Shiny observe() function doesn't work with shinymanager

Question

I have an if statement condition for my plots and I need to use observe function. All the app works OK, but when I try to use the shinymanager for credentials creation, my app doesn't work anymore and the error is always: Error in if: argument has length zero

library(leaflet)
library(leaflet.providers)
library(ggplot2)
library(shinythemes)
library(sf)
library(lubridate)
library(dplyr)
library(rgdal)
library(rgeos)
require(shinymanager)

# Create credentials
credentials <- data.frame(
   user = c("test","manager"), # mandatory
   password = c("654321"), # mandatory
   start = c("2021-05-15","123456"), # optinal (all others)
   expire = c(NA, "2022-12-31"),
   admin = c(FALSE, TRUE),
   comment = "Simple and secure authentification mechanism 
   for single ‘Shiny’ applications.",
   stringsAsFactors = FALSE
 )

# get AOI
download.file(
  "https://github.com/Leprechault/trash/raw/main/stands_example.zip",
  zip_path <- tempfile(fileext = ".zip")
)
unzip(zip_path, exdir = tempdir())

# Open the files
setwd(tempdir())
stands_extent <- readOGR(".", "stands_target") # Border
stands_ds <- read.csv("pred_target_stands.csv", sep=";") # Data set
stands_ds <- stands_ds %>%
  mutate(DATA_S2 = ymd(DATA_S2))
stands_ds$CLASS<-c(rep("A",129),rep("B",130)) 
stands_ds$CD<-abs(rnorm(length(stands_ds[,1]),mean=50))

# Create the shiny dash
ui <- fluidPage(
  theme = shinytheme("cosmo"),
  titlePanel(title="My Map Dashboard"),  
  sidebarLayout(
    sidebarPanel(
      selectInput(inputId = "selectedvariable0",
                  label = "Type", 
                  choices = c(unique(stands_ds$PEST)),selected = TRUE ), 
      selectInput(inputId = "selectedvariable1",
                  label = "Date", 
                  choices = c(unique(stands_ds$DATA_S)),selected = TRUE ), 
      selectInput(inputId = "selectedvariable2",
                  label = "Project", 
                  choices = c(unique(stands_ds$PROJETO)),selected = TRUE ),
      selectInput(inputId = "selectedvariable3",
                  label = "Stand", 
                  choices = c(unique(stands_ds$CD_TALHAO)),selected = TRUE),
      selectInput(inputId = "selectedvariable4",
                  label = "Unique ID", 
                  choices = c(unique(stands_ds$ID_UNIQUE)),selected = TRUE),
      selectInput(inputId = "selectedvariable5",
                  label = "Class", 
                  choices = c(unique(stands_ds$CLASS)),selected = TRUE)            
    ),
    mainPanel(
      textOutput("idSaida"),
      fluidRow(
        splitLayout(plotOutput("myplot"))),
      dateInput(inputId = "Dates selection", label = "Time"),
      leafletOutput("map") 
    )
  )
)
ui <- secure_app(ui)


server <- function(input, output, session){
  
  # # check_credentials returns a function to authenticate users
   res_auth <- secure_server(
     check_credentials = check_credentials(credentials)
   )
  
  
  currentvariable0 <- reactive({input$selectedvariable0})
  currentvariable1 <- reactive({input$selectedvariable1})
  currentvariable2 <- reactive({input$selectedvariable2})
  currentvariable3 <- reactive({input$selectedvariable3})
  currentvariable4 <- reactive({input$selectedvariable4})
  currentvariable5 <- reactive({input$selectedvariable5})
  
  observe({ 
    if(currentvariable5()=="A"){
      
      
      output$myplot <- renderPlot({
        
        #Subset stand
        stands_sel <- subset(stands_extent, stands_extent@data$ID_UNIQUE==currentvariable4())
        
        #Subset for input$var and assign this subset to new object, "fbar"
        ds_sel<- stands_ds[stands_ds$ID_UNIQUE==currentvariable4(),]
        
        #Create a map
        polys <- st_as_sf(stands_sel)
        ggplot() +
          geom_sf(data=polys) +
          geom_point(data=ds_sel,
                     aes(x=X, y=Y), color="red") +
          xlab("Longitude") + ylab("Latitude") +
          coord_sf() +
          theme_bw() +
          theme(text = element_text(size=10)) 
      })
    } else {
      
      #Subset stand
      stands_sel <- subset(stands_extent, stands_extent@data$ID_UNIQUE==currentvariable4())
      
      #Subset for input$var and assign this subset to new object, "fbar"
      ds_sel<- stands_ds[stands_ds$ID_UNIQUE==currentvariable4(),]
      
      #Create a map
      polys <- st_as_sf(stands_sel)
      ggplot() +
        geom_sf(data=polys) +
        geom_raster(data = stands_sel, aes(x = X, y = Y, fill = CD)) + 
        scale_fill_gradientn(name="Desfolha (%)",colours = terrain.colors(100))+
        xlab("Longitude") + ylab("Latitude") +
        coord_sf() +
        theme_bw() +
        theme(text = element_text(size=10)) 
      
    }
    
    output$map <- renderLeaflet({
      
      stands_actual<-stands_ds[stands_ds$ID_UNIQUE==currentvariable4(),]
      lng <- mean(stands_actual$X)
      lat <- mean(stands_actual$Y)
      
      leaflet() %>%
        setView(lng = lng, lat = lat, zoom=17) %>%
        addProviderTiles(providers$Esri.WorldImagery) %>%                   
        addMarkers(lng=stands_actual$X, lat=stands_actual$Y, popup="Location")
      
    }) }) #end of observe function.
}
shinyApp(ui, server)

Please, any help to fix it?

Answer 1

You can add a req check in observe -

observe({ 
    req(currentvariable5())
    if(currentvariable5()=="A"){
    #....
    #....
    #....
    }
})