CODEWITHSUNDEEP
rshinyshinydashboard
Dr. Dadkdhah
Dr. Dadkdhah

Reputation: 21

The output table did not display in R Shiny app

I wrote an R script by using shiny app. This script should read any input CSV file and shows it on the shiny user interface as the table. I attached my code. When I run the script, I can select s CSV file, but the output table does not display. Could you please help me?

library(shiny)
library(DT)
ui <- fluidPage(
  
  sidebarLayout(
    sidebarPanel(
      fileInput("file1", "Choose CSV File",
                accept = c(
                  "text/csv",
                  "text/comma-separated-values,text/plain",
                  ".csv")
      ),
      tags$hr(),
      checkboxInput("header", "Header", TRUE)
    ),
    mainPanel(
       # tableOutput('dto')
      dataTableOutput('dto'),
    )
  )
)

server <- function(input,output){
  # Reactive expression with the data, in this case iris
#----------------
  output$contents <- reactive({
    # input$file1 will be NULL initially. After the user selects
    # and uploads a file, it will be a data frame with 'name',
    # 'size', 'type', and 'datapath' columns. The 'datapath'
    # column will contain the local filenames where the data can
    # be found.
    inFile <- input$file1
    
    if (is.null(inFile))
      return(NULL)
    
    read.csv(inFile$datapath, header = input$header),
    
  })
#----------------
  
  #the extensions parameter coupled with the options list does the trick  
  output$dto <- renderDataTable(contents(), extensions = 'Buttons', 
                                options = list(dom = 'Bfrtip',
                                               buttons = c('copy', 'csv', 'excel', 'pdf', 'print'))
  )
}

runApp(list(ui=ui,server=server), launch.browser=TRUE) #now runs by default in the external browser.

Upvotes: 2

Views: 829

Answers (1)

NelsonGon
NelsonGon

Reputation: 13319

The principles of reactivity specify that we do not need to add reactive components to output. For contents, we simply make it reactive and access it whenever we need.

library(shiny)
library(DT)
?runApp
ui <- fluidPage(
  
  sidebarLayout(
    sidebarPanel(
      fileInput("file1", "Choose CSV File",
                accept = c(
                  "text/csv",
                  "text/comma-separated-values,text/plain",
                  ".csv")
      ),
      tags$hr(),
      checkboxInput("header", "Header", TRUE)
    ),
    mainPanel(
      # tableOutput('dto')
      dataTableOutput('dto'),
    )
  )
)

server <- function(input,output){
  # Reactive expression with the data, in this case iris
  #----------------
  contents <- reactive({
    # input$file1 will be NULL initially. After the user selects
    # and uploads a file, it will be a data frame with 'name',
    # 'size', 'type', and 'datapath' columns. The 'datapath'
    # column will contain the local filenames where the data can
    # be found.
    inFile <- input$file1
    
    if (is.null(inFile)) return(NULL)
    
    read.csv(inFile$datapath, header = input$header)
    
  })
  #----------------
  
  #the extensions parameter coupled with the options list does the trick  
  output$dto <- renderDataTable(contents(), extensions = 'Buttons', 
                                options = list(dom = 'Bfrtip',
                      buttons = c('copy', 'csv', 'excel', 'pdf', 'print'))
  )
}

runApp(list(ui=ui,server=server), launch.browser=TRUE)

Upvotes: 2

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