R-下载文件rshiny

Question

我有一个rshiny应用程序，并且在编辑后，我正在尝试从该应用程序下载CSV文件。我在线遵循了示例，但是下载按钮不起作用。我知道该按钮很好，它直接从rshiny文档中复制。我认为错误是服务器端

server <-function(input,output){# Combine the selected variables into a new data frame
#output$value <- renderPrint({
# str(input$GimmeCSV[2,2])
output$table.preview <- renderTable({
  inFile <- input$GimmeCSV
  preview <- read.csv(inFile$datapath, header=TRUE, sep=",")
  return(head(preview)) # undo Table can be modified 
})
output$table.output <- renderTable({
  inFile <- input$GimmeCSV
  tbl <- read.csv(inFile$datapath, header=TRUE, sep=",")
  #return(head(tbl)) # undo Table can be modified 
  ################^ preview of csv table################
  #look up how to extract the columns  with no name present(something numerical)
  #After that is figured out calculating the rest of those values will be a snap
  #tbl <- read.csv(inFile$datapath, header=TRUE, sep=",")
  #below is temporary file path only used for testing purposes, the above read.csv is the true pooba
  #STANDARDS!!!
  solar <- tbl$solar
  temp  <- tbl$temp
  ws    <- tbl$ws

  #return(head(solar))
  Ktemp <-temp + 273
  ktemp <-temp + 273 
  #lol
  if ((input$Shape) == shape_select[1]){
    Len <- (input$diacone)
    Height <- (input$hgtcone)
    Width <- 0
  } else {if((input$Shape) == shape_select[2]){
    Len <- (input$diasphere)
    Height <- 0
    Width <- 0
  } 
    else 
      Len <- (input$lenprism)
    Height <- (input$hgtprism)
    Width <- (input$widprism)
  }
  r <-Len/2
  #return(r)

  if (Len >=0.037){  # Absorptivity from Luke Miller 
    Abs <- 0.615
  } else {if (Len <= 0.02225 ){Abs <-0.689
  } else Abs <- 0.68 } 
  #works!
  Emm <-0.97
  #TOTALLY ARBITURARY SURFACE AREA VALUES BASED ON WHAT I KNOW!
  ConeA <- (pi*r*r) + (sqrt((Height*Height)+(r*r))) # area of cone
  SphereA <- (4*pi*(r*r)) #area of sphere
  PrismA <- ((2*Len*Width) + (2*Height*Len) +( 2*Height*Width))
  #return(PrismA) 
  #WORKS
  #Deciding which surface area area to calculate
  if ((input$Shape) == shape_select[1]){
    SA <-ConeA
  } else {if((input$Shape) == shape_select[2]){SA <- SphereA} 
    else SA <-PrismA}

  #WOEKS!!!!!!!
  #return(SA)
  #Temporary placeholder values for PSA
  PSA <- SA
  SB <- 5.67E-08 # Stephan Boltzman constant
  eskyclear <- 0.72 + (0.005*temp)
  CC <- 0.5 #Cloud over 0 - 1
  esky <- eskyclear + CC*(1 - eskyclear - (8/ktemp)) #IR emissivity from sky
  Aradsky <- SA/2 #surface area projected to the sky
  Aradground <- SA/2 # surface area projected to the ground
  K3 <- esky^(1/4)
  K2 <- 4 * SB * Emm * (esky)^(3/4)
  K4 <- 4 * SB * Emm
  K5 <- 0.6/(0.5*Len)
  hc <- 0.6

  com1 <- (Abs * solar) + (K2 * (Aradsky/PSA) * K3 * Ktemp^4) + (K4 * (Aradground/PSA) * Ktemp^4) + (K5 * PSA * Ktemp) + (hc*SA*Ktemp) + 2.48*0
  com2 <- (4180 * 0) + ((Ktemp^3) * K2 * (Aradsky/PSA)) + (K4 * (Aradground/PSA) *(Ktemp^3)) + (hc*SA) + (K5*PSA)
  #works!
  Sol <- com1 / com2
  modeltemp <- Sol - 273
  max <- max(modeltemp)
  min <- min(modeltemp)


  mydata <- data.frame( Daily_Temp = temp, Solar_Radiation = solar, Body_Temperature = modeltemp, stringsAsFactors = FALSE)
  return(mydata)

  output$downloadData <- downloadHandler(
    filename = function() { paste(input$inFile, '.csv', sep='') },
    content = function(file) {
      write.csv(mydata, file)
    }
  )
})
  } #app goes here lol
  shinyApp(ui, server)
}

任何subestions均被赞赏

Answer 1

我对您的代码进行了重新排列，并在服务器函数开头创建了2个反应值。

在observeEvent中，您要等到fileInput -Button( Input $ gimmecsv (单击，然后读取CSV，然后将其分配给反应性值inputFile。然后，您可以在两个renderTable输出中直接访问此值，因为您将在示例中加载CSV。如果文件不太大，则不应该是问题，但不是必需的。

downloadHandler进入renderTable函数之外，并采用输入参数( input $ infile (，该函数用于命名输出文件。对于内容，使用了第二个反应值，在output$table.output中分配了数据。

library(shiny)
ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      fileInput("GimmeCSV", "Upload a CSV", multiple = F),
      textInput("inFile", "Name for Output"),
      downloadLink("downloadData", "Download")
    ),
    mainPanel(
      tableOutput("table.preview"),
      tableOutput("table.output")
    )
  )
)

server <-function(input,output){
  inputFile <- reactiveValues(file = NULL)
  outputFile <- reactiveValues(file=NULL)
  observeEvent(input$GimmeCSV, {
    inFile <- input$GimmeCSV
    data <- read.csv(inFile$datapath, header=TRUE, sep=";")
    inputFile$file <- data
  })
  output$table.preview <- renderTable({
    head(inputFile$file)
  })
  output$table.output <- renderTable({
    tbl <- inputFile$file
    outputFile$file <- tbl
    tbl
  })
  output$downloadData <- downloadHandler(
    filename = function() {
      paste(input$inFile, '.csv', sep='')
    },
    content = function(file) {
      write.csv(outputFile$file, file)
    }
  )
}
shinyApp(ui, server)

希望它有帮助。