instead of hiding
this case with an invalid transformation.

Note that this cleanup is related to #104309, but the issue has
been present before. Prior to #104309 the field was rendered
as "Invalid DateTime", while the switch to ISO8601 in #104309
resulted in an invalid date to be generated:
A flexform value like "1960-01-01 05:42:23" was interpreted as 1960
seconds (unix timestamp) after 1970 which results in a fake-date to be
calculated: 1970-01-01T00:32:40Z (32:40 because 1960s = 32 * 60 + 40).

Releases: main, 13.4, 12.4
Resolves: #105550
Related: #104309
Change-Id: Ibbf4b4e709358247d6eb8d006bedb05818f1d9c2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/86912
Reviewed-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Kienast <akienast@scripting-base.de>
Tested-by: Andreas Kienast <akienast@scripting-base.de>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: core-ci <typo3@b13.com>

Author: bnf

Build/Sources/TypeScript/backend/form-engine-validation.ts

@@ -137,7 +137,6 @@ export default class FormEngineValidation {
    * Format field value
    */
   public static formatValue(type: string, value: string|number): string {
-    let theString = '';
     switch (type) {
       case 'date':
       case 'datetime':
@@ -147,27 +146,16 @@ export default class FormEngineValidation {
         if (value === '' || value === '0') {
           return '';
         }
-
         const isoDt = DateTime.fromISO(String(value), { zone: 'utc' });
-        if (isoDt.isValid) {
-          return isoDt.toISO({ suppressMilliseconds: true });
-        }
-
-        const parsedInt = typeof value === 'number' ? value : parseInt(value, 10);
-        if (isNaN(parsedInt)) {
-          theString = '';
-        } else {
-          const dt = DateTime.fromSeconds(parsedInt, { zone: 'utc' });
-          theString = dt.toISO({ suppressMilliseconds: true });
+        if (!isoDt.isValid) {
+          throw new Error('Invalid ISO8601 DateTime string: ' + value);
         }
-        break;
+        return isoDt.toISO({ suppressMilliseconds: true });
       case 'password':
-        theString = (value) ? FormEngineValidation.passwordDummy : '';
-        break;
+        return (value) ? FormEngineValidation.passwordDummy : '';
       default:
-        theString = value.toString();
+        return value.toString();
     }
-    return theString;
   }
 
   /**

Build/Sources/TypeScript/backend/tests/form-engine-validation-test.ts

@@ -9,10 +9,16 @@ interface FormEngineConfig {
 interface FormatValueData {
   description: string,
   type: string,
-  value: number|string,
+  value: string,
   result: string
 }
 
+interface FormatInvalidValueData {
+  description: string,
+  type: string,
+  value: number|string,
+}
+
 interface ProcessValueData {
   description: string,
   command: string,
@@ -59,24 +65,6 @@ function using(values: (() => Values)|Values, func: (...args: unknown[]) => void
 
