Can `cleave()` play nicely with shiny's `validate(need(...))`?

[jonmcalder]

Thanks for this really nice package @JohnCoene! Simple, yet powerful & effective.

The below app example behaves as expected if cleave() is commented out in the server function, but with cleave() included, the error "state" A regrettable decision is never revealed in the #thing output, and instead only the other 2 output "states" Required input is required 😂 and Good choice are realisable, or both are visible at the same time (when the error state is to be expected).

Is it possible to get cleave() & validate(need(...)) to work together?

library(shiny)
library(sever)

ui <- fluidPage(
  use_sever(),
  fluidRow(
    selectInput("required_input", "Required input",
      choices = c("Red pill", "Blue pill"), 
      multiple = TRUE
    ),
    uiOutput("thing")
  )
)

server <- function(input, output){
  cleave()
  
  # will generate errors
  output$thing <- renderUI({
    validate(need(input$required_input, "Required input is required 😂"))
    if("Red pill" %in% input$required_input) {
      h1("Good choice!")
    } else {
      stop("A regrettable decision.")
    }
  })
  
}

shinyApp(ui, server)

Shiny applications not supported in static R Markdown documents

^{Created on 2020-07-23 by the reprex package (v0.3.0)}

Session info

devtools::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
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#>  version  R version 4.0.2 (2020-06-22)
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#>  language (EN)                        
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#>  date     2020-07-23                  
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[JohnCoene]

Hi Jon,

Thank you very much!

I'm afraid that had nothing to do with validate or need, it was buggy regardless 😄

I just pushed a fix. The issue it correctly removes the "cleave" when a new value is set and hides everything underneath error messages on an error. This should make it a lot more robust!

Thanks again for reporting this! Let me know if this does not actually fix it.

[jonmcalder]

Thanks for the quick response.

That does fix the underlying bug (with "old output" remaining visible instead of being hidden when an error state arises) so that's a definite improvement 🎉

However, it doesn't fully address the issue I was raising, which is that ideally I'd like to be able to have validate() deal with the predictable error states (e.g. those caused by user error or omission such as missing input values), and have cleave() deal with other errors that may surface later while processing a reactive or output.

Keeping with my example app above, this means that the error message A regrettable decision. is never shown, and instead the validate(need(...)) message is shown for any error.

Put another way - when "Blue pill" is selected (on it's own), then I'd expect to see the A regrettable decision. error message, but instead I see the message defined in validate(need(...))

[JohnCoene]

Aaaaah, yes indeed, sorry!

I think this time I have it haha. Shiny raises those as "silent errors" javascript-side. I have added an argument to the cleave function that allows controlling whether you want to cleave those or not. It defaults to FALSE = the behaviour you want.

Let me know if this this what you were after, I would not be surprised I misunderstood again haha

[jonmcalder]

Excellent! You nailed it 👍

And yes, I think that's a good default - assuming that I'm not alone in having relied heavily on validate() before venturing into the use of {sever} & cleave().

Sorry for not trying to diagnose further or attempt a PR - my javascript ability is too limited at this stage and I had no idea how shiny handled validation errors on the javascript side of things.

When raising the issue I did wonder whether maybe I was just wrong to assume these could be used together and should instead just be cleaving all errors (cos that could might be a reasonable approach for some apps), but I do think they are more powerful when used together - allowing for "validating" of expected errors and "cleaving" of unexpected errors.