Download button auto clear by any input change - r

Question

I have two input selection and an action button to generate a plot and download the data. I would like to clear the output contents (plot and download button) any time there is a change in the input selection. The code below will only clear the plot and not the download button. Not sure if the reactiveValuesunder the downloadhandleris correct.
library(shiny)
library(ggplot2)
library(openxlsx)
ui = fluidPage(
textInput("textT", label = "Title", value = ""),
textInput("textX", label = "X-Axis Label", value = ""),
actionButton("Btn", "Run", icon=icon("play-circle")),
plotOutput('plot1'),
conditionalPanel(condition = "input.Btn>0", downloadButton("dwload", "Download"))
)
server = function(input, output, session) {
v <- reactiveValues(clearAll = TRUE)
observeEvent(c(input$textT, input$textX), {
v$clearAll <- TRUE
}, priority = 10)
observeEvent(input$Btn, {
output$plot1 = renderPlot({
if (v$clearAll)
return()
else
ggplot(mtcars, aes(x= gear, y= carb)) + geom_line() +ggtitle(input$textT) + xlab(input$textX)
})
output$dwload <- downloadHandler(
filename = function() {
paste0("Checks-", gsub(" ", "_", gsub(":", ".", Sys.time())), ".xlsx")
},
content = function(file) {
if (v$clearAll)
return()
else
quick_xlsx(mtcars, file=file)
}
)
v$clearAll <- FALSE
}, priority = 10)
}
shinyApp(ui, server)
I'd appreciate any help.
Thank you!

Answer 1

Here is a solution using renderUI and req:
library(shiny)
library(ggplot2)
library(openxlsx)
ui <- fluidPage(
textInput("textT", label = "Title", value = ""),
textInput("textX", label = "X-Axis Label", value = ""),
actionButton("Btn", "Run", icon=icon("play-circle")),
uiOutput("widgets")
)
server <- function(input, output, session) {
hideAll <- reactiveVal(TRUE)
observeEvent(list(input$textT, input$textX), {
hideAll(TRUE)
})
observeEvent(input$Btn, {
req(input$textT)
req(input$textX)
hideAll(FALSE)
})
output$plot1 <- renderPlot({
ggplot(mtcars, aes(x= gear, y= carb)) + geom_line() +
ggtitle(input$textT) + xlab(input$textX)
})
output$dwload <- downloadHandler(
filename = function() {
paste0("Checks-", gsub(" ", "_", gsub(":", ".", Sys.time())), ".xlsx")
},
content = function(file) {
quick_xlsx(mtcars, file=file)
}
)
output$widgets <- renderUI({
req(!hideAll())
tagList(
plotOutput('plot1'),
downloadButton("dwload", "Download")
)
})
}
shinyApp(ui, server)