modularized `excelInput()` in shiny

Question

I define a module to import excel. Hoping we can return the data and the name of excel to a global rv.

I observe the read event in console, I put a verbatimTextOutput() in UI, but the passing failed, print() always NULL, the value didn't return to the vectors I want.

Any advice would be greatly appreciated.

excelInput <- function(id) {
  ns <- NS(id)
  tagList(
    div(style = "margin-bottom: -15px;", fileInput(ns("excel"), label = ".csv, or .xlsx", accept = c(".csv", ".xlsx"), multiple = FALSE)),
    uiOutput(ns("sheetUI")),
    uiOutput(ns("readUI"))
  )
}

excelInputServer <- function(id, needRead, data_rv, name_rv = NULL) {
  moduleServer(id, function(input, output, session) {
    ns <- session$ns
    ext <- reactive({tools::file_ext(input$excel$name)})
    output$sheetUI <- renderUI({
      req(ext())
      if (ext() == "xlsx") {
        selectInput(ns("sheet"), "Sheet", choices = readxl::excel_sheets(input$excel$datapath))
      }
    })
    if (needRead == TRUE) {
      output$readUI <- renderUI({
        actionButton(ns("read"), "Read")
      })
      observe({
        shinyjs::toggleState("read", condition = !is.null(input$excel))
      })
      observeEvent(input$read, {
        if (ext() == "csv") {
          data_rv <- readr::read_csv(input$excel$datapath)
          if (!is.null(name_rv)) {
            name_rv <- stringr::str_extract(input$excel$name, ".*(?=\\.)")
          }
        } else if (ext() == "xlsx") {
          data_rv <- readxl::read_xlsx(input$excel$datapath, input$sheet)
          if (!is.null(name_rv)) {
            name_rv <- paste0(stringr::str_extract(input$excel$name, ".*(?=\\.)"), "_#", input$sheet, "#")
          }
        }
      })
    } else {
      observe({
        req(ext())
        if (ext() == "csv") {
          data_rv <- readr::read_csv(input$excel$datapath)
          if (!is.null(name_rv)) {
            name_rv <- stringr::str_extract(input$excel$name, ".*(?=\\.)")
          }
        } else if (ext() == "xlsx") {
          data_rv <- readxl::read_xlsx(input$excel$datapath, input$sheet)
          if (!is.null(name_rv)) {
            name_rv <- paste0(stringr::str_extract(input$excel$name, ".*(?=\\.)"), "_#", input$sheet, "#")
          }
        }
      })
    }
  })
}


library(shiny)
shinyApp(
  ui <- fluidPage(
    shinyjs::useShinyjs(),
    fluidRow(
      column(width = 4, excelInput("needRead")),
      column(width = 8, verbatimTextOutput("print1"))
    ),
    fluidRow(
      column(width = 4, excelInput("noRead")),
      column(width = 8, verbatimTextOutput("print2"))
    )
  ),
  server <- function(input, output, session) {

    rv <- reactiveValues()

    excelInputServer("needRead", TRUE, rv$data_test1, rv$filename_test1)
    output$print1 <- renderPrint({
      print(rv$filename_test1)
      print(rv$data_test1)
    })

    excelInputServer("noRead", FALSE, rv$data_test1)
    output$print2 <- renderPrint({
      print(rv$filename_test2)
      print(rv$data_test2)
    })
  }
)

Answer 1

I think you want something like that. You have to return some objects from the server module.

library(shiny)

excelInput <- function(id) {
  ns <- NS(id)
  tagList(
    div(style = "margin-bottom: -15px;", fileInput(ns("excel"), label = ".csv, or .xlsx", accept = c(".csv", ".xlsx"), multiple = FALSE)),
    uiOutput(ns("sheetUI")),
    uiOutput(ns("readUI"))
  )
}

excelInputServer <- function(id, needRead) {
  moduleServer(
    id, 
    function(input, output, session) {
      ns <- session$ns
      
      ext <- eventReactive(
        input$excel, {
          tools::file_ext(input$excel$name)
        })
      
      output$sheetUI <- renderUI({
        req(ext())
        if (ext() == "xlsx") {
          selectInput(ns("sheet"), "Sheet", choices = readxl::excel_sheets(input$excel$datapath))
        }
      })
      
