R Shiny App- Data Table output not rendering

Question

Below is the code I have for my shiny app. The ultimate goal is for the user to upload 2 csv files that have the same column titles and the output should be the rows that are different between the 2 csv files. The app seems to upload the csv files OK, but there is no table shown in the shiny app. Additionally, I hope to export the full output table to a csv eventually, but I have yet to include that in my code.

library(shiny)
library(dplyr)
library(gridExtra)
library(grid)
library(stringr)
ui <- fluidPage(
  titlePanel("Uploading Files"),
  sidebarLayout(
    sidebarPanel(
      fileInput("file1", "Choose First Data File",
                    multiple = FALSE, accept = c("text/csv", "text/comma-separated-values, text/plain",
                                             ".csv")),
      fileInput("file2", "Choose Second Data File",
                multiple = FALSE, accept = c("text/csv", "text/comma-separated-values, text/plain",
                                             ".csv")),
      tags$hr(),
      checkboxInput("header", "Header", TRUE),
      radioButtons("sep", "Separator", choices = c(Comma = ",",
                                                   Semicolon = ";",
                                                   Tab = "\t"),
                   selected = ","),
      radioButtons("quote", "Quote", choices = c(None = "",
                                                 "Double Quote" = '"',
                                                 "Single Quote" = "'"),
                   selected = '"'),
      tags$hr(),
      radioButtons("disp", "Display", choices = c(Head = "head", All = "all"), selected = "head")
    ),
    mainPanel(
      tableOutput("contents", "export")
    )
  )
)
options(shiny.maxRequestSize = 30*1024^2)
server <- function(input, output) {
  data <- reactive({
    df <- read.csv(input$file1$datapath,
               header = input$header
               quote = input$quote)
    df2 <- read.csv(input$file2$datapath,
                header = input$header
                quote = input$quote)
    df$COLUMNA <- str_replace_all(df$COLUMNA, "[[:punct:]]", "")
    df2$COLUMNA <- str_replace_all(df2$COLUMNA, "[[:punct:]]", "")
    diff_df <- anti_join(df, df2, by = c("COLUMNA", "COLUMNB", "COLUMNC"))
    return(diff_df)
  }) 
}
output$contents <- renderTable({
  req(input$file1, input$file2)
  if(input$disp == "head") {
    head(data()$diff_df)
  }
  else {data()$diff_df}
})

shinyApp(ui, server)

Could you add 2 example .csv files in the proper format so we can try to reproduce your problem? — divibisan
– divibisan, Commented Sep 14, 2018 at 15:43
Some random thoughts: 1) add req(input$file1, input$file2) to data<-reactive({, since that can't run without both. 2) Load each file in a separate reactive, then merge them in a 3rd reactive. 3) rename data since it clashes with the built in data() function (unlikely to be the problem, but it's good practice) — divibisan
– divibisan, Commented Sep 14, 2018 at 15:54

Jim Chen · Accepted Answer · 2018-09-15 03:50:54Z

1

Have you tried to move the following code into your server function?

output$contents <- renderTable({
  req(input$file1, input$file2)
  if(input$disp == "head") {
    head(data()$diff_df)
  }
  else {data()$diff_df}
})

This renderTable should work in server function, but it seems you put it out of server.

answered Sep 15, 2018 at 3:50

Jim Chen

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