R Shiny选择dataframe后对应数据未在主面板显示问题求助

• 重复定义了同名响应式变量datasetInput与输出对象output$table，后定义的逻辑会直接覆盖前者，导致第一个下拉菜单的选择逻辑完全失效
• 两个下载按钮的id均为downloadData，Shiny要求UI组件id全局唯一，重复id会导致下载功能异常
• 每个下拉菜单的可选列表仅包含单个数据集，且switch逻辑未处理默认选中的SelectDataSet选项，选中默认值时会返回空值，导致表格无内容渲染
• 未实现两个下拉选择的联动逻辑，无法做到选中任意一个下拉的数据集都对应渲染表格

library(shiny)
data1 <- data.frame(
  SSN = c(500,1000,2000,3000,4000), 
  Name=c("Blossum","Buttercup","Bubbles","MojoJojo","Professor"), 
  Age = c(7,8,6,43,56), 
  Gender = c(0,0,0,1,1)
)

data2 <- data.frame(
  SSN = c(5000,6000,7000,8000,9000), 
  Name=c("Blossum","Buttercup","Bubbles","MojoJojo","Professor"), 
  Age = c(7,8,6,43,56), 
  Gender = c(0,0,0,1,1)
)

ui <- fluidPage(
  titlePanel("Downloading Data"),
  sidebarLayout(
    sidebarPanel(
      selectInput("dataset", "Choose a dataset:",
                  choices = c("SelectDataSet ", "data1")),
      downloadButton("downloadData1", "Download data1"),
      
      selectInput("dataset3", "View Summary:",
                  choices = c("SelectDataSet", "data2")),
      downloadButton("downloadData2", "Download data2")
    ),
    mainPanel(
      tableOutput("table")
    )
  )
)

server <- function(input, output) {
  # 统一处理两个下拉的选择逻辑，优先返回非默认选项的数据集
  datasetInput <- reactive({
    if(input$dataset == "data1") {
      return(data1)
    } else if(input$dataset3 == "data2") {
      return(data2)
    } else {
      return(NULL)
    }
  })
  
  output$table <- renderTable({
    datasetInput()
  })
  
  # 第一个下载按钮对应下载data1
  output$downloadData1 <- downloadHandler(
    filename = function() {
      "data1.csv"
    },
    content = function(file) {
      write.csv(data1, file, row.names = FALSE)
    }
  )
  
  # 第二个下载按钮对应下载data2
  output$downloadData2 <- downloadHandler(
    filename = function() {
      "data2.csv"
    },
    content = function(file) {
      write.csv(data2, file, row.names = FALSE)
    }
  )
}

shinyApp(ui, server)

• 选中第一个下拉的data1选项时，主面板自动渲染data1的内容
• 选中第二个下拉的data2选项时，主面板自动渲染data2的内容
• 两个下载按钮分别对应下载对应的数据集，互不干扰
• 两个下拉均选择默认的SelectDataSet选项时，主面板无表格展示

内容的提问来源于stack exchange，提问作者Kumar