How to get a null value to work with selectInput in Shiny

Question

I'm trying to integrate selectInput with a Null option so that I can filter by an athlete's first year in the NBA, but when I run the app, the graph just won't load. Here's a condensed version of my code:

ui <- fluidPage(
titlePanel(title = h4("NBA StatsR", align = "center")),
tabsetPanel(type = "tabs",
  tabPanel("NBA 2019-2020",
   sidebarLayout(
     sidebarPanel(
       selectInput(inputId = "Draft Class",
                   label = "DraftClass",
                   choices = c("NULL","2007"),
                   selected = NULL)
),
mainPanel(
 plotOutput(outputId = "plot4", width = "104%",
            height = "500px")
     )))))

server <- function(input, output, session) {
  output$plot4 <- renderPlot({
    listVal <- reactive({
      if (is.null(input$DraftClass)){
        "yearSeasonFirst"}
      else {
        input$DraftClass}
    })
    NBA1920withLuka %>%
      filter(minutesPerGame >= 15) %>%
      filter(ratioPER >= 10) %>%
      filter(countGames >= 9) %>%
      filter(yearSeasonFirst == listVal()) %>%
      top_n(10, get(input$select4)) %>%
      ggplot(aes(x = reorder(namePlayer,
                             ptsPerGame),
                 y = ptsPerGame)) +
      geom_bar(stat = "identity")
  })
}

Here's what I get:

With the rest of my code, I get this: How can I fix this?

Solution: It's an open and shut case, Johnson. My selectInput id was "Draft Class", but I referred to it as DraftClass without a space. However, I found that even with other workarounds (as those suggested here and in other places), they would just not output anything where the filter(yearSeasonFirst == yearSeasonFirst) So I tried an if else, where if input$DraftClass == the null option I wanted, run the output code without the filter for yearSeasonFirst

Answer 1

I can't fully test this without the NBA1920withLuka data frame, but replacing NULL with a string should work:

ui <- fluidPage(
  titlePanel(title = h4("NBA StatsR", align = "center")),
  tabsetPanel(type = "tabs",
              tabPanel("NBA 2019-2020",
                       sidebarLayout(
                         sidebarPanel(
                           selectInput(inputId = "Draft Class",
                                       label = "DraftClass",
                                       choices = c("[first season]", "2007"),
                                       selected = "[first season]")
                         ),
                         mainPanel(
                           plotOutput(outputId = "plot4", width = "104%",
                                      height = "500px")
                         )))))

server <- function(input, output, session) {
  listVal <- reactive({
    if (input$DraftClass == "[first season]"){
      "yearSeasonFirst"}
    else {
      input$DraftClass}
  })
  output$plot4 <- renderPlot({
    NBA1920withLuka %>%
      filter(minutesPerGame >= 15) %>%
      filter(ratioPER >= 10) %>%
      filter(countGames >= 9) %>%
      filter(yearSeasonFirst == listVal()) %>%
      top_n(10, get(input$select4)) %>%
      ggplot(aes(x = reorder(namePlayer,
                             ptsPerGame),
                 y = ptsPerGame)) +
      geom_bar(stat = "identity")
  })
}

(Also moved the reactive list outside renderPlot , as noted by @SmokeyShakers.)