Execute an expression safely in server
Execute an expression without generating an error, instead display the error to the user in an alert.
execute_safely( expr, title = "Error", message = "An error occured, detail below:", include_error = TRUE, error_return = NULL, session = shiny::getDefaultReactiveDomain() )
expr |
Expression to evaluate |
title |
Title to display in the alert in case of error. |
message |
Message to display below title. |
include_error |
Include the error message generated by R. |
error_return |
Value to return in case of error. |
session |
Shiny session. |
Result of expr if no error, otherwise the value of
error_return (NULL by default to use req
in other reactive context).
library(shiny)
library(shinyWidgets)
ui <- fluidPage(
tags$h2("Execute code safely in server"),
fileInput(
inputId = "file",
label = "Try to import something else than a text file (Excel for example)"
),
verbatimTextOutput(outputId = "file_value")
)
server <- function(input, output, session) {
options(warn = 2) # turns warnings into errors
onStop(function() {
options(warn = 0)
})
r <- reactive({
req(input$file)
execute_safely(
read.csv(input$file$datapath)
)
})
output$file_value <- renderPrint({
head(r())
})
}
if (interactive())
shinyApp(ui, server)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.