显示shinyapp中.csv的textInput的反应值

Question

我正在开发一个shinyapp，用于交互式地生成一个包含文件名称和一些新文本或注释的表格。 目前它按照以下步骤工作：
1.选择文件夹
2.使用文件名创建.csv（如果没有）
.csv的名称遵循模式“subfolderName”.csv
3.使用selectInput选项选择文件名
4.将每行（文件）的注释添加到.csv文件中 第二栏名为“评论”

我不能做的一些理想行为：
- 在文本字段（注释）中显示当前所选文件名（保存在.csv中）的上一个注释（如果有）。我也试过updateTextInput并且没有用。

#save as app.R
library(shiny)
library(shinyFiles)
library(shinyBS)
library(dplyr)
ui <- fluidPage(sidebarLayout(
  sidebarPanel(
    shinyDirButton("dir", "1. Choose directory", "Upload")
    ,br(),br()
    ,  bsButton("submit","2. Create or reset .csv", style="warning")
    ,br(),br()
    , uiOutput("fileinput")
    , uiOutput("uitextinput") # this is not showing existing comments

    ,  bsButton("addname","4. Add comment", style="warning")
  ),
  mainPanel(
    h4("Selected folder"),
    verbatimTextOutput("dirtext"), br(),
    h4("Files in that dir"),
    verbatimTextOutput("files"),
    textOutput("result")
  )
)) 

path1<-"~"

server <- function(input, output, session) {
  output$result<-renderText({
    t<- reac$message
  })

  shinyDirChoose(input, 'dir', roots = c(home = path1) )
  reacdir <- reactive(input$dir)
  output$dirtext <- renderPrint(c(path(),current() ) )

  path <- reactive({
    home <- normalizePath(path1)
    file.path(home, paste(unlist(reacdir()$path[-1]), collapse = .Platform$file.sep))
  })

  current<-reactive({
    a<-sub('.*\\/', '', path() )  
    b<-paste("current subdir:",a)
  })

  reac <- reactiveValues(comment=NULL, df2=NULL)

  #not WORKING
  output$uitextinput<-renderUI(
    textInput("commentwritten","Comment for file", reac$comment)
  )

  # GET current .csv file with comments and load the comment to reac$comment , Not working
  observe({
    validate(
      need(try(any(class(reactiveFileReader(1000, session, paste0(path(),"/",sub('.*\\/', '', path() ),".csv") , 
                                            read.csv()))=="data.frame")==TRUE), "Wait 801")
    )       
    reac$df2<-  reactiveFileReader(1000, session, paste0(path(),"/",sub('.*\\/', '', path() ),".csv") , read.csv, stringsAsFactors=FALSE)
    reac$comment<-reac$df2$comment[match(input$file, reac$df2$name)]
  })

  filedata<-reactive({
    filenames<-  list.files(path())
    filedata<-data.frame(name=filenames)
  })

  # button 2. creating the csv file
  observeEvent(input$submit,{
    write.csv(filedata(), file =paste0(path(),"/",sub('.*\\/', '', path() ),".csv")  , row.names = FALSE ) 
  })

  #step 3
  output$fileinput<-renderUI(
    div(style="width: 100%; margin: 0 0;",
        selectInput("file", "3. Select filename to add details", filedata()$name)
    )
  )

  #step 4, adding a comment to the .csv 
  observeEvent(input$addname , {
    if(file.exists(paste0(path(),"/",sub('.*\\/', '', path() ),".csv")) ){
    dfnameadded <- reactive({
      originaldf<-reactiveFileReader(1000, session, paste0(path(),"/",sub('.*\\/', '', path() ),".csv") , read.csv, stringsAsFactors=FALSE)
      filetoadd <- data.frame(name=input$file , stringsAsFactors = FALSE)
      filetoadd$comment<-input$commentwritten
      l<-list(originaldf(),filetoadd)#
      dfadded<- Reduce(bind_rows, l)
      dfadded<-dfadded %>%
        group_by(name) %>%
        summarise(comment = paste0(na.omit(comment[length(comment)]), collapse = "; ") )
      dfadded
    })
    tryCatch(write.csv(dfnameadded(), file =paste0(path(),"/",sub('.*\\/', '', path() ),".csv")  , row.names = FALSE ), 
             error = function(e) {print(paste("create .csv first")) ; "create .csv first" } )
    reac$message<-"comment added"
    }
    else
    {
    reac$message<-"create .csv first"  
    }
  })

  output$files <- renderPrint(list.files(path()))
} # end server 
shinyApp(ui, server) 

Answer 1

我来到这个解决方案 替换

struct timeval t1, t2;
gettimeofday(&t1, NULL);
gettimeofday(&t2, NULL);
int milliSeconds = (t2.tv_sec - t1.tv_sec) * 1000 + (t2.tv_usec - t1.tv_usec)/1000;

使用：

  #not WORKING
  # output$uitextinput<-renderUI(
  #   textInput("commentwritten","Comment for file", reac$comment)
  # )

Answer 2

试试这个：

reac <- reactiveValues(comment <- NULL, df <- NULL)
textInput("namewritten","Comment for photo",placeholder= if(is.null(reac$comment)){"No Comments"}else{reac$comment})

我也将df作为反应值。你使用一个观察基本上调用一个被动函数，但观察不会返回任何值，所以重新$ comment没有被返回。