在闪亮的应用程序中取消选择列或编辑数据表时，下载按钮消失 [英] download button disappear when deselecting column or editing data table in shiny app

问题描述

我构建了一个闪亮的应用程序，用于下载自定义和可编辑的数据表。这里以 iris 数据集为例。

I built a shiny app for downloading customized and editable data table. Here I use iris dataset as an example.

根据此 ，我添加了一个按钮，将整个数据集下载为csv。

According to this post, I add a button to download the whole dataset as csv.

但是，出现了一个问题。当我尝试取消选中某些列或编辑表时，下载按钮便消失了。而且它再也不会出现。

However, one issue came up. When I tried to uncheck some column OR edit table, the download button simply disappear. And it never show up again.

我花了数小时试图弄清楚，但没有成功。
有人知道为什么会这样吗？非常感谢。

I spend hours trying to figure it out but was unsuccessful. Does anyone know why that happens? Thanks a lot in advance.

library(shiny)
library(DT)
library(dplyr)


    # UI
    ui = fluidPage(
                   downloadButton("download1","Download iris as csv"),
                   DT::dataTableOutput('tbl'),
                   checkboxGroupInput('datacols', 
                                      label='Select Columns:',
                                      choices= c('Sepal.Length', 'Sepal.Width', 'Petal.Length', 'Petal.Width', 'Specie'),
                                      selected = c('Sepal.Length', 'Sepal.Width', 'Petal.Length', 'Petal.Width', 'Specie'),
                                      inline=TRUE )

                   )

    # SERVER
    server = function(input, output) {



        df = reactiveValues()

        observe ({

            df$dat = iris %>% select(one_of(input$datacols))
        })
        # render DT
        output$tbl = renderDT({
                datatable(df$dat,
                editable = "cell",
                callback = JS("$('div.dwnld').append($('#download1'));"),
                extensions = "Buttons",
                options = list(
                    dom = 'B<"dwnld">frtip',
                    buttons = list(
                        "copy" ) ) )

        })


        observeEvent(input[["tbl_cell_edit"]], {
            cellinfo <- input[["tbl_cell_edit"]]
            df$dat  <- editData(df$dat,  input[["tbl_cell_edit"]] )
        })

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

    }

shinyApp(ui, server)

推荐答案

非常有趣的情况。

每次编辑单元格或选择/取消选择列时，这都会更改 df $ dat ，然后重新呈现表。但是随后表中包含的元素＃download1 在DOM中不再存在。

Each time you edit a cell or select/unselect a column, this changes df$dat, and then the table is rerendered. But then the element #download1 which was included in the table does not exist anymore in the DOM.

找到一种方法来选择/取消选择某些列并编辑某些单元格而无需重新呈现表。这里是一个：

We have to find a way to select/unselect some columns and to edit some cells without rerendering the table. Here is one:

library(shiny)
library(DT)
library(dplyr)

# UI
ui = fluidPage(
  downloadButton("download1", "Download iris as csv"),
  DTOutput('tbl'),
  checkboxGroupInput(
    'datacols', 
    label='Select Columns:',
    choices= c('Sepal.Length', 'Sepal.Width', 'Petal.Length', 'Petal.Width', 'Species'),
    selected = c('Sepal.Length', 'Sepal.Width', 'Petal.Length', 'Petal.Width', 'Species'),
    inline=TRUE)

)

# SERVER
server = function(input, output) {

  dat <- iris

  # render DT
  output$tbl = renderDT({
    datatable(dat,
              editable = "cell",
              callback = JS(
                "$('div.dwnld').append($('#download1'));",
                "var checkboxes = $('input[name=datacols]');",
                "checkboxes.each(function(index,value){",
                "  var column = table.column(index+1);",
                "  $(this).on('click', function(){",
                "    if($(this).prop('checked')){",
                "      column.visible(true);",
                "    }else{",
                "      column.visible(false);",
                "    }",
                "  });",
                "});"
              ),
              extensions = "Buttons",
              options = list(
                dom = 'B<"dwnld">frtip',
                buttons = list("copy")
              ) 
    )

  })

  observeEvent(input[["tbl_cell_edit"]], {
    cellinfo <- input[["tbl_cell_edit"]]
    dat <<- editData(dat, cellinfo, "tbl")
  })

  output$download1 <- downloadHandler(
    filename = function() {
      paste("data-", Sys.Date(), ".csv", sep="")
    },
    content = function(file) {
      write.csv(dat %>% select(one_of(input$datacols)), file)
    }
  )

}

shinyApp(ui, server)

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