将数据冲突错误 (409) 转换为客户可以理解的消息

Question

我对使用 R 和 Shiny 比较陌生。目前，我在尝试从 Dropbox 访问 html 文件时遇到错误：冲突（HTTP 409），这很好，我知道原因。我确实有一个问题是试图找到一种方法来更改错误代码消息。

我尝试了几种形式的验证和尝试捕获。

library(shiny)
library(rdrop2)
library(httr)

ui <- # Define UI for dataset viewer application

shinyUI(pageWithSidebar(

headerPanel("Test DropBox html Docs to Shiny"),  

sidebarPanel(

  selectInput("Cat", "Choose a Category:",

              choices = c("A", "B", "C")),

  selectInput("Year", "Choose a Year:",

              choices = c("2012", "2011")),

  downloadButton("downFile", "Download File"),

  width = 2), 

mainPanel(

  tabsetPanel(type = "tabs",

              tabPanel("Html Pages", htmlOutput("viewReport"))), 
 width   = 10)
)
)

#IMPORTANT: The two lines below needs to be run just one time unless the token is deleted

# Create Token
token <- drop_auth()

# Save token
saveRDS(token, "droptoken.rds")

token <- readRDS("droptoken.rds")

server <- shinyServer(function(input, output) { 

# ---------------------------------------------------  
  filePutReport <- reactive(

    paste(input$Cat, "_", input$Year, "_Doc.html", sep = "")   
  )

  filePutReport2 <- reactive({
    # Search if the file exists in DropBox

    drop_download(path = paste("shiny_docs/shinydbtest/", filePutReport(), sep = ""),
                  overwrite = TRUE, local_path = "./www",
             dtoken = token)

      filePutReport()
  })

  # Show Html Pages

  output$viewReport <- renderUI({

    tags$iframe(seamless = "seamless", width = "1400", height = "1000",

                src = filePutReport2()
                )
  })

  ###
  output$downFile <- downloadHandler(
    # generate bins based on input$bins from ui.R
    filename = function() {

      paste0(filePutReport() )
    },

    content = function(file){

      file.copy(from = paste0("./www/", filePutReport2() ), to = file, overwrite = TRUE)
    }   
  )
})

shinyApp(ui = ui, server = server)

而不是简单的“错误：冲突（HTTP 409）”，我希望客户端可能能够理解的消息。欢迎任何和所有建议。提前感谢您的帮助。

Answer 1

在我当前的环境中，我无法建立与 Dropbox 的连接，但请尝试以下方法。我首先删除了您的filePutReport2() 反应式中引用filePutReport() 的最后一行，因为它们是相同的，并且您希望对drop_download 的调用产生一个值（TRUE）或类“try-error”的不可见对象”。因此，您需要在try 语句中进一步包装对drop_download 的调用。这样filePutReport2() 要么包含值 TRUE，要么包含“try-error”类的不可见对象。然后您应该能够在您的renderUI 语句中使用need/validate function，包括自定义错误消息。我希望它能正常工作，因为我无法测试它。

library(shiny)
library(rdrop2)
library(httr)

ui <- # Define UI for dataset viewer application

  shinyUI(pageWithSidebar(

    headerPanel("Test DropBox html Docs to Shiny"),  

    sidebarPanel(

      selectInput("Cat", "Choose a Category:",

                  choices = c("A", "B", "C")),

      selectInput("Year", "Choose a Year:",

                  choices = c("2012", "2011")),

      downloadButton("downFile", "Download File"),

      width = 2), 

    mainPanel(

      tabsetPanel(type = "tabs",

                  tabPanel("Html Pages", htmlOutput("viewReport"))), 
      width   = 10)
  )
  )

#IMPORTANT: The two lines below needs to be run just one time unless the token is deleted

# Create Token
token <- drop_auth()

# Save token
saveRDS(token, "droptoken.rds")

token <- readRDS("droptoken.rds")

server <- shinyServer(function(input, output) { 

  # ---------------------------------------------------  
  filePutReport <- reactive(

    paste(input$Cat, "_", input$Year, "_Doc.html", sep = "")   
  )

  filePutReport2 <- reactive({
    # Search if the file exists in DropBox
    try({
    drop_download(path = paste("shiny_docs/shinydbtest/", filePutReport(), sep = ""),
                  overwrite = TRUE, local_path = "./www",
                  dtoken = token)
    }, silent = TRUE)

  })

  # Show Html Pages

  output$viewReport <- renderUI({

    validate(
      need(filePutReport2(), 'Custom error message!'))

    tags$iframe(seamless = "seamless", width = "1400", height = "1000",

                src = filePutReport()
    )
  })

  ###
  output$downFile <- downloadHandler(
    # generate bins based on input$bins from ui.R
    filename = function() {

      paste0(filePutReport() )
    },

    content = function(file){

      file.copy(from = paste0("./www/", filePutReport2() ), to = file, overwrite = TRUE)
    }   
  )
})

shinyApp(ui = ui, server = server)