 describe('TYPO3/CMS/Backend/FormEngineValidationTest:', () => {
   const formatValueDataProvider: Array<FormatValueData> = [
-    {
-      'description': 'returns empty string with string 0',
-      'type': 'date',
-      'value': '0',
-      'result': ''
-    },
-    {
-      'description': 'returns date with int 0',
-      'type': 'date',
-      'value': 0,
-      'result': '1970-01-01T00:00:00Z'
-    },
-    {
-      'description': 'works for type date with timestamp',
-      'type': 'date',
-      'value': 10000000,
-      'result': '1970-04-26T17:46:40Z'
-    },
     {
       'description': 'works for type date with iso date',
       'type': 'date',
@@ -90,23 +78,17 @@ describe('TYPO3/CMS/Backend/FormEngineValidationTest:', () => {
       'result': '2016-12-02T11:16:06Z'
     },
     {
-      'description': 'returns empty string with non-iso date',
+      'description': 'works for type date with empty value',
       'type': 'date',
-      'value': 'foo',
+      'value': '',
       'result': ''
     },
     {
-      'description': 'works for type datetime',
-      'type': 'datetime',
+      'description': 'works for type date with 0 value',
+      'type': 'date',
       'value': '0',
       'result': ''
     },
-    {
-      'description': 'works for type datetime with timestamp',
-      'type': 'datetime',
-      'value': 10000000,
-      'result': '1970-04-26T17:46:40Z'
-    },
     {
       'description': 'works for type datetime with iso date',
       'type': 'datetime',
@@ -120,35 +102,53 @@ describe('TYPO3/CMS/Backend/FormEngineValidationTest:', () => {
       'result': '2016-12-02T11:16:06Z'
     },
     {
-      'description': 'resolves to empty result for zero value',
+      'description': 'works for type datetime with empty value',
       'type': 'datetime',
-      'value': '0',
+      'value': '',
       'result': ''
     },
     {
-      'description': 'resolves to empty result for invalid value',
+      'description': 'works for type datetime with 0 value',
       'type': 'datetime',
-      'value': 'invalid',
+      'value': '0',
       'result': ''
     },
     {
-      'description': 'works for type time',
+      'description': 'works for type time with iso date',
       'type': 'time',
-      'value': 0,
-      'result': '1970-01-01T00:00:00Z'
+      'value': '2016-12-02T11:16:06Z',
+      'result': '2016-12-02T11:16:06Z'
     },
     {
-      'description': 'works for type time with timestamp',
+      'description': 'works for type time with empty value',
       'type': 'time',
-      'value': 10000000,
-      'result': '1970-04-26T17:46:40Z'
+      'value': '',
+      'result': ''
     },
     {
-      'description': 'works for type time with iso date',
+      'description': 'works for type time with 0 value',
       'type': 'time',
-      'value': '2016-12-02T11:16:06.000Z',
+      'value': '0',
+      'result': ''
+    },
+    {
+      'description': 'works for type timesec with iso date',
+      'type': 'timesec',
+      'value': '2016-12-02T11:16:06Z',
       'result': '2016-12-02T11:16:06Z'
-    }
+    },
+    {
+      'description': 'works for type timesec with empty value',
+      'type': 'timesec',
+      'value': '',
+      'result': ''
+    },
+    {
+      'description': 'works for type timesec with 0 value',
+      'type': 'timesec',
+      'value': '0',
+      'result': ''
+    },
   ];
 
   describe('tests for formatValue', () => {
@@ -161,6 +161,48 @@ describe('TYPO3/CMS/Backend/FormEngineValidationTest:', () => {
     });
   });
 
+  const formatInvalidValueDataProvider: Array<FormatInvalidValueData> = [
+    {
+      'description': 'throws error with int 0',
+      'type': 'date',
+      'value': 0,
+    },
+    {
+      'description': 'throws error for type date with timestamp',
+      'type': 'date',
+      'value': 10000000,
+    },
+    {
+      'description': 'throws error with non-iso date',
+      'type': 'date',
+      'value': 'foo',
+    },
+    {
+      'description': 'throws error for type datetime with timestamp',
+      'type': 'datetime',
+      'value': 10000000,
+    },
+    {
+      'description': 'throws error for invalid value',
+      'type': 'datetime',
+      'value': 'invalid',
+    },
+    {
+      'description': 'throws error for type time with timestamp',
+      'type': 'time',
+      'value': 10000000,
+    },
+  ];
+
+  describe('tests for invalid value to formatValue', () => {
+    using(formatInvalidValueDataProvider, function(testCase: FormatInvalidValueData) {
+      it(testCase.description, () => {
+        FormEngineValidation.initialize(document.createElement('form'));
+        expect(() => FormEngineValidation.formatValue(testCase.type, testCase.value)).to.throw();
+      });
+    });
+  });
+
   const processValueDataProvider: Array<ProcessValueData> = [
     {
       'description': 'works for command alpha with numeric value',