@pingfan-hu Wow, that was fast. Thank you. I try to test this new question type as soon as possible.
Just for now, in the demo survey, the matrix question is missing in the overview list of the question types.

Oops, good catch. I'll fix it today.
Yeah please update to our latest version and have a try.

Done. The matrix type is on the list now.

It seems the change in the appearance of the base question ID leads to a new errror in the sd_show_if() function. I receive the error:
`Invalid show_if targets: date_new. These must be question IDs defined in the survey.qmd file.```

For me, it looks like, it's not possible anymore to address the whole question by the ID.

Hmm, this is an interesting issue. I'm not actually sure what the appropriate interface should be for specifying a show_if condition for a matrix type question. Since a matrix question is really a set of multiple questions, using the root question id as part of a show_if condition seems like it wouldn't make sense, as we can't know which specific question was answered. Using the same car_preference example above, I would expect you should need to specify the sub-question in the show_if, like this:

sd_show_if(
  input$car_preference_buy_gasoline == "disagree" ~ "target_question_id"
)

If I tried to just use car_preference in the condition, there is no choice option for that id, so I don't know what I would specify. I think we might just need to clarify in the documentation that for matrix type questions we generate an id for each sub-question in the row argument, which takes the form question_id_row_id.

@StefanMunnes how were you thinking of using the root question id for a matrix type question? Does this make sense?

That's a good point, but I was struggling with the other way around:

sd_show_if(
    input$interessted_buying_car == "yes" ~ "car_preference"
)

I understand the logic why it could make sense to address the single sub-questions, that is definitively useful. But in most cases it should also be possible to reduce the amount of conditions if you want to navigate to the whole questions by the base ID ("car_preference") instead of every single sub-question (e.g. "car_preference_ev" ...).

The other way around, as you presented in your example, is totally fine. In some cases, I would filter in show_if(), when all the subquestions are empty (e.g. length(input$car_preference_buy_gasoline) == 0 && length(input$car_preference_buy_ev) == 0), not sure if you have a shortcut for this case?

Ah I see. Yes, we should be able to use the root id for a matrix question if it is the target of some condition, meaning the entire matrix question will display if some condition is met. @pingfan-hu can you look into both of these situations? That is, 1) allow the root matrix question id to be used as show_if targets, and 2) allow matrix sub questions to be used as show_if conditions. We should update the roxygen as well, maybe using the "details" tag in sd_question to describe this (could also update the question types docs page).

As for the point about testing if all subquestions are empty, I opened a new feature request here

OK, @StefanMunnes , now it's solved. The reason why it used to work and then didn't is because that I removed the root question id from the data sheet. Now it's added back.
I removed it because this root question id will never be answered and will prohibit you from moving on to the next page, if you set all questions being required. My solution is that I eliminated the matrix root question ids from the required logic.

Long story short: you can again apply the root question id, and if you define all questions as required, there won't be any error.

An implementation of sd_show_if() is like this (same as how you desired):

sd_show_if(
    input$interested_buying_car == "yes" ~ "car_preference"
)

Please update our package and try it out:

remotes::install_github("surveydown-dev/surveydown", force = TRUE)