shiny 中带有 verbatimTextOutput 的参数类型无效

Question

I am having a very difficult time getting to understand how Shiny modules work. I am building an app using a Golem template ( https://github.com/ThinkR-open/golem ).

Edit I realized that my error was not tied to any modules, so generated a minimal example. To review the old code, look in the edit history

library(shiny)

app_ui <- function() {
  fluidPage(
    textInput(inputId = "test", label = "Labley", value = "val"),
    verbatimTextOutput(outputId = "out", placeholder = "None")
  )
}

app_server <- function(input, output, session) {
  output$out <- renderText(expr = input$test)
}

shinyApp(ui = app_ui, server = app_server)

This causes:

Error in !: invalid argument type

How do I get UI to print my text input?

Answer 1

@KasperThystrupKarstensen the problem here is, that verbatimTextOutput 's placeholder argument requires a boolean input (see usage in ?verbatimTextOutput ). However, you passed a string.

This works:

library(shiny)

app_ui <- fluidPage(
  textInput(
    inputId = "test",
    label = "Labley",
    value = "val"
  ),
  verbatimTextOutput(outputId = "out", placeholder = FALSE)
)

app_server <- function(input, output, session) {
  output$out <- renderText(expr = input$test)
}

shinyApp(ui = app_ui, server = app_server)

?verbatimTextOutput :

placeholder: if the output is empty or NULL, should an empty rectangle be displayed to serve as a placeholder? (does not affect behavior when the the output in nonempty)