Is it possible to add a "Previous" button?

[durraniu]

Description

Thank you for creating {surveydown}. I was wondering if the following is possible:

• A "Previous" button. I see sd_next(), what about sd_previous()?

[jhelvy]

Hi,

Thanks for trying out surveydown. Since you asked three unrelated questions, I'm going to answer the first one about having a previous button here, and for the other two please make separate posts on those issues so we can keep track of them. They're also important points, but worthy of their own separate discussion thread.

We have discussed whether or not to allow a "previous" button before, e.g., here. One of the challenges is that when you allow a previous button, any page navigation logic that was previously executed needs to be undone. For a simple survey where users are only allowed to go forward or backward by a single page at a time and there is no conditional skipping logic, this is simple and easy to do. However, surveydown allows things like conditional page skipping, where users can be sent to different pages in the survey depending on some condition, such as a response to a question. This makes adding a previous button more complicated. For now, we've avoided it as most users haven't needed it, but it is something we can look into.

At a minimum, we could perhaps allow it and restrict it to only "simple" surveys that don't have any conditional skipping logic. That is easy enough to check for, and we could throw an error if we detect both previous buttons and conditional skipping logic.

The question I have is, how should we implement it?

Right now users insert next buttons by adding sd_next() in code chunks. It feels like it'd get annoying if you had to add both sd_previous() and sd_next() on each page. Perhaps instead we could just have a yaml option, like previous-button: true? If so, then any time sd_next() is called, a previous button will also automatically be added to allow previous buttons to appear?

Another idea is you could potentially override this behavior with sd_next(prev = FALSE) or something, so at the local level if you set prev = TRUE or prev = FALSE you'll get a previous button.

This makes me also think, what if the function was just sd_nav()? Then it could be more generic, and you could control whether you have next / previous buttons as well as their labels and which page they go to?

I'm just brainstorming here. If we do decide to implement a previous button functionality, I'd like to think about different approaches to the UI for how it'll work before we start working on it.

What do you think @pingfan-hu and @Buneabt?

[pingfan-hu]

Yes professor @jhelvy . I agree that we can add a previous button for simple surveys without conditional logic. Here are my thoughts:

1. Create a new function called sd_nav() to specifically handle this (aka sd_nav() generates both Previous and Next buttons).
2. sd_nav() should only work if there is no conditional page skipping, but can tolerate conditional questions and conditional stopping. Hard stop should trigger in R console if violated.
3. Keep sd_next() as it is and no need to add YAML.

This way, we don't need to change any existing logics of sd_next(), nor do we need to add YAML keys, and sd_nav() is the only thing we need to handle. How does it sound?

[jhelvy]

I like sd_nav() as a new function to replace sd_next(). We could set it up so that the default behavior is exactly what you currently get right now with sd_next(): it only inserts a next button with a default label, and it navigates to the immediate next page. We could also then depreciate sd_next(). It could still work if users have it, but it can post a message saying to start using sd_nav().

The main thing I wanted to think about though was what arguments the function should have. Right now sd_next() has an argument to determine the label that's displayed as well as the target page to navigate to. So if a new function sd_nav() is going to take its place, then we're going to need a label and target page argument for both the previous and next buttons. We also need some way of determining whether to have a previous button at all.

Maybe arguments could be:

• label_next
• label_prev
• page_next
• page_prev

If page_prev = NULL is set as the default, then there won't be a previous button by default. Users would have to specify a page_prev value for a previous button to appear.

The only annoying thing with this setup is that users would have to specify the page_prev on every call to sd_nav(), making sure to get the page_prev value correct. If you wanted a survey to have all next and previous buttons to just go to the immediate next and previous page, that should be easier to enable. That's why I was thinking that having some optional key in the yaml would be helpful. It would be nice if there was a way to enable previous buttons for all calls to sd_nav(), which could be overridden by locally set argument values in sd_nav(). I'm not yet sure how best to handle that.

[jhelvy]

This is now handled in v1.0.0