Dependent SelectInput and dataTableOutput in Shiny

Question

I am building a Shiny app & I am stuck. Below is the description of the issue. Any help is much appreciated.

I want to accomplish two things.

1. Have multiple dependent selectInput in my app, which is done!
2. Apart from multiple dependent selectInput, I also have multiple numericInput in the app. So I would like to compile these columns and write as table or dataTable to UI.

Below is a reprex.

library(shiny)
library(shinythemes)

ui <- navbarPage("FET Tracker", theme = shinytheme("flatly"),
                 tabPanel("REARCOM",
                          fluidPage("REARCOM",
                                    sidebarLayout(
                                      sidebarPanel(width = 2,
                                                   dateInput("racomreadingdate", "Meter Reading Date"),
                                                   htmlOutput("RRNo_Selector"),
                                                   numericInput("prevreading", label = "Previous Meter Reading:", value = 1, min = 0),
                                                   numericInput("currreading", label = "Current Meter Reading:", value = 1, min = 0),
                                                   htmlOutput("unitsconsumed"),
                                                   numericInput("amount", "Enter the Amount (INR):", min = 0, value = 0),
                                                   htmlOutput("Location_Selector"),
                                                   htmlOutput("sanctionedHP"),
                                                   htmlOutput("transmission"),
                                                   actionButton("eupdate", label = "Tabulate")
                                                   
                                      ),
                                      mainPanel(dataTableOutput("racomtable"))
                                    )))
                 )

server <- function(input, output, session) {
  racomData <- read.table(
    text = "RRNo    Location    SanctionedHP
RAMEH75 Canteen_01  LT-A
RAMLG2438   Canteen_02  LT-B
RAMLG2941   Canteen_03  LT-C
RAMLG6124   Canteen_04  LT-D
RAMLG6596   Canteen_05  LT-A
RAMP10893   Canteen_06  LT-B
RAMP10894   Canteen_07  LT-C
RAMP12472   Canteen_08  LT-D
RAMP12473   Canteen_09  LT-A
RAMP12474   Canteen_10  LT-B
RAMP15086   Canteen_11  LT-C
RAMP15087   Canteen_12  LT-D
RAMP4646    Canteen_13  LT-A
RAMP4647    Canteen_14  LT-B
RAMP8632    Canteen_15  LT-C
RAMP9223    Canteen_16  LT-D
RAMP9225    Canteen_17  LT-A
RAMP9226    Canteen_18  LT-B
RAMP9825    Canteen_19  LT-C
RAMP9906    Canteen_20  LT-D
RAM12247    Canteen_21  LT-A
RAM4278 Canteen_22  LT-B
RAM4646 Canteen_23  LT-C
RAM4647 Canteen_24  LT-D
RAM4937 Canteen_25  LT-A
RAM5693 Canteen_26  LT-B",
    header = TRUE,
    stringsAsFactors = FALSE)
  
  output$RRNo_Selector <- renderUI({
    
    selectInput(
      inputId = "rrno", 
      label = "Revenue Register No (RR No):",
      choices = as.character(unique(racomData$RRNo)),
      selected = " ")
    
  })
  
  output$Location_Selector <- renderUI({
    
    available <- racomData[racomData$RRNo == input$rrno, "Location"]
    
    selectInput(
      inputId = "location", 
      label = "Location:",
      choices = unique(available),
      selected = unique(available)[1])
    
  })
  
  output$sanctionedHP <- renderUI({
    available2 <- racomData[racomData$Location == input$location, "SanctionedHP"]
    
    selectInput(
      inputId = "sanctionedHP",
      label = "Sanctioned HP:",
      choices = unique(available2),
      selected = unique(available2)[1]
    )
  })
  
  output$unitsconsumed <- renderUI({  
    numericInput("UnitsConsumed","Number of Units Consumed:", value = (input$currreading - input$prevreading))
  })
  
  values <- reactiveValues()
  
  values$df <- data.frame(RRNo = character(),
                          Location = character(),
                          Sanctioned_HP = character(),
                          Reading_Date = character(),
                          Current_Reading = character(),
                          Previous_Reading = character(),
                          Units_Consumed = character(),
                          Amount = character())
  
  observeEvent(input$eupdate, {
    new_row <- data.frame(
      #RRNo = input$RRNo_Selector,
      #Location = input$location,
      #Sanctioned_HP = input$sanctionedHP,
      Reading_Date = strftime(input$racomreadingdate, "%d-%m-%Y"),
      Current_Reading = input$currreading,
      Previous_Reading = input$prevreading,
      #Units_Consumed = input$unitsconsumed,
      Amount = input$amount)
    values$df <- rbind(values$df, new_row)
  })
  
  output$racomtable <- renderDataTable(values$df)
}

shinyApp(ui, server)

The app doesn't work, if the commented lines in observeEvent chunk are uncommented

observeEvent(input$eupdate, {
    new_row <- data.frame(
      #RRNo = input$RRNo_Selector,
      #Location = input$location,
      #Sanctioned_HP = input$sanctionedHP,
      Reading_Date = strftime(input$racomreadingdate, "%d-%m-%Y"),
      Current_Reading = input$currreading,
      Previous_Reading = input$prevreading,
      #Units_Consumed = input$unitsconsumed,
      Amount = input$amount)
    values$df <- rbind(values$df, new_row)
  })

  output$racomtable <- renderDataTable(values$df)
}

Answer 1

You should ensure that you are using the correct inputIDs. Try this

newrow <- eventReactive(input$eupdate, {
    data.frame(
      RRNo = input$rrno,
      Location = input$location,
      Sanctioned_HP = input$sanctionedHP,
      Reading_Date = strftime(input$racomreadingdate, "%d-%m-%Y"),
      Current_Reading = input$currreading,
      Previous_Reading = input$prevreading,
      Units_Consumed = input$UnitsConsumed,
      Amount = input$amount)
    
  })
  
  observeEvent(input$eupdate, {
    values$df <- rbind(values$df, newrow())
  })
  
  output$racomtable <- renderDataTable(values$df)