Save reactive value of selectInput when switching tabs - r

Question

I have a selectInput menu that comes up when I have a certain tab open in my window. I use the same selectInput (inside renderMenu) for multiple tabs. I would like to figure out how to save the value chosen on one tab so it will be the chosen value when switching tabs. Here, for example, if I choose the mtcars plots tab and select 'blue', and then switch to mtcars plots 2, I would like the selected color to be kept at 'blue' rather than switching back to the first option of red.
Yes, I am aware that I am not currently doing anything with the colors, I will add that usage in later.
library(shiny)
library(shinythemes)
library(shinydashboard)
library(tidyverse)
options(warn=-1)
data(iris)
data(mtcars)
# Define UI for application that draws a histogram
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(id = "menume",
sidebarMenuOutput("colormenu"),
menuItem("MTCