Shiny/R: Hide error message when no value in selectizeInput

Question

I have a question about shiny app. When there is no value select in numeric input and selectizeInput, my shiny app will show an error because of the empty data frame. I would like to hide the error message if user haven't select their input yet. I know if return will help but it seems not working in this app.

server.r:

library(shiny)

# Define server logic required to draw a histogram
shinyServer(function(input, output) {

result<-reactive({
  if(is.null(input$wt)||is.null(input$hdcount)||is.null(input$season)||is.null(inp ut$gender) )return(NULL)

 mod1<-lm(deathLog ~ InHdCnt+ log(InHdCnt) + season+ SexCode+ AvgArrivWt,  data=mydata)
 newdata = data.frame(AvgArrivWt=input$wt,InHdCnt=input$hdcount,SexCode=input$gender,season=input$season)
data<-predict(mod1, newdata, interval="predict",level=(input$slider1)*0.01 ) 
data

})

output$distPlot <- renderPrint({

result()
})

})

ui.r:

library(shiny)

# Define UI for application that draws a histogram
shinyUI(fluidPage(

# Application title
titlePanel("Death Loss Estimator with On Arrival Factors"),

# Sidebar with a slider input for number of bins 
sidebarLayout(
sidebarPanel(
   numericInput("wt", label = h4("Average Arrival Weight  input"),value="NULL"),
   numericInput("hdcount", label = h4("Arrival Head Count input"),value="NULL"),
   selectizeInput(
     'season', h4('Arrival Season'), choices = c("spring", "summer","fall", "winter"),
     options = list(
       placeholder = 'Please select a season below',
       onInitialize = I('function() { this.setValue(""); }')
     )
   ),
   selectizeInput(
     'gender', h4('Arrival Sex'), choices = c("HOL", "FEM","MAL", "MIX"),
     options = list(
       placeholder = 'Please select a season below',
       onInitialize = I('function() { this.setValue(""); }')
     )
   ),
   sliderInput("slider1", label = h4("Confidence Interval Level"), min = 50, 
               max = 100, value = 80)
   ),

  # Show a plot of the generated distribution
  mainPanel(
   textOutput("distPlot")
  )
  )
 ))

Thanks!

`data=mydata` doesn't help. could you please edit the post and make the code reproducible — Imran Ali, Feb 13 '17 at 18:28
Thanks all! The `validate()` function will solve this problem. Still many thanks for all of replies! — Joanna, Feb 13 '17 at 19:17

score 18 · Accepted Answer · answered Feb 13 '17 at 19:12

I would recommend using validate and need. You can put this at the top of your reactive expression:

validate(
   need(input$wt, "Please select a weight"),
   need(input$hdcount, "Please select a head count")
)

Alternatively you can use req:

req(input$wt)
req(input$hdcount)

Shiny/R: Hide error message when no value in selectizeInput

1 Answers1