Ask some registration questions of students only

Every account-signup question was asked of everybody who registered, on the
same terms: "school and grade" had to be put to an adult signing themselves
up, and a question a studio needed answered for each student could only be
made required by demanding it of everyone.

A question now carries an audience — everyone, or only the students someone
registers on behalf of — and its own required flag for each side, so optional
for you and required for every student you enrol is expressible. Both settings
are account-scope only: an offering asks its questions once, about the student
being booked, so there is no second audience to differ from, and an offering
question mirrors its single "required" into both columns.

Every caller reads askedOfSelf()/isRequiredForSelf()/isRequiredForChild()
rather than the raw flags, so a students-only question can neither block the
account holder nor have an answer filed against them by a crafted post. The
family screen, which only ever adds a student, is held to the students' rule.

is_required_child arrives from dbDelta defaulting to 0, which would quietly
stop every existing required question being required of the students a
guardian registers — the case it most likely existed for. A one-time backfill
copies is_required across, guarded by its own option so a question later made
optional for students stays that way.

Closes #163

Co-Authored-By: Claude Opus 5 <[email protected]>

src/Auth/RegistrationPage.php

@@ -319,6 +319,13 @@ class RegistrationPage {
 		// student themselves. "Both" is both.
 		$registeringFor = $this->submittedRegisteringFor();
 
+		// A "students only" question is never put to the account holder, so it is
+		// dropped before their answers are validated or stored — a crafted post
+		// cannot file one against them.
+		$selfQuestions = array_values(
+			array_filter( $accountQuestions, static fn( Question $question ): bool => $question->askedOfSelf() )
+		);
+
 		// "Students" and "both" collect student blocks; only "self" does not.
 		$isGuardian = self::FOR_SELF !== $registeringFor;
 
@@ -355,7 +362,7 @@ class RegistrationPage {
 		// Checked as two passes rather than one so the message can say *whose*
 		// answers are missing — under "both" a single message could not.
 		foreach ( array_column( $children, 'answers' ) as $set ) {
-			if ( $this->hasUnansweredRequired( $accountQuestions, $set ) ) {
+			if ( $this->hasUnansweredRequired( $accountQuestions, $set, forChild: true ) ) {
 				return esc_html__( 'Please answer all required registration questions for each student.', 'unsupervised-schedular' );
 			}
 		}
@@ -369,7 +376,7 @@ class RegistrationPage {
 			return esc_html( GuardianService::ownBirthYearError() );
 		}
 
-		if ( $asksSelf && $this->hasUnansweredRequired( $accountQuestions, $answers ) ) {
+		if ( $asksSelf && $this->hasUnansweredRequired( $selfQuestions, $answers ) ) {
 			return esc_html__( 'Please answer all required registration questions.', 'unsupervised-schedular' );
 		}
 
@@ -420,7 +427,7 @@ class RegistrationPage {
 		// After the children, so a rollback that deletes this account cannot
 		// leave its answers behind pointing at a user that no longer exists.
 		if ( $asksSelf ) {
-			$this->recordAnswers( $accountQuestions, $answers, (int) $userId );
+			$this->recordAnswers( $selfQuestions, $answers, (int) $userId );
 		}
 
 		if ( $inviteValid && ! $invite->isGroup() ) {
@@ -564,12 +571,18 @@ class RegistrationPage {
 	/**
 	 * Whether any required question in `$questions` is left blank in `$answers`.
 	 *
+	 * `$forChild` picks which required-ness applies: a question can be optional
+	 * for the account holder answering about themselves and still required of
+	 * every student they register.
+	 *
 	 * @param list<Question>      $questions
 	 * @param array<int, string>  $answers
 	 */
-	private function hasUnansweredRequired( array $questions, array $answers ): bool {
+	private function hasUnansweredRequired( array $questions, array $answers, bool $forChild = false ): bool {
 		foreach ( $questions as $question ) {
-			if ( $question->isRequired && '' === trim( (string) ( $answers[ (int) $question->id ] ?? '' ) ) ) {
+			$required = $forChild ? $question->isRequiredForChild() : $question->isRequiredForSelf();
+
+			if ( $required && '' === trim( (string) ( $answers[ (int) $question->id ] ?? '' ) ) ) {
 				return true;
 			}
 		}