Introduction

Sometimes you want to send a message to the user of your shiny app ,

feedback <- function(input, id,  value_lower, value_upper, value_model_lower, value_model_upper, units) {

    if(input<value_lower | input>value_upper) {
      hideFeedback(id)
      showFeedbackDanger(
        inputId = id,
        text = glue('The value entered, {input}, is outside of the range of accepted values')        )
    } else if (input<value_model_lower | input>value_model_upper) {
      hideFeedback(id)
      showFeedbackWarning(
        inputId = id,
        text = glue("This model has been developed for values between {value_model_lower} and {value_model_upper} {units}. The entered value of {input} {units} is outside this range and the result of the calculations will be less reliable.")
      )
    } else {
      hideFeedback(id)
    }

}

observeEvent( input$wt, {  
    req(input$wt)  
    feedback(input$wt, id='wt', value_lower=wt_lower, value_upper = wt_upper, 
             value_model_lower=wt_model_lower, value_model_upper=wt_model_upper, units='kg')
})