Adding ranking and sorting (drag and drop) question types

[Sunilshah-7]

Description

Hi, GW OSPO is building a survey using surveydown where respondents drag software cards into different bins. Since there's no native question type for this, I ended up using sortable::bucket_list() with sd_question_custom() plus a bunch of manual code to serialize the bin state and push it into session$userData$all_data so it actually gets saved to the database. It works, but it's around 100 lines of app code for one question and it touches package internals.

After talking with the team about this and we sketched out what a native version could look like. This picks up where PR #163 left off, without using sortable. I'd like to work on PR for it, but wanted to open this issue first to agree on the API.

Proposed API

A ranking type, where you drag items into an order:

sd_question(
  type  = 'ranking',
  id    = 'albums_ranked',
  label = "Rank these Taylor Swift albums from favorite to least favorite:",
  option = c(
    "Taylor Swift (2006)" = "swift",
    "Fearless (2008)"     = "fearless",
    "Speak Now (2010)"    = "speak_now",
    "Red (2012)"          = "red",
    "1989 (2014)"         = "1989"
  )
)

And a sorting type, where you drag items into bins:

sd_question(
  type  = 'sorting',
  id    = 'albums_sorted',
  label = "Sort these Taylor Swift albums:",
  option = c(...),  # same as above
  bins = c(
    "Love it" = 'love_it',
    "Hate it" = 'hate_it'
  ),
  bin_position = 'right'  # or 'left', 'below'
)

bins would only apply to the sorting type, similar to how row only applies to matrix questions.

For storage, ranking can be saved in the final order as a pipe-joined string in one column (like mc_multiple does), and sorting saves one column per bin (albums_sorted_love_it, etc.), following the matrix {id}_{row} naming. But open to other formats.

Implementation wise, the registry in R/question_types.R seems like it makes this pretty clean: two new render/restore entries, the new args threaded through sd_question(), and a JS file for the drag and drop behavior registered in the lua filter.

Happy to have any discussion for this feature. If this sounds good, I'll start on it.

[jhelvy]

Thanks @Sunilshah-7, this is great, and I agree with the API in general. As for steps to implement it, I'd suggest forking the repo and making a new branch to work on, then submitting a PR when done and we can review it.

As for the implementation plan, I would suggest starting with a minimal working example of each question type, maybe starting with ranking first as it's simpler. Then once they're both working, we could consider adding other features. For example, as we discussed, we could consider implementing a DOM where when the user clicks on an item to be sorted for the sorting question type, a overlay will pop up, allowing them to more easily sort the item into a bin, which then after sorting would go away and the item would be appropriately sorted. That would allow for a smoother functionality on a smartphone. For the ranking type question, I don't think that's necessary as ranking should already be pretty easy on a phone.