Architecture

How the parts fit together

QuestionnaireController
    │
    ├── QuestionnaireRepository     → loads the configured questionnaire
    ├── SessionService              → stores / retrieves visitor answers
    ├── ConditionEvaluatorService   → filters questions to the visible subset
    ├── ProgressService             → calculates step X of Y, prev/next uids
    ├── ScoringService              → sums answer option scores
    ├── ResultResolverService       → picks the first matching result page
    │                                 and filters the advice blocks
    └── DomainRecordResolverService → builds the redirect URL for record outcomes

Action flow

GET  /page  →  introAction()      render intro screen
GET  /page  →  questionAction()   render current question
POST /page  →  processAction()    store answer, redirect to next or result
GET  /page  →  resultAction()     resolve result, render or redirect
POST /page  →  resetAction()      clear session, redirect to intro

All five actions are registered as uncached in ext_localconf.php.

Service layer

All business logic lives in Classes/Service/. The services are autowired through Configuration/Services.yaml.

Service	Responsibility
`SessionService`	Reads and writes visitor answers through `FrontendUserAuthentication`. Key `tx_pnquestionnaire`, namespaced per questionnaire uid
`ConditionEvaluatorService`	Iterates all questions, evaluates each condition set, returns the visible questions in sort order
`ProgressService`	`calculate()`, `getNextQuestionUid()`, `getPreviousQuestionUid()`, all operating on the visible questions
`ScoringService`	Traverses visible questions and their answer options, sums the scores. Returns `0.0` when no scores are set
`ResultResolverService`	Iterates result pages top to bottom, returns the first match. Also provides `filterAdviceBlocks()`
`DomainRecordResolverService`	Builds the redirect URL for `domain_record` outcomes with `UriBuilder`, reading the TypoScript target and `foreign_table` from `$GLOBALS['TCA']`
`ResultStorageService`	Writes and retrieves a stored result, and generates its token
`ResultMailService`	Composes and sends the result mail, HTML and plain text
`MailRateLimitService`	Wraps the Symfony rate limiter for the mail form
`StatisticsService`	Increments the start and completion counters

Condition evaluation

Each condition has a condition_type that determines how it is evaluated.

specific_answer (default) passes when the visitor selected a specific answer option for the reference question. Multiple conditions are folded together in list order:

result = evaluate(condition_1)
for each condition_2, condition_3, ...:
    if operator == AND → result = result && evaluate(condition)
    if operator == OR  → result = result || evaluate(condition)

scale_range passes when the numeric answer for the reference question satisfies the configured operator and threshold:

stored_value [operator] scale_value
e.g. 7 >= 5  → true

Supported operators are >=, <=, >, < and =. When the scale question has not been answered yet the condition returns false, so the dependent question stays hidden.

A question is shown when the final combined result is true.

Result page selection

foreach resultPage in questionnaire.resultPages (ordered by sort_order):
    if matches(resultPage, sessionAnswers, totalScore):
        return resultPage  ← first match wins
return null  ← no catch-all configured

Trigger	Match condition
`catch_all`	Always
`score_range`	`scoreMin <= totalScore <= scoreMax`
`specific_answer`	A specific answer option uid appears in the session answers
`combination`	Both `score_range` and `specific_answer` match
`scale_answer`	The numeric answer for the trigger question is within `[triggerScaleMin, triggerScaleMax]`

Session data format

Answers are stored in the TYPO3 frontend session under the root key tx_pnquestionnaire.

tx_pnquestionnaire
└── q_{questionnaireUid}
    └── answers
        ├── "{questionUid}" → ["{answerOptionUid}"]   ← single choice
        ├── "{questionUid}" → ["{uid1}", "{uid2}"]    ← multiple choice
        └── "{questionUid}" → ["{scaleValue}"]        ← scale (raw number)

All values are stored as strings; the SessionService methods handle the conversion.

Extending the extension

Adding a question type

Add the new value to the type select field in Configuration/TCA/tx_pnquestionnaire_question.php — both the items array and the types array.
Add the type constant to Classes/Domain/Model/Question.php.
Create Resources/Private/Partials/AnswerTypes/YourType.html.
Add the mapping to $answerTypePartialMap in QuestionnaireController::questionAction().

No other changes are required.

Adding an outcome type

Add the new value to the outcome_type select field in the result page TCA.
Add the outcome constant to Classes/Domain/Model/ResultPage.php.
Handle it in QuestionnaireController::handleRedirectOutcome() or resultAction().

Replacing a service

To replace or extend the result matching, create a service that extends or wraps ResultResolverService and reconfigure it in Configuration/Services.yaml. The same applies to scoring: your service only needs the same method signature.

public function calculateTotal(array $visibleQuestions, array $sessionAnswers): float

For purely visual changes no PHP is needed at all — copy the Fluid template into your site package, see Templates, styling and JavaScript.