Deployment Issue: Filter UI Not Updating Correctly on Shinyapps.io

shiny
,
1

I am currently working on a project on a search engine for all English-taught undergraduate programs in Europe. This will benefit many students, who are looking for alternatives to the costly college programs in the US.

I’m encountering an issue with my Shiny app deployment where UI filters (selectizeInputs for Country/Type/Subject/University) work perfectly locally but behave inconsistently on Shinyapps.io. Specifically:

  • Problem: When selecting a country, the "Subject" and "University" dropdowns only show "All" until a "University Type" is selected. This does not occur in my local R environment.

Code:
(Search Engine - Google Drive)

Request: Can anyone help investigate whether this is caused by environment-specific factors (e.g., package versions, file permissions, or reactive timing differences on Shinyapps.io)?

Thank you for your assistance. Let me know if you need additional details.

Best regards,

2

In lines 87 and 88 of server.R, reacting to a change to the country input, you initialize the subject and university filters to just "All". In lines 109 and 114, reacting to a change in either country or type input, you give the subject filter a bunch of choices and again limit the university filter to "All". In line 132, reacting to a change in any of the country, type or subject inputs, you give the university filter a bunch of choices.

What I don't see is how you know the order in which these event observers will be called. In particular, you have three separate observers triggered by a change to the country input. If the one on line 175 happens to be called third rather than first, it will revert both subject and university filters to just "All". You might try restructuring your code so that each input is watched by just one event observer.

1 Like
3

Thank you! Just fixed it!