R Shiny selectInput that is dependent on another selectInput

Question

I have some data below that I\'m using to create a donut chart in R shiny, where date is a character. I want to be able to select the email whose score I want to vi

Answer 1

You can't access inputs in the ui.R part of the app so you need to use renderUi/uiOutput to dynamically generate your selectInput.

In your ui.R you could add:

uiOutput("secondSelection")

and in your server.R:

 output$secondSelection <- renderUI({
                selectInput("User", "Date:", choices = as.character(dat5[dat5$email==input$Select,"date"]))
        })

Answer 2

You can also do it whout changing ui.R. At least that solution works in an App that I did. Ading this to server.R should have the same effect.

observe({
      updateSelectInput(session, "User", choices = as.character(dat5[dat5$email==input$Select, date]))
})

Though it is a useful and powerful too, I find it "cleaner" te get by without renderUI. It keeps the UI in the UI and the server in the server. But that is just a matter of taste, I suppose.