Shiny - conditionalPanel - set condition as output from server - r

Question

I am trying to build an app in shiny that will be able to load a dataset in the server function and then based on the user choose and then if there is a factor variable to open check box using conditionalPanel. is there a way to output variable from the server as the condition of the condtionalPanel?
Here is what I tried:
library(shiny)
library(caret)
ui <- fluidPage(
selectInput('dataset', 'Select Dataset',
list(GermanCredit = "GermanCredit",
cars = "cars")),
conditionalPanel(
condition = "output.factorflag == true",
checkboxInput("UseFactor", "Add Factor Variable")
)
)
server <- function(input, output) {
# Loading the dataset
df <- reactive({
if(input$dataset == "GermanCredit"){
data("GermanCredit")
df <- GermanCredit
}else if(input$dataset == "cars"){
data(cars)
df <- cars
}
return(df)
})
# Loading the variables list
col_type <- reactive({
col_type <- rep(NA,ncol(df()))
for(i in 1:ncol(df())){
col_type[i] <- class(df()[,i])
}
return(col_type)
})
outputOptions(output, "factorflag", suspendWhenHidden = FALSE)
output$factorflag <- reactive({
if("factor" %in% col_type()){
factor.flag <- TRUE
} else {factor.flag <- FALSE}
}
)
}
shinyApp(ui = ui, server = server)
Thank you in advance!

Answer 1

You were almost there, you need to put the outputOptions after the declaration of factorflag. Just reengineered a bit your code:
library(shiny)
library(caret)
ui <- fluidPage(
selectInput('dataset', 'Select Dataset',
list(GermanCredit = "GermanCredit",
cars = "cars")),
conditionalPanel(
condition = "output.factorflag == true",
checkboxInput("UseFactor", "Add Factor Variable")
)
)
server <- function(input, output) {
# Loading the dataset
df <- reactive({
if(input$dataset == "GermanCredit"){
data("GermanCredit")
GermanCredit
}else {
data("cars")
cars
}
})
output$factorflag <- reactive("factor" %in% sapply(df(),class))
outputOptions(output, "factorflag", suspendWhenHidden = FALSE)
}
shinyApp(ui = ui, server = server)