PR: https://github.com/LimeSurvey/LimeSurvey/pull/1708

@DenisChenu commented on the PR:

for master : we need a better solution : move after setMoveResult ?

We have moved it:

• from StartSurvey(), which is run inside initFirstStep()
• to after setMoveResult

This is the list of steps it does for starting up:

    /**
     * Init session/params values depending of user moves
     *
     * - It init the needed variables for navigation: initFirstStep, initTotalAndMaxSteps, setMoveResult
     * - Then perform all the needed checks before moving:
     *   + did the participant used browser navigation?
     *   + did he pressed clear cancel, is he a confirmed quota?
     *   + Is the previous step set?
     *   + Is the survey finished?
     *   + Are all the answer validated? (like: participant didn't answered to a mandatory question)
     */
    private function initMove()
    {
        $this->initFirstStep(); // If it's the first time user load this survey, will init session and LEM
        $this->initTotalAndMaxSteps();
        $this->checkIfUseBrowserNav(); // Check if user used browser navigation, or relaoded page
        if ($this->sMove != 'clearcancel' && $this->sMove != 'confirmquota') {
            $this->checkPrevStep(); // Check if prev step is set, else set it
            $this->setMoveResult();
            $this->checkClearCancel();
            $this->setPrevStep();
            $this->checkIfFinished();
            $this->setStep();
            $this->saveStartingValues();

Why do we need to move it after setMoveResult()?
Shouldn't it be done before so the EM data is available for setting the move?

To fix https://bugs.limesurvey.org/view.php?id=16482

prefilling value muts be done only when create survey by another way :)

PS :
Another solution : set it to defaultValue on EM ?

I understand now.
So now this ticket and 16482 (but for lsv4) are fixed.

This approach is OK for me!

Finally : i think you're right …

Use default value system are (maybe) not the best solution …

• Prefill : value was set at start of survey even if variables are in last group
• Default : value was set when step happen (for exemple : in last group : set just before submit).

I'm totally unsure on the best solution here … Using defaultvalue seems cool but unsure it the best solution.
https://github.com/LimeSurvey/LimeSurvey/blob/68ce18e22194171e1c56c27f36ad7ce5b34adc8a/application/helpers/expressions/em_manager_helper.php#L7126

Ok, as to start fresh and avoid missunderstandings, I feel comfortable with the latest PR.
What do you think?

if ($this->sSurveyMode != 'survey' && $_SESSION[$this->LEMsessid]['step'] == 0) return;

Yep : seems OK !

Maybe check $this->aSurveyInfo['showwelcome'] ? https://github.com/LimeSurvey/LimeSurvey/blob/79656ae39499fafd8a36c6ee12c5c9649d74df70/application/helpers/SurveyRuntimeHelper.php#L788