formatCurrency in DT::renderDataTable when datatable has no columns

Question

I'm using renderDataTable in my shiny app to display the contents of a data.table vals$content4table which is a reactiveValues.

It can happen that the vals$content4table is equal to a datatable with no columns. In that case i have an error while using formatCurrency because it searches for a column that does not exist. Is there any way to check if the datatable has columns with ifelse to avoid the error?

Here is a piece of my code of my server.

#initialising vals$content4table when launching the app
 vals <- reactiveValues(content4table = if(someBoolean) {data.table(NULL)} else {data.table("Column1" = "whatever","Currency" = 1000}
  )
 
output$TableInUI <- DT::renderDataTable(datatable(vals$content4table) %>% ifelse(nrow(vals$content4table)>0,formatCurrency(2, currency = "", interval = 3, mark = ",",  digits = 0),fnothing()))

#where fnothing is defined as
fnothing<-function(df) return(df)

The above code doesn't work and gives this error: Warning: Error in ifelse: unused argument (fnothing())

Answer 1

You could use req:

output$TableInUI <- DT::renderDataTable({
   req(isTRUE(ncol(vals$content4table)>0))
   vals$content4table
})