下载反应性数据框/数据表问题

Question

我是 R 新手，但我的任务是创建一个有效的下载按钮，该按钮会将查询表中的数据下载到 .csv 文件。目前，我无法理解应该传递给 write.csv() 函数的内容。我知道我必须使查询表具有反应性，但我也不确定如何做到这一点。我当前的代码遇到的错误是“ 不能将类'c("datatables", "htmlwidget")'强制转换为data.frame"

我尝试将我的 df() 函数作为参数传递，但它不起作用。

#ui
column(3, 
                         conditionalPanel("input.table.period != '1980'", 
                                          # only prompt for rcp if a future period (not historical)
                                          # input: select rcp
                                          selectInput("table.rcp", "Emissions Scenario:", 
                                                      c("Medium" = "45",
                                                        "High" = "85")),
                                          downloadButton('downloadData', 'Download')
                                          )


#server  
server <- function(input, output) {
currentdf <- reactive({


# build query based on user-selections
if (input$table.stype == "ann") {
  col.name <- columns.annual[grep(input$table.var, columns.annual)]
  if (input$table.period == "1980") {
    query <- paste0("SELECT ", col.name, ", subbasin, gcm_id FROM hydro_ann WHERE (period = ", input$table.period,
                    ")")
  } else {
    query <- paste0("SELECT ", col.name, ", subbasin, gcm_id FROM hydro_ann WHERE (period = ", input$table.period,
                    ") AND (rcp = ", input$table.rcp, ")")
  }
} else {
  col.name <- columns.month[grep(input$table.var, columns.month)]
  if (input$table.period == "1980") {
    query <- paste0("SELECT ", col.name, ", subbasin, gcm_id, calendar_month FROM hydro_month WHERE (period = ", input$table.period,
                    ")")
  } else {
    query <- paste0("SELECT ", col.name, ", subbasin, gcm_id, calendar_month FROM hydro_month WHERE (period = ", input$table.period,
                    ") AND (rcp = ", input$table.rcp, ")")
  }
}


df <- dbGetQuery(db, query)

DT::df


  })
  output$querytable <- renderTable({ DT::datatable(currentdf()) })
  output$downloadData <- downloadHandler(
filename = function() {
  paste("QueriedData", "csv", sep = ".")
},
content = function(file) {
  write.csv(as.data.frame(currentdf()),file)
}

Answer 1

我尝试了一个解决方案宽度 Iris 数据集，它可以让您在根据您选择的选项下载数据之前选择要保存的数据类型...

library(shiny)
library(shinydashboard)
library(DT)
library(datasets)
library(xlsx)

ui <- dashboardPage(
  dashboardHeader(title = "Basic dashboard"),
  dashboardSidebar(),
  dashboardBody(
    # Boxes need to be put in a row (or column)
    fluidRow(
      box(
        DTOutput("dtable")
          )
    )
  )
)

server <- function(input, output) {
  myModal <- function() {
    div(id = "Download_DATA",
        modalDialog(downloadButton("download1","Download iris as CSV"),
                    br(),
                    br(),
                    downloadButton("download2","Download iris as XLSX"),
                    easyClose = TRUE, title = "Download Table")
    )
  }

  output$dtable <- renderDT(
    datatable(iris,
              extensions = 'Buttons',
              options = list(
                dom = 'Bfrtip',
                buttons = list(
                  list(
                    extend = "collection",
                    text = 'Download',
                    action = DT::JS("function ( e, dt, node, config ) {
                                    Shiny.setInputValue('Download_DATA', true, {priority: 'event'});
}")
                  )
                    )
                  )
                )
              )

  observeEvent(input$Download_DATA, {
    showModal(myModal())
  })


  output$download1 <- downloadHandler(
    filename = function() {
      paste("data-", Sys.Date(), ".csv", sep="")
    },
    content = function(file) {
      write.csv(iris, file)
    }
  )

  output$download2 <- downloadHandler(
    filename = function() {
      paste("data-", Sys.Date(), ".xlsx", sep="")
    },
    content = function(file) {
      write.xlsx(iris, file)
    }
  )

}

shinyApp(ui, server)

请告诉我....