updateSelectInput is overwritten by a selectInput in a shiny app

Question

In the example below the action button would update the select input values. However, the second selection input is dependent on the first one and when the action button is selected the update to "virginica" does not occur.

ui <- fluidPage(

        actionButton(inputId = "action", label = "click"),
        uiOutput("select_col"),
        uiOutput("select_species")
    
    )
    
    #
    server <- function(input, output) {
    
    output$select_col <- renderUI({
        selectInput(inputId = "select_col", 
                label = "select_col", 
                choices = colnames(iris))
    })
    
    output$select_species <- renderUI({
        selectInput(inputId = "select_species",
                label = "Species",
                choices = unique(iris[ ,input$select_col]))
    })
    
    observeEvent(input$action, {
        updateSelectInput(inputId = "select_col", selected = "Species")
        updateSelectInput(inputId = "select_species", selected = "virginica")
    })
    
    }
    
    # Run the application 
    shinyApp(ui = ui, server = server)

I expect the following result: 'Species'in selectinput 'select_col' and setosa in selectinput 'Species'

Thanks @StéphaneLaurent, I fixed it, but I still need to double click on action button to have the expected result. — Vander Souza, Feb 14 '23 at 13:49
Ah I see the problem now. I would include a second observer: `observeEvent(input$select_col, { # second update input here })`. — Stéphane Laurent, Feb 14 '23 at 13:54
@StéphaneLaurent, this is the best solution so far, but it will trigger the update without the user clicking the button. — Vander Souza, Feb 14 '23 at 16:01

Stéphane Laurent · Accepted Answer · 2023-02-18T14:01:29.693

0

That should work:

  xxx <- reactiveVal(NULL)
  
  observeEvent(input$action, {
    updateSelectInput(inputId = "select_col", selected = "Species")
    xxx(TRUE)
  })
  
  observeEvent(xxx(), {
    updateSelectInput(inputId = "select_species", selected = "virginica")
    xxx(NULL)
  })

EDIT

No that doesn't work. Here is a solution using the delay function of the shinyjs package:

  observeEvent(input$action, {
    updateSelectInput(inputId = "select_col", selected = "Species")
    delay(0, updateSelectInput(inputId = "select_species", selected = "virginica"))
  })

Don't forget:

library(shiny)
library(shinyjs)

ui <- fluidPage(
  useShinyjs(), # <- don't forget that
  actionButton(inputId = "action", label = "click"),
  ......

edited Feb 18 '23 at 14:01

answered Feb 14 '23 at 17:21

Stéphane Laurent

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Hi @StéphaneLaurent, it didn't work. – Vander Souza Feb 18 '23 at 12:23
@VanderSouza I see: there's a delay caused by the `renderUI`. Observe that it works if you click two times. Let me think more about this problem. – Stéphane Laurent Feb 18 '23 at 13:57

updateSelectInput is overwritten by a selectInput in a shiny app

1 Answers1

EDIT