Shiny numericInput() does not respect min and max values

Question

In Shiny, if I have a numericInput as an input, when the user manually enters a value, it is not recognizing or respecting the max/min value and allows any number.If the user selects an arrow for the dropdown it respects the values but just not when entered manually. How can I have the manual entry respect the upper/lower value bounds?

numericInput("test", label=("TestLabel"), min=0, max=10, value="", step = 1.0),

Answer 1

As @HubertL pointed out it is a reported bug.

So you have two possibilities:

1. Accept a small work around, see below or
2. Wait for it to be fixed

In case an ugly work around is useful for you until it is fixed:

library(shiny)

ui <- fluidPage(
  uiOutput("numInput"),
  textOutput("text")
)

server <- function(input, output) {
  global <- reactiveValues(numVal = 25, numMin = 1, numMax = 100)

  numVal <- reactive({
    if(!is.null(input$num)){
      if(input$num < global$numMin) return(global$numMin)
      if(input$num > global$numMax) return(global$numMax)     
      return(input$num)
    }else{
      return(global$numVal)
    }
  })

  output$numInput <- renderUI(numericInput("num", "", min = global$numMin, 
                              max = global$numMax, value = numVal()))

  output$text <- renderText(input$num)
}

shinyApp(ui, server)

Downside is that you cant change values as fast with the up/down "arrows".

Edit: Request to generalize the answer for multiple inputs:

library(shiny)
amtInputs <- 6

ui <- fluidPage(uiOutput("numInput"))

server <- function(input, output) {
  global <- reactiveValues(numVal = rep(25, amtInputs), numMin = rep(1, amtInputs), 
          numMax = rep(100, amtInputs))

  numVal <- reactive({
    out <- rep(0, amtInputs)
    for(idNr in 1:amtInputs){
      id <- paste0("num", idNr)      
      if(!is.null(input[[id]])){
        out[idNr] <- input[[id]]
        if(input[[id]] < global$numMin[idNr]) out[idNr] <- global$numMin[idNr]
        if(input[[id]] > global$numMax[idNr]) out[idNr] <- global$numMax[idNr]
      }else{
        out[idNr] <- global$numVal[idNr]
      }
    }
    return(out)
  })

  output$numInput <- renderUI({
    inputs <- tagList()
    for(idNr in 1:amtInputs){
      inputs <- tagList(inputs, numericInput(paste0("num", idNr), "", 
 min = global$numMin[idNr], max = global$numMax[idNr], value = numVal()[idNr]))
    }
    return(inputs)
  })
}
shinyApp(ui, server)

Answer 2

After so many years, this problem has not been fixed in Shiny. The workaround seems complicated. There is also a shinyvalidate package being proposed as a solution, but it does not enforce a upper or lower limit.

One alternative solution I found is to use JavaScript code to customize the behavior and enforce a limit. In the example below, a numericInput must be bigger than 1. If the user enters a value that is smaller than 1, a warning message is shown and the value is set to 1.5 after 2 seconds.

library(shiny)

ui <- fluidPage(
  tags$head(
    tags$script(HTML("
            $(document).on('shiny:connected', function(event) {
                $('#limma_fc').on('input', function() {
                    var inputElement = $(this);
                    setTimeout(function() {
                        var value = parseFloat(inputElement.val());
                        if (value < 1) {
                            inputElement.val('1.5');
                            alert('Must be greater than 1');
                            inputElement.trigger('change'); // trigger update
                        }
                    }, 2000); // Wait for 2 seconds
                });
            });
        "))
  ),
  numericInput("limma_fc", "Limma FC:", value = 1.5, min = 1, max = 100, step = 0.5),
  verbatimTextOutput("value")
)

server <- function(input, output, session) {
  output$value <- renderText({
    paste("Current value:", input$limma_fc)
  })
}

shinyApp(ui, server)