TYPO3 Core

Daniel Kempf wrote:

In a backend form there are several fields configured by TCA. Some of them are mandatory. Also there are some IRRE fields for adding relations to other tables. In case of adding a new IRRE relation it does kind of deactivate the mandatory validation although some mandatory fields are not filled in.

It would be better not to reload form on changes as long as not all mandatory fields are filled in.

As additional note, the tca of the inline related record has field properties: 'onChange' => 'reload' and 'eval' => 'required'. Example:
[...]

upvote! Because this handling can cause broken Slug entries. For example: You want to generate a Slug based on the title field of an object. When the onChange handling is now fired, then it ignores the mandatory fields and generates a Slug called "default-#####". After that process is done, then it is not possible that the user can update this slug.

This behauviour is also existing in TYPO3 v9

I have the same problem:

...

'employee' => [
    'label' => 'LLL:EXT:xxx/Resources/Private/Language/locallang_db.xlf:employee',
    'config' => [
        'type' => 'select',
        'renderType' => 'selectSingle',
        'foreign_table' => 'fe_users',
        'items' => [['LLL:EXT:core/Resources/Private/Language/locallang_core.xlf:file_upload.actions.all.empty', '']],
        'default' => '',
        'eval' => 'required',
        'minitems' => 0,
        'maxitems' => 1,
    ],
],
...

I have the 'onchange' setting at an other field. If I change it without filling the employee select, i get an error:
2: SQL error: 'Incorrect integer value: '' for column `db`.`tx_xxx_domain_model_xxx`.`employee` at row 1' (tx_xxx_domain_model_xxx:NEW637873aa9e433573083688)

Reloading after filling out all required fields can be a solution. But I would suggest to disable validations and don't save to the DB on reloading: Simply reload the form and refill all fields as before. Validate only on saving.

I know, the setting 'eval' at selectSingle is not documented, but it works.
See: https://forge.typo3.org/issues/60908

Tested with TYPO3 10 and PHP 7.4