Feature: Restrict the backend contract selects 

Description 

Two backend fields let an editor pick a contract: the Contract of a page contact record of fgtclb/academic-contacts4pages , and Selected Contracts of the Profiles: Selected Contracts content element. Both offer every contract of the installation. In an installation with more than one site that is every site's contracts, each labelled with a person's name.

Page TSconfig now restricts a field to the pages its contracts are stored on:

# The "Contract" field of a page contact record.
TCEFORM.tx_academiccontacts4pages_domain_model_contact.contract.itemsProcFunc {
    storagePids = 42,84
    recursive = 1
}

# The "Selected Contracts" field of the content element.
TCEFORM.tt_content.pi_flexform.academicpersons_selectedcontracts.sDEF.settings\.selectedContracts.itemsProcFunc {
    storagePids = 42,84
    recursive = 1
}

storagePids is a comma-separated list of page uids and recursive the number of levels below each of them to include. A hidden folder is included as well, because a storage folder is regularly hidden.

A contract the edited record already references stays selectable wherever it is stored, so that opening and saving a record never drops a relation it has.

Impact 

The setting is opt-in and without it the selects offer what they offered before, so an installation that does not configure it is unaffected.

Respecting the Extbase storage page instead is deliberately not done: a page tree without an explicitly configured storage page would get an empty select and no error.

The restriction is applied before \FGTCLB\AcademicBase\Event\ModifyTcaSelectFieldItemsEvent is dispatched, so a listener of that event still has the last word, including one that adds items back.

Affected Installations 

Installations with contracts in more than one storage folder or site, whose editors pick contracts in the backend.