Shiny reactivity with IncludeMarkdown?

Question

Trying to take these ideas a step further:

• HTML/Text/Markdown in Shiny
• Render Images

I want to include a reactive markdown file ( *.Md ) in a mainPanel conditional on the input to a selectInput . How do I do it?

I've tried variations on renderText , renderPrint and using eval inside includeMarkdown . Nothing seems to work so far.

EG.

### ui.R

shinyUI(fluidPage(    
  sidebarLayout(
    sidebarPanel(
      selectInput("var1",
                  label= "Please Select option",
                  choices= c("option1", "option2", "option3"),
                  selected= "option1"
    ),

    mainPanel(
      h3("guide:")
      includeMarkdown("md_file")
    )
  )
))

### server.R
shinyServer(function(input, output) {

   output$md_file <- 
     if (input$var1 == "option1") {
       renderPrint({"option1.Md"})
     } else if (input$var1 == "option2") {
       renderPrint({"option2.Md"})
     } (input$var1 == "option3") {
       renderPrint({"option3.Md"})
     }
   })
})


R> shiny::runApp('C:/Shiny_demo')

Listening on http://127.0.0.1:6421
Warning in readLines(con) :
cannot open file 'md_file': No such file or directory
Error in readLines(con) : cannot open the connection

Answer 1

Based on a discussion with Joe Cheng in the Shiny Google group, the answer is:

In your UI:

uiOutput("md_file")

In your server:

output$md_file <- renderUI({
  file <- switch(input$var1,
    option1 = "option1.Md",
    option2 = "option2.Md",
    option2 = "option3.Md",
    stop("Unknown option")
  )
  includeMarkdown(file)
})

Thanks, Joe!