R Shiny dashboard loading tabs only once - r

Question

I started building my first shiny app but am now struggling with a strange behaviour. First, when I initially load the app, no tab is selected by default. Second, when clicking on any menu on the sidebar it shows the body only on the first time. When I go from "Overview" to "Pivot-Tabelle" and back, the body is blank. What am I missing? Below is the code I used.
library(shiny)
library(shinydashboard)
df<-data.frame(a=c(1,2,3,4),
b=c("A","B","C","D"))
###################Beginn der App################
ui <- dashboardPage(
# Application title
dashboardHeader(),
##----DashboardSidebar----
dashboardSidebar(
menuItem("Overview", tabName = "overview",selected=TRUE),
menuItem("Pivot-Tabelle", tabName = "pivot"),
menuItem("Test", tabName = "farmer")
),
##----DashboardBody----
dashboardBody(
tabItems(
##----TabItem: Overview----
tabItem(tabName="overview",
fluidRow(
valueBoxOutput("A"),
valueBoxOutput("B")
)
),
###----TabItem:Pivot----
tabItem(tabName = "pivot",
##Pivot
column(6,offset=4,titlePanel("Daten-Explorer")),
column(12,
mainPanel(
rpivotTableOutput("pivot")
)
)
),
##----TabItem:Test----
tabItem(tabName = "Test",
h2("In Progress"))
)
)
)
server <- function(input, output) {
##----server:overview----
output$A<-renderValueBox({
valueBox(
paste0(25, "%"), "Landwirte in der Datenbank", icon = icon("Person"),
color = "purple"
)
})
output$B<-renderValueBox({
valueBox(
paste0(55, "%"), "Landwirte in der Datenbank", icon = icon("Person"),
color = "purple"
)
})
##----server:pivot----
output$pivot <- renderRpivotTable({
rpivotTable(data = df)
})
}
# Run the application
shinyApp(ui = ui, server = server)

Answer 1

This seems to work. You need to have sidebarMenu for your menuItems. Also, you need to change tabName to farmer so it matches your menuItem. And I don't think you need mainPanel in there (you can use mainPanel with sidebarPanel as part of a sidebarLayout if you wanted that layout - see layout options). See if this works for you.
library(shiny)
library(shinydashboard)
library(rpivotTable)
df<-data.frame(a=c(1,2,3,4),
b=c("A","B","C","D"))
###################Beginn der App################
ui <- dashboardPage(
# Application title
dashboardHeader(),
##----DashboardSidebar----
dashboardSidebar(
sidebarMenu(
menuItem("Overview", tabName = "overview",selected=TRUE),
menuItem("Pivot-Tabelle", tabName = "pivot"),
menuItem("Test", tabName = "farmer")
)
),
##----DashboardBody----
dashboardBody(
tabItems(
##----TabItem: Overview----
tabItem(tabName="overview",
fluidRow(
valueBoxOutput("A"),
valueBoxOutput("B")
)
),
###----TabItem:Pivot----
tabItem(tabName = "pivot",
##Pivot
column(6,offset=4,titlePanel("Daten-Explorer")),
column(12,
#mainPanel(
rpivotTableOutput("pivot")
#)
)
),
##----TabItem:Test----
tabItem(tabName = "farmer",
h2("In Progress"))
)
)
)
server <- function(input, output) {
##----server:overview----
output$A<-renderValueBox({
valueBox(
paste0(25, "%"), "Landwirte in der Datenbank", icon = icon("Person"),
color = "purple"
)
})
output$B<-renderValueBox({
valueBox(
paste0(55, "%"), "Landwirte in der Datenbank", icon = icon("Person"),
color = "purple"
)
})
##----server:pivot----
output$pivot <- renderRpivotTable({
rpivotTable(data = df)
})
}
# Run the application
shinyApp(ui = ui, server = server)