How to update dropdown list based on the output of action button in shiny?

Question

I have written a code that does the following

1) A simple dashboard page that has various tabs

2) One such tab is upload file, where we upload some file from local system and displays the output in main panel

3) There is another option where we can save the uploaded file name and path on clicking an action button "Save to Database"

4) Once it is clicked, the file name and path will be stored in two different vectors "tablelist" and "filePath"

5) Once this works fine, we navigate to another tab "View Tables", where there is a dropdown to select tables. This table list would be the vector "tablelist" that would be generated and updated after the action button being clicked.

6) I have tried some code for the same, but it is not working.

Please help. Below is the code

library(shinydashboard)
library(leaflet)
library(ggplot2)
library(DT)
library(openxlsx)

# -----------------------------------------------------------------------------
# Dashboard UI
# -----------------------------------------------------------------------------

dataset <- c("P1-Long-Term-Unemployment-Statistics","P1-OfficeSupplies","P1-SuperStoreUS-2015")
ui <- dashboardPage(
  dashboardHeader(
    title = "Validation Tool"
  ),
  dashboardSidebar(
    sidebarMenu(
      menuItem("Upload File", tabName = "file", icon = icon("database")),
      menuItem("View Tables", tabName = "view", icon = icon("database")),
      menuItem("Append Data", tabName = "append", icon = icon("database")),
      menuItem("Update Table", tabName = "update", icon = icon("crosshairs")),
      menuItem("Construct Table", tabName = "construct", icon = icon("fire"))
    ),

    div(style = "padding-left: 15px;padding-right: 5px; padding-top: 40px;",
        p(class = "small", "Note : This validation tools automates the mainstream process involved in creating a Master data for detailed analysis ")
    )
  ),
  dashboardBody(
    tabItems(
      # Current location ------------------------------------------------------
      tabItem(tabName = "view",
              mainPanel(
                titlePanel(h2("Explore Datasets")),fluidRow(
                  column(6,
                         uiOutput("tables")
                  ),
                  column(6,
                         uiOutput("sheets")
                  )

                ),
        tabsetPanel(type="tab", 
                    tabPanel("Data",br(),div(DT::dataTableOutput("table"),style = "font-size: 100%;width: 150%")                           
                             ),
                    tabPanel("Summary"),
                    tabPanel("Plot")
      )
    )
  ),
  ##################### Tab Item 2 Begins ###########################

  tabItem(tabName = "file",
          mainPanel(
            titlePanel(h2("Upload your XLSX file here ")), fluidRow(
            column(6,
            fileInput('file1', 'Choose a XLSX file to upload',
            accept = c('.xlsx'))),
            column(6,actionButton("save","Save to Database")),
            div(DT::dataTableOutput("contents"),style = "font-size: 100%;width: 150%")
          )

  )
  )
  #####################End of Tab Item 2#############################
)
)
)

# -----------------------------------------------------------------------------
# Dashboard server code
# -----------------------------------------------------------------------------
options(shiny.maxRequestSize = 30*1024^2)

validate_file <- function(input) {
  if (length(input) > 0 & !is.null(input) & input!= "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet") {
    "Please upload a XLSX file"
  } else {
    NULL
  }
}

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

  my_file <- function(){  
  my_file <- paste0("D:/Dataset/",input$table,".xlsx")
  }

  sheetNames <- function(){
  sheetNames <- getSheetNames(my_file())
  }


    output$sheets <- renderUI({
    selectInput("sheet","Sheet:",choices = sheetNames())
    })

    tablelist<-c()

    output$tables <- renderUI({
      selectInput("table","Table:",choices = files)
    })


    output$table <- renderDT(read.xlsx(my_file(),sheet=as.character(input$sheet)),class="display nowrap compact",
                             filter = "top",options = list(
                               scrollX = T,
                               scrollCollapse=TRUE, pageLength=20,scrollY="260px",lengthMenu=c(20,40,60,80,100),
                               search = list(regex = FALSE, caseInsensitive = FALSE)))



    # output$contents <- renderTable({
    #   # input$file1 will be NULL initially. After the user selects
    #   # and uploads a file, it will be a data frame with 'name',
    #   # 'size', 'type', and 'datapath' columns. The 'datapath'
    #   # column will contain the local filenames where the data can
    #   # be found.
    # 
    #   inFile <- input$file1
    #   if (is.null(inFile))
    #     return(NULL)
    #   read.xlsx(inFile$name, sheet=1)
    # })


    ############################## Validate Scenario ########################


    v <- reactive({
      type <- input$file1
      validate(validate_file(type$type))
    })

    ############################# Scenario Ends ############################


    output$contents <- renderDT({
      # input$file1 will be NULL initially. After the user selects
      # and uploads a file, it will be a data frame with 'name',
      # 'size', 'type', and 'datapath' columns. The 'datapath'
      # column will contain the local filenames where the data can
      # be found.
      v()
      inFile <- input$file1
      if (is.null(inFile))
        return(NULL)
      read.xlsx(inFile$datapath, sheet=1)
    },class="display nowrap compact",
                                options = list(
                                  scrollX = T,
                                   pageLength=20,scrollY="340px",lengthMenu=c(20,40,60,80,100)
                                  ))


############################# ACtion Button Save ######################################


    save_result <- function(){
    save_result <- observeEvent(input$save,{

       filenm <- input$file1
       filenm$name

      tablelist <- c(tablelist,as.character(filenm$name))
      filePath <- c(filePath,as.character(filenm$dataPath))
    })
    return (tablelist)
    }
    files <- save_result()



############################# End of Action button ####################################

}

shinyApp(ui, server)

The dropdown "table" is not getting updated/populated now. Please help fixing the issue

How to update dropdown list based on the output of action button in shiny?

Answers (1)

Related Questions