Validate that a user made a selection

Recall from the video that though it is often good practice to select a default value for your selector inputs, if one should be excluded, you can throw a custom error message to your users that clues them in on what they need to do for the app to run successfully.

We saw in the last exercise that, without a default value for the pickerInput(), the plot is simply blank. Instead of a blank plot, in this exercise you'll show users a custom error message telling them to make the correct selection needed to get the app working.

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Building Web Applications with Shiny in R

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Anleitung zur Übung

Add a custom error message that will display by default letting users know they should select an input for mental versus physical health.

Interaktive Übung

Versuche dich an dieser Übung, indem du diesen Beispielcode vervollständigst.

ui <- fluidPage(
  titlePanel("2014 Mental Health in Tech Survey"),
  sidebarPanel(
    sliderTextInput(
      inputId = "work_interfere",
      label = "If you have a mental health condition, do you feel that it interferes with your work?", 
      grid = TRUE,
      force_edges = TRUE,
      choices = c("Never", "Rarely", "Sometimes", "Often")
    ),
    checkboxGroupInput(
      inputId = "mental_health_consequence",
      label = "Do you think that discussing a mental health issue with your employer would have negative consequences?", 
      choices = c("Maybe", "Yes", "No"),
      selected = "Maybe"
    ),
    pickerInput(
      inputId = "mental_vs_physical",
      label = "Do you feel that your employer takes mental health as seriously as physical health?", 
      choices = c("Don't Know", "No", "Yes"),
      multiple = TRUE
    )    
  ),
  mainPanel(
    plotOutput("age")  
  )
)

server <- function(input, output, session) {
  output$age <- renderPlot({
    # MODIFY CODE BELOW: Add validation that user selected a 3rd input
    
    
    
    
    
    

    mental_health_survey %>%
      filter(
        work_interfere == input$work_interfere,
        mental_health_consequence %in% input$mental_health_consequence,
        mental_vs_physical %in% input$mental_vs_physical
      ) %>%
      ggplot(aes(Age)) +
      geom_histogram()
  })
}

shinyApp(ui, server)

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