渲染UI，ObserveEvent和查询数据库的反应性问题

Question

我创建了一个简单的CRUD系统，以管理我用于使用R Shiny和Rhandsontable进行建模的数据。

每次我在R Shiny中更改此表（“模型表”）中的内容，然后单击“保存”按钮时，我的表就会在数据库中更新

然后我有第二个面板，可以在列表中选择所需的模型（这些模型名称来自您在上面的表中看到的->这是相同的查询）并修改所需的功能（“功能表格”）。

假设我通过修改表格来添加新行并保存（将信息发送到数据库的操作）：

我的问题是在执行此操作后，我的selectInput没有更新。

我没有得到的是我查询的代码块是“反应性的”，所以我认为每次我按下“保存”按钮时，“ data_model”函数都会再次运行。

我尝试了几种无效的方法：

1. 对查询使用eventReactive： 在我按下“保存”按钮之前，下拉菜单不起作用
2. 将updateSelectinput放在observeEvent中： 不起作用（而且我对observeEvent不熟悉，因此我不确定它的实际作用）

当我按下“保存”按钮时，如何更新我的renderUI下拉菜单。

这是我的代码：

  ##################
  #  MODEL TABLE   #
  ##################

# That part query the information from the model table

  data_model <- reactive({

    con <- dbConnect(odbc(),
                     Driver = "**********",
                     Server = "**********",
                     Database = "**********",
                     UID = "**********",
                     PWD = "**********")

    query <- "SELECT * FROM dbo.**********"

    df <- dbGetQuery(con, query)

    dbDisconnect(con)

    df
  })

  # This is the hansontable I get on my shiny App

  output$in.table <- renderRHandsontable({
    rhandsontable(data_model (), rowHeaders = NULL)
  })

  # This observeEvent is used to save my table when I push on 
  # the Save actionbutton

  observeEvent(input$Save, {

    df <- hot_to_r(input$in.table)

    con <- dbConnect(odbc(),
                     Driver = "**********",
                     Server = "**********",
                     Database = "**********",
                     UID = "**********",
                     PWD = "**********")


    if (dbExistsTable(conn = con,
                      name = "**********"))
    {dbRemoveTable(conn = con,
                   name = "**********"
    )}

    dbWriteTable(conn = con,
                 name = "**********",
                 value = df)

    dbDisconnect(con)

    })


  ####################
  #  FEATURE TABLE   #
  ####################

  # This query is used to retrieve the table corresponding to the model 
  # selected in my drop-down menu in the second printscreen. If the table 
  # does not exist, then a template table is loaded

  datafeatures <- reactive({

    con <- dbConnect(odbc(),
                     Driver = "**********",
                     Server = "**********",
                     Database = "**********",
                     UID = "**********",
                     PWD = "**********")

    features_table_name <- paste("**********", as.character(input$modelnamefeat), sep ='')

    if (dbExistsTable(conn = con,
                      name = "**********"))
    {
      query <- paste("SELECT * FROM dbo.", as.character(input$modelnamefeat), sep = '')

      df <- dbGetQuery(con, query)
    }

    else
    {

      query <- paste("SELECT * FROM dbo.**********")

      df <- dbGetQuery(con, query)

    }

    dbDisconnect(con)

    df})

  output$feat.table <- renderRHandsontable({
    rhandsontable(datafeatures(), rowHeaders = NULL)
  })


  # This is the input/output that I use to get my dropdown menu and 
  # that does not updated AKA my problem right now

  output$modelnamefeat <- renderUI({
    mydata <- data_model ()
    mydata1 <- sort(unique(mydata$model_name))
    selectInput(inputId = 'modelnamefeat', label = 'Model Name', choices = mydata1)
  })

  # This observeEvent has the same logic as the first one and is used to 
  # store my feature table in the correct table on SQL

  observeEvent(input$Savefeat, {
    df <- hot_to_r(input$feat.table)

    con <- dbConnect(odbc(),
                     Driver = "**********",
                     Server = "**********",
                     Database = "**********",
                     UID = "**********",
                     PWD = "**********")

    features_table_name <- paste("**********", as.character(input$modelnamefeat), sep ='')

    if (dbExistsTable(conn = con,
                      name = features_table_name))
    {dbRemoveTable(conn = con,
                   name = features_table_name
    )}

    dbWriteTable(conn = con,
                 name = features_table_name,
                 value = df)

    dbDisconnect(con)

  })