Showing head of multiple Excel files in Shiny

Question

I am trying to upload two Excel files in Shiny app. After uploading it should show headof those files. I am trying the following chunk:

library(shiny)
library(readxl)

# UI component

ui <- fluidPage(
  
  titlePanel("Upload Excel file"),
  
  sidebarLayout(sidebarPanel(
    
    fileInput('file1', 'Choose first file',
              accept = c(".xlsx"),
              buttonLabel = "Upload",
              multiple = TRUE),
    
    fileInput('file2', 'Choose second file',
              accept = c(".xlsx"),
              buttonLabel = "Upload",
              multiple = TRUE)
    ),

    mainPanel(
      tableOutput('contents')
    )
    
    
  ))

# Server component 

server <- function(input, output, session){
  
  output$contents <- renderTable({
    
    req(input$file1)
    
    inFile <- input$file1
    
    read_excel(inFile$datapath, 1)
    
    req(input$file2)
    
    inFile <- input$file2
    
    read_excel(inFile$datapath, 1)
    }
  )
  }

# Run the application 
shinyApp(ui = ui, server = server)

As one can see, it shows only one file.

Is there any way I can see head of both files?

Answer 1

The issue is that your renderTable is returning or rendering only the second table read with the second read_excel. If you want to render multiple tables you have to bind them into one or use multiple renderTables as I do in the code below which could be easily generalized for more than just two tables:

library(shiny)
library(readxl)

writexl::write_xlsx(mtcars, "mtcars.xlsx")
writexl::write_xlsx(iris, "iris.xlsx")

ui <- fluidPage(
  titlePanel("Upload Excel file"),
  sidebarLayout(
    sidebarPanel(
      fileInput("file1", "Choose first file",
        accept = c(".xlsx"),
        buttonLabel = "Upload",
        multiple = TRUE
      ),
      fileInput("file2", "Choose second file",
        accept = c(".xlsx"),
        buttonLabel = "Upload",
        multiple = TRUE
      )
    ),
    mainPanel(
      uiOutput("tables")
    )
  )
)

datasets <- list(mtcars, iris)

server <- function(input, output, session) {
  output$tables <- renderUI({
    table_output_list <- lapply(1:2, function(i) {
      table_name <- paste0("table", i)
      tableOutput(table_name)
    })

    do.call(tagList, table_output_list)
  })

  lapply(1:2, function(i) {
    table_name <- paste0("table", i)
    output[[table_name]] <- renderTable({
      req(input[[paste0("file", i)]])
      
      inFile <- input[[paste0("file", i)]]
      
      head(read_excel(inFile$datapath, 1))
    })
  })
}

shinyApp(ui = ui, server = server)