csv - Update on File Upload Shiny R -

i trying add file upload feature shiny app. ideally, want user able upload csv file , select variable want use dropdown menu. when app starts, have dataset preloaded , dropdown displays correct variable names dataset. however, when try upload different csv file, cannot seem dropdown update display variables contained in uploaded csv. here's code:

server.r

library(shiny) library(ggplot2)  infile <- mtcars  shinyserver(function(input, output) {    tabledata <- reactive({     infile <<- input$file1      if (!is.null(infile)){         read.csv(infile$datapath, header=input$header, sep=input$sep,                                                    quote=input$quote)     }     else {         infile <<- mtcars     }   })    #for x values   output$opt.x <- renderui({          selectinput("xcolumn", "x column plot", names(infile))   }) }) 

ui.r

library(shiny)  shinyui(fluidpage(      titlepanel("app"),         sidebarlayout(             sidebarpanel(                 fileinput('file1', 'choose csv file',                      accept = c(                             '.csv',                             '.tsv')                 ),                 uioutput("opt.x")              ),     mainpanel() )) 

i've tried placing output$opt.x assignment inside reactive function reads in file, didn't seem help.

hi don't pass variable global environnement, use shiny reactive feature instead, server should :

library(shiny) library(ggplot2)  # test data # write.csv(x = iris, file = "iris.csv", row.names = false) # write.csv(x = data.frame(v1 = 1:10, v2 = rnorm(10)), file = "test.csv", row.names = false)  shinyserver(function(input, output) {    tabledata <- reactive({     infile <- input$file1      if (!is.null(infile)){       read.csv(infile$datapath)     } else {       mtcars     }   })    #for x values   output$opt.x <- renderui({     selectinput("xcolumn", "x column plot", names(tabledata()))   })   output$your_data <- rendertable({    head(tabledata())  }) }) 

and replace main panel :

mainpanel(   tableoutput("your_data") ) 

i remove params in read.csv since input not defined in ui.

edit

try app, it's not shiny solution jquery/js 1 (the difference in ui) (see this answer) :

library("shiny") ui <- fluidpage(   titlepanel("app"),   sidebarlayout(     sidebarpanel(       fileinput('file1', 'choose csv file',                 accept = c('.csv','.tsv')       ),       tags$script(         '$( "#file1" ).on( "click", function() {           this.value = null;          });'       ),       uioutput("opt.x")     ),     mainpanel(       tableoutput("your_data")     )     )   ) server <- function(input, output) {    tabledata <- reactive({     infile <- input$file1     if (!is.null(infile)){       read.csv(infile$datapath)     } else {       mtcars     }   })   #for x values   output$opt.x <- renderui({     selectinput("xcolumn", "x column plot", names(tabledata()))   })    output$your_data <- rendertable({     head(tabledata())   }) } shinyapp(ui = ui, server = server) 

for testing used :

write.csv(x = data.frame(v1 = 1:10, v2 = rnorm(10)), file = "test.csv", row.names = false) write.csv(x = data.frame(v11 = 11:20, v12 = rnorm(10), abc = letters[1:10]), file = "test.csv", row.names = false)