R Shiny- Dynamic FileInput label - r

Question

I am building an app where I need to have option for single file upload vs dual file upload. I have achieved single vs dual file upload using conditionalpanel, but I am not being able to change the FileInput label.
This is what I need-
1) When user clicks on single file. There should be only one FileInput with label "Choose Consolidated file"
2) When user clicks on separate files. There should be 2 FileInputs with label "Choose test file" and "Choose control file"
Below is a working code
library(shiny)
ui<-shinyUI(fluidPage(
sidebarLayout(
sidebarPanel(
radioButtons("p", "separate input files or consolidated?",
list("Single file"='a', "Separate files"='b'))
),
mainPanel(
fileInput("file1","Choose first file",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
),
conditionalPanel(
condition = "output.dual",
fileInput("file2", "Choose second file",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
)
),
conditionalPanel(
condition = "output.dual",
checkboxInput('headercheckbox',
"Files have different headers?",
value = FALSE
)
)### bracket close of conditional panel
)
)
))
server<-shinyServer(function(input, output) {
output$dual <- reactive({ input$p == 'b' })
outputOptions(output, 'dual', suspendWhenHidden = FALSE)
})
shinyApp(ui,server)
Let me know if anyone can help?

Answer 1

I recommend using uiOutput and renderUI for this. If you want to know more about these functions the shiny reference materials are pretty good. https://shiny.rstudio.com/reference/shiny/latest/renderUI.html
ui<-shinyUI(
fluidPage(
sidebarLayout(
sidebarPanel(
radioButtons("p", "separate input files or consolidated?",
list("Single file"='a', "Separate files"='b'))
),
mainPanel(
uiOutput('file_area_1'),
uiOutput('file_area_2'),
uiOutput('diff_headers')
)### bracket close of conditional panel
)
)
)
server<-shinyServer(function(input, output) {
output$dual <- reactive({ input$p == 'b' })
outputOptions(output, 'dual', suspendWhenHidden = FALSE)
output$file_area_1 <- renderUI({
message = 'Choose consolidated file'
if(input$p == 'b'){
message = 'Choose test file'
}else{
mesage = ''
}
fileInput("file1",message,
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
)
})
output$file_area_2 <- renderUI({
if(input$p == 'b'){
fileInput("file2","Choose control file",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
)
}
})
output$diff_headers <- renderUI({
if(input$p == 'b'){
checkboxInput('headercheckbox',
"Files have different headers?",
value = FALSE
)
}
})
})
shinyApp(ui,server)

Answer 2

I think if you allow the panels to define the condition based on the user input, you can get the functionality you want:
ui<-shinyUI(fluidPage(
sidebarLayout(
sidebarPanel(
radioButtons("p", "separate input files or consolidated?",
list("Single file"='a', "Separate files"='b'))
),
mainPanel(
conditionalPanel(
condition ="output.dual == 'a' " ,
fileInput("file1","Choose Consolodated file",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
)
),
conditionalPanel(
condition ="output.dual == 'b' " ,
fileInput("file1","Choose Test file",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
)
),
conditionalPanel(
condition = "output.dual == 'b'",
fileInput("file2", "Choose control file",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv","sas7bdat")
)
),
conditionalPanel(
condition = "output.dual == 'b'",
checkboxInput('headercheckbox',
"Files have different headers?",
value = FALSE
)
)### bracket close of conditional panel
)
)
))
server<-shinyServer(function(input, output) {
output$dual <- reactive({ input$p })
outputOptions(output, 'dual', suspendWhenHidden = FALSE)
})
shinyApp(ui,server)