Shiny - conditional panel not recognizing input - r

Question

I'm working with shiny and I'm having difficulty having R recognize input when using conditionalPanel. I have two such panels in my app because I need them to produce a certain list depending on which of the radio buttons a user selects.
Everything is rendered fine from the UI perspective, but for some reason R is unable to pick up any input when the 'Name' option is passed through the conditional panel, even if an item is entered in the field. The correct list is used, but for some reason it doesn't detect any input. Here's a screenshot of the selections and results.
I have no issues if I choose the other option from within the radio buttons and enter an item--it works as expected. Here's the code I'm working with.
ui <- fluidPage(
sidebarPanel(
# the user can choose from two options within the radio buttons
radioButtons("items_type", label = "Choose items for analysis"
, choices = list("Items - Item number & name" = "Both", "Items - Item name only" = "Name")
, selected = "Both")
# if the 'Both' option is selected, the items_list_names_id option is used
, conditionalPanel(
condition = "output.items_type == 'Both'"
, selectInput("items", label = NULL, choices = items_list_names_id, multiple = TRUE))
# if the 'Name' option is selected, the items_list_names option is used. input
# is not being detected here for some reason, and I'm wondering if it's because
# I use "items" for both selectInputs
, conditionalPanel(
condition = "output.items_type == 'Name'"
, selectInput("items", label = NULL, choices = items_list_names, multiple = TRUE))
# action button so the user can submit for analysis based on their selected options
, actionButton("go", "Run", style = "color: white; background-color: #2759aa")
)
)
server <- function(input, output){
# this portion is used to detect if the user alternates between either option from the radio buttons and uses the appropriate selectInput option
output$items_type <- reactive({
input$items_type
})
outputOptions(output, "items_type", suspendWhenHidden = FALSE)
Results <- eventReactive(input$go, {
# this portion is simply for testing for me to see how R recognizes the inputs
observe({print(input$items_type)})
observe({print(input$items)})
# checks to make sure the user selects at least 1 item. For some reason,
# this portion is triggered when at least 1 item is selected under the 'Name'
# condition from the conditional panel.
validate(
need(input$items > 0, 'Please select at least 1 item for analysis')
)
#other steps start here, but the above is the more pertinent part
}
EDIT: So it looks like having the same input id for both selectInput options is what's causing R to not recognize the input when it switches between the conditional panels. However, it would be ideal to have one input id because intput$item is used in other portions of my code not shown above. Rewriting the code so that it would use two variables, input$item1 and input$item2 for example, for each condition would be potentially very troublesome. I'm open to any suggestions to avoid this.
EDIT 2: I was thinking maybe using a single conditonalPanel and using a switch statement to alternate between the two lists depending on the user's selection. This should work, theoretically, and would be a convenient solution without modifying all of my other code. It looks like this:
, conditionalPanel(
condition = "output.items_list_selection"
, selectInput("items", label = 'Select items'
, choices = switch("output.items_list_selection", "Both" = items_list_names_id, "Name" = items_list_names)
, multiple = TRUE))
But a drop down menu doesn't appear as it's supposed to with this revision.

Answer 1

A possible solution is to use updateSelectInput , so there is no problem with two id having the samedi inputId
library(shiny)
items_list_names_id = c("id1", "id2")
items_list_names = c('name1', 'name2')
ui <- fluidPage(
sidebarPanel(
# the user can choose from two options within the radio buttons
radioButtons("items_type", label = "Choose items for analysis"
, choices = list("Items - Item number & name" = "Both", "Items - Item name only" = "Name")
, selected = "Both"),
# if the 'Both' option is selected, the items_list_names_id option is used
selectInput("items", label = NULL, choices = c('init'), multiple = TRUE),
# action button so the user can submit for analysis based on their selected options
actionButton("go", "Run", style = "color: white; background-color: #2759aa")
)
)
server <- function(input, output, session){
# change the choices depending on the value of input$intems_type
observeEvent(input$items_type, {
if(input$items_type == 'Both'){
updateSelectInput(session, 'items', label = NULL, choices = items_list_names)
}
if(input$items_type == 'Name'){
updateSelectInput(session, 'items', label = NULL, choices = items_list_names_id)
}
})
# check if it's working
observeEvent(input$go,{
print(input$items)
print(input$items_type)
})
}
shinyApp(ui, server)