Use box in shiny folder structure.

[shahronak47]

I have a shiny app and this is my folder structure.

- Parent_Folder
    - Code
         - ui.R
         - server.R
    - Data
         - data.rds
    - app.R

Where ui.R looks like

box::use(bslib[page_fluid, layout_columns], 
         shiny[uiOutput])

#' @export
ui <- page_fluid(
  title = "Dashboard", 
  layout_columns(
    fill = FALSE,
    ......
    ......
  )
)

and server.R is a function

box::use(shiny[renderUI])

#' @export
server <- function(input, output, session) {
  out <- readRDS("Data/data.rds")  
  .......
  .......
}

In app.R I am calling this as

box::use(code/ui, 
         code/server, 
         shiny[shinyApp])

shinyApp(ui$ui, server$server())

and when I click on Run App in Rstudio I get

Error in server$server() : argument "output" is missing, with no default

This is the first time I am trying to use box so ignore any obvious mistakes that I have made.

My questions are -

1. How to make this run? What am I doing wrong?
2. Does this folder structure makes sense? Do you have any recommendations for shiny? I have tried rhino but that is overwhelming for me and I want to keep my shiny project simple.

[klmr]

Hi Ronak,

That error isn’t actually related to ‘box’, it’s just a typo: you are calling the server$server function instead of passing it to shinyApp. Do the following instead:

shinyApp(ui$ui, server$server)

But there are some ‘box’ related code issues as well. In fact, some things might happen to work but aren’t guaranteed to work, and I strongly suggest changing them to make the code more robust.

First off, inside the server you are using the wrong path in readRDS(). You need to specify the path relative to the current module, because otherwise you are relying on the value of getwd(), which isn’t generally robust. Use box::file() to get a guaranteed robust path:

out <- readRDS(box::file("../Data/data.rds"))

Secondly, you are currently importing relative modules via the paths code/ui and code/server, respectively. However, these are actually global module specifications. As a consequence, ‘box’ will initially search for them in the module search path, which is specified via getOption('box.path'). ‘box’ will only fall back to searching these modules locally if it can’t find a matching globally installed module.

To use submodules inside a project, I strongly recommend using relative module path specifications. To do this, prefix the paths with ./. In other words:

box::use(./code/ui,
         ./code/server,
         shiny[shinyApp])

And personally I prefer aligning the module specifications:

box::use(
  ./code/ui, 
  ./code/server, 
  shiny[shinyApp],
)

Also, make sure the capitalisation of the folder names matches, otherwise the code might work on Windows but will fail on other systems (your directory tree uses Code/, but your code uses code/).

[shahronak47]

Oops! That was embarrassing. Nonetheless thank you for providing me other tips as well. Those are really helpful.