Depending on a Shiny ui input, a selection list is to be chosen which is used for the following input

[Wilczewski]

I need to calculate in ui a selection list that is dependent on an input. I have not found a solution on stackoverflow or google yet. Maybe someone can give me a solution suggestion. Code example:

fluidRow(
box(width = 2,
selectInput(
"Methode_A",
label = "Methode",
choices = c("1","2","3"),
multiple = TRUE
)
),

#Pseudocode

if(Methode_A=="1"){list_a<-.... code 1 }

if(Methode_A=="2"){list_a<-.... code 2 }

box(width = 2,
selectInput(
"Linie_A",
label = "Linie",
choices = list_a,
multiple = TRUE
)
)

I hope someone has an inspiration.

[scottyd22]

One way this can be accomplished is by creating an observeEvent() in the server that updates the second input based on the selection in the first. Below is a simple app that illustrates what this might look like. Both inputs are created in the ui section. I set multiple to FALSE in the first input (Methode_A) to limit the number of associated if() statements in the observeEvent(). However, you can define list_a for multiple selections if desired.

library(shiny)

ui <- fluidPage(
  fluidRow(
    selectInput("Methode_A",
                label = "Methode",
                choices = c('', "1","2","3"),
                selected = '',
                multiple = FALSE
                ),
    selectInput("Linie_A",
                label = "Linie",
                choices = '',
                multiple = TRUE
                )
    )
  )

server <- function(input, output, session) {
  
  observeEvent(input$Methode_A, {
    list_a = ''
    if(input$Methode_A == '1') {list_a = c('1A', '1B', '1C')}
    if(input$Methode_A == '2') {list_a = c('2A', '2B', '2C')}
    if(input$Methode_A == '3') {list_a = c('3A', '3B', '3C')}
    
    updateSelectInput(session,
                      inputId = 'Linie_A',
                      label = 'Linie',
                      choices = list_a)
  })
}

shinyApp(ui, server)

[Wilczewski]

Hello Scotty, many thanks for the fast solution. It works perfectly.
Now I want to use the method for an update of the dateRangeInput functions. Here I get an error message that I can not interpret. Can you take a look at it?
Here is the code

                box(width = 4,
                    dateRangeInput(inputId = "Datumsbereich_A", #+#
                                   label ="Datum",
                                   language = "de",
                                   startview = "month",
                                   width="100%",
                                   start = Start_Datum,
                                   end = End_Datum,
                                   min = Datum_min_A,
                                   max =Datum_max_A)
                    
                )

Here my observeEvent

observeEvent(input$Berichtszeitraum,{
    updateSelectInput(session, inputId = "Datumsbereich_A", start = "2020-10-01" ,end = "2022-10-01" )
   
  })

I get the following error message:

Warning: Error in updateSelectInput: unused arguments (start = "2020-10-01", end = "2022-10-01")

What does the error message mean?

Best regards
Friedbert

[scottyd22]

It looks like you should be using updateDateRangeInput() instead of updateSelectInput().

[Wilczewski]

Hi Scotty, many thanks for the tip. It works!