      Data <- reactiveVal()
      Name <- reactiveVal()
      
      if(needRead) {
        output$readUI <- renderUI({
          actionButton(ns("read"), "Read")
        })
        
        observe({
          shinyjs::toggleState("read", condition = !is.null(input$excel))
        })
        
        observeEvent(input$read, {
          if (ext() == "csv") {
            dat <- readr::read_csv(input$excel$datapath)
            Data(dat)
            Name(stringr::str_extract(input$excel$name, ".*(?=\\.)"))
          } else if (ext() == "xlsx") {
            dat <- readxl::read_xlsx(input$excel$datapath, input$sheet)
            Data(dat)
            Name(paste0(stringr::str_extract(input$excel$name, ".*(?=\\.)"), "_#", input$sheet, "#"))
          }
        })
      } else {
        observe({
          req(ext())
          if (ext() == "csv") {
            dat <- readr::read_csv(input$excel$datapath)
            Data(dat)
            Name(stringr::str_extract(input$excel$name, ".*(?=\\.)"))
          } else if (ext() == "xlsx") {
            dat <- readxl::read_xlsx(input$excel$datapath, input$sheet)
            Data(dat)
            Name(paste0(stringr::str_extract(input$excel$name, ".*(?=\\.)"), "_#", input$sheet, "#"))
          }
        })
      }
      return(list(data = Data, name = Name))
    }
  )
}


library(shiny)
shinyApp(
  ui <- fluidPage(
    shinyjs::useShinyjs(),
    fluidRow(
      column(width = 4, excelInput("needRead")),
      column(width = 8, verbatimTextOutput("print1"))
    ),
    fluidRow(
      column(width = 4, excelInput("noRead")),
      column(width = 8, verbatimTextOutput("print2"))
    )
  ),
  server <- function(input, output, session) {
    
    x1 <- excelInputServer("needRead", TRUE)
    output$print1 <- renderPrint({
      print(x1$data())
      print(x1$name())
    })
    
    x2 <- excelInputServer("noRead", FALSE)
    output$print2 <- renderPrint({
      print(x2$data())
      print(x2$name())
    })
  }
)

Answer 2

Delay the reactive fraction of a second, and it works fine. Try this

library(readxl)

excelInput <- function(id) {
  ns <- NS(id)
  tagList(
    div(style = "margin-bottom: -15px;",
        fileInput(ns("excel"), label = ".csv, or .xlsx", accept = c(".csv", ".xlsx"), multiple = FALSE) ),
    shinyjs::hidden(selectInput(ns("sheet"), "Sheet", choices = c(Choose = "")))
  )
}

excelInputServer <- function(id) {
  moduleServer(id, function(input, output, session) {
    ns <- session$ns
    ext <- tools::file_ext(input$excel$name)
    
    observeEvent(input$excel, {
      req(ext)
      
      if (stringr::str_ends(input$excel$datapath, "(xlsx|xls)") ) {
        shinyjs::show("sheet")
        inFile <- input$excel            
        sheetnames <- excel_sheets(path = inFile$datapath)
        updateSelectInput(session, "sheet", choices = sheetnames)
      }else if (stringr::str_ends(input$excel$datapath, "csv")){  ### set sheets to NULL if csv is selected
        updateSelectInput(session, "sheet", choices = character(0))
        shinyjs::hide("sheet")
      }
    }, ignoreNULL = TRUE, ignoreInit = TRUE)

    myreturn <- reactive({
      req(ext,input$excel)
      Sys.sleep(0.3)
      if (ext == "csv") {
        file = str_extract(input$excel$name, ".*(?=\\.)")
        dt = read.csv2(input$excel$datapath)
      } else if (ext == "xlsx") {
        req(input$sheet)
        file = paste0(str_extract(input$excel$name, ".*(?=\\.)"), "_#", input$sheet, "#")
        dt = readxl::read_xlsx(input$excel$datapath, input$sheet)
      }
      return(list(
        filename = file,
        data = dt
      ))

    })

    return(myreturn)
  })
}

shinyApp(
  ui <- fluidPage(
    shinyjs::useShinyjs(),
    fluidRow(
      column(width = 4, excelInput("test")),
      column(width = 8, verbatimTextOutput("print"))
    )
  ),
  server <- function(input, output, session) {
    rv <- reactiveValues()
    observe({
      extract <- excelInputServer("test")
      rv$filename_test <- extract()[[1]]
      rv$data_test <- extract()[[2]]
    })
    output$print <- renderPrint({
      print(rv$filename_test)
      print(rv$data_test)
    })
  }
)