rHandsontable 下拉列表不保留 Shiny 应用程序中的编辑的问题？答案

【问题标题】：Issue with rHandsontable dropdown not preserving edits in Shiny app?rHandsontable 下拉列表不保留 Shiny 应用程序中的编辑的问题？
【发布时间】：2020-01-14 18:35:09
【问题描述】：

我已经构建了一个 Shiny 应用程序，它提示用户输入作为行动态添加到 rHandsontable 的输入。用户可以添加行、编辑行，然后添加更多行。该应用程序正在正常工作，但创建为 hot_cols 且 type = 'dropdown' 的列除外。用户对这些列所做的任何编辑都不会保留到下次添加行时，但所有其他编辑都会保留。

下面是我的应用程序。保留对 word 列的编辑，但不会保留对由 hot_col() 创建的 color 列的编辑。

library(shiny)
library(rhandsontable)
library(dplyr)

ui <- fluidPage(
    fluidRow(
        textAreaInput('wordlines', "Enter words separated by newlines"),
        actionButton('submit', "Submit Words"),
        rHandsontableOutput('hot')
    )
)

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

    colors <- c("red", "orange", "yellow", "green", "blue", "indigo", "violet")

    build_df <- function(input) {
        data.frame(
            word = unlist(strsplit(input$wordlines, "\n")),
            number = sample(100, 1),
            color = NA,
            stringsAsFactors = FALSE
        )
    }

    values <- reactiveValues()

    observeEvent(input$submit, {

        req(input$wordlines)

        if(input$submit == 1) { # if button pressed the first time
            values$df <- build_df(input)
        } else {
            tmp <- hot_to_r(input$hot)
            values$df <- bind_rows(tmp, build_df(input)) # add new rows to values$DF
        }

        updateTextAreaInput(session, 'wordlines', value = "") # clear textAreaInput

        output$hot <- renderRHandsontable({
            rhandsontable(values$df, overflow = 'visible') %>% hot_col(col = "color", type = "dropdown", source = colors) # dropdown column which, when edited, should preserve those edits through future adding of rows ('submit' button presses)
            })
    })
}

# Run the application 
shinyApp(ui = ui, server = server)

【问题讨论】：

标签： shiny rhandsontable

【解决方案1】：

有两点需要调整：

“颜色”列应初始化为字符。
将render* 函数包装在observeEvent 中是不好的做法

这是您的代码的工作版本：

library(shiny)
library(rhandsontable)
library(dplyr)

ui <- fluidPage(
  fluidRow(
    textAreaInput('wordlines', "Enter words separated by newlines"),
    actionButton('submit', "Submit Words"),
    p(),
    rHandsontableOutput('hot')
  )
)

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

  colors <- c("red", "orange", "yellow", "green", "blue", "indigo", "violet")

  build_df <- function(input) {
    data.frame(
      word = unlist(strsplit(input$wordlines, "\n")),
      number = sample(100, 1),
      color = NA_character_,
      stringsAsFactors = FALSE
    )
  }

  values <- reactiveValues()

  observeEvent(input$submit, {

    req(input$wordlines)

    if(input$submit == 1) { # if button pressed the first time
      values$df <- build_df(input)
    } else {
      tmp <- hot_to_r(input$hot)
      values$df <- bind_rows(tmp, build_df(input)) # add new rows to values$DF
    }

    updateTextAreaInput(session, 'wordlines', value = "") # clear textAreaInput
  })

  output$hot <- renderRHandsontable({
    req(values$df)
    rhandsontable(values$df, overflow = 'visible') %>% hot_col(col = "color", type = "dropdown", source = colors) # dropdown column which, when edited, should preserve those edits through future adding of rows ('submit' button presses)
  })

}

# Run the application 
shinyApp(ui = ui, server = server)

【讨论】：