Update dropdown values in R shiny dynamically

Question

I am trying to update values in a dropdown for a shiny app dynamically. So if value is selected in the dropdown classification it should updates the values in the product family dropdown. What am I missing in the code below. It doenst seem to be pciking any value and takes values from the else condition only.

library(shiny)
library(shinyWidgets)

# Define the UI
ui <- bootstrapPage(
  column(3, uiOutput("class_level")),
  column(3,uiOutput("product"))
)


# Define the server code
server <- function(input, output) {

  output$class_level <- renderUI({
    selectInput(
      "selected_class",
      label = h4("Classification Level"),
      choices = list(
        "Brand" = "Brand",
        "Brand1" = "Brand1",
        "Brand2" = "Brand2"
      ),
      selected = "Brand"
    )
  })


  getFlavor <- reactive({

    if (input$selected_class =="Brand") {
      c( "a " = "a",
         "b" = "b",
         "c" = "c"
        )
    }
    else if  (input$selected_class =="Brand1")
    {
      c(
        "1" = "1",
        "2" = "2",
        "3" = "3"
      )
    }
    else   (input$selected_class =="Brand2")
    {
      c(
        "x" = "x",
        "y" = "y",
        "z" = "z"
      )
    }

  })

  output$product <- renderUI({
    pickerInput(
      "selected_product",
      label = h4("Product Family"),
      choices = as.list(getFlavor()),
      selected = as.list(getFlavor()),
      options = list(
        `deselect-all-text` = "None",
        `select-all-text` = "Total",
        `actions-box` = TRUE
      ),
      multiple = F,
      width = "100%"
    )
  })
}

# Return a Shiny app object
shinyApp(ui = ui, server = server)

Robert Tan · Accepted Answer · 2018-07-23 20:52:56Z

You need to return the content within your if statements. You can do this using return

library(shiny)
library(shinyWidgets)

# Define the UI
ui <- bootstrapPage(
  column(3, uiOutput("class_level")),
  column(3,uiOutput("product"))
)


# Define the server code
server <- function(input, output) {

  output$class_level <- renderUI({
    selectInput(
      "selected_class",
      label = h4("Classification Level"),
      choices = list(
        "Brand" = "Brand",
        "Brand1" = "Brand1",
        "Brand2" = "Brand2"
      ),
      selected = "Brand"
    )
  })


  getFlavor <- reactive({

    if (input$selected_class =="Brand") {
      return(c( "a " = "a",
         "b" = "b",
         "c" = "c"
        ))
    }
    else if  (input$selected_class =="Brand1")
    {
      return(c(
        "1" = "1",
        "2" = "2",
        "3" = "3"
      ))
    }
    else   (input$selected_class =="Brand2")
    {
      return(
      c(
        "x" = "x",
        "y" = "y",
        "z" = "z"
      ))
    }

  })

  output$product <- renderUI({
    pickerInput(
      "selected_product",
      label = h4("Product Family"),
      choices = as.list(getFlavor()),
      selected = as.list(getFlavor()),
      options = list(
        `deselect-all-text` = "None",
        `select-all-text` = "Total",
        `actions-box` = TRUE
      ),
      multiple = F,
      width = "100%"
    )
  })
}

# Return a Shiny app object
shinyApp(ui = ui, server = server)

ozanstats · Accepted Answer · 2018-07-23 21:15:57Z

Your approach is somewhat complicated and updatePickerInput would make your job way easier. Here is one possible implementation:

library(shiny)
library(shinyWidgets)

ui <- bootstrapPage(

  column(
    width = 3, 
    selectInput(
      inputId = "selected_class",
      label = h4("Classification Level"),
      choices = c("Brand", "Brand1", "Brand2"),
      selected = "Brand"
    )
  ),
  column(
    width = 3, 
    pickerInput(
      inputId = "selected_product",
      label = h4("Product Family"),
      choices = c("a", "b", "c"),
      options = list(
        `deselect-all-text` = "None",
        `select-all-text` = "Total",
        `actions-box` = TRUE
      ),
      width = "100%"
    )
  )
)

server <- function(input, output, session) {

  observeEvent(input$selected_class, {
    if(input$selected_class =="Brand") {
      choices <- c("a", "b", "c")
    } else if(input$selected_class =="Brand1") {
      choices <- c("1", "2", "3")
    } else {
      choices <- c("x", "y", "z")
    }
    updatePickerInput(
      session,
      inputId = "selected_product",
      choices = choices
    )
  })

}

shinyApp(ui = ui, server = server)

Ruutsa · Accepted Answer · 2024-01-15 21:30:47Z

Bit late to the party but if your data can be in a data frame or tibble then this is more streamlined than existing answers and needs no "widgets".

I needed this kind of thing for column value preview. One select input for column names, another providing column values when user selects another column name.

library(shiny)

firstOutputID <- "selCol"
secondOutputID <- "colDat"

shapeID <- "SHAPE_ID"
shapeName <- "NAME"

ui <- bootstrapPage(
  column(
    width = 3, 
    uiOutput(outputId = firstOutputID),
    uiOutput(outputId = secondOutputID)
  )
)

server <- function(input, output, session) {
  firstSelectID <- "comboCol"
  secondSelectID <- "comboDat"
  
  sampleDF <-
    data.frame(
      col1 = c(1, 2),
      col2 = c("Name 1", "Name 2")
    )
  colnames(sampleDF) <- c(shapeID, shapeName)

  output[[firstOutputID]] <- renderUI({
    selectInput(
      inputId = firstSelectID,
      label = "Column name",
      choices = colnames(sampleDF),
      selected = shapeName
    )
  })
  
  output[[secondOutputID]] <- renderUI({
    # or your own filtering mechanism here:
    filteredChoices <- sampleDF[ , input[[firstSelectID]]]
    
    selectInput(
      inputId = secondSelectID,
      label = "Column data",
      selectize = FALSE,
      size = 5,
      choices = filteredChoices
    )
  })
}

shinyApp(ui = ui, server = server)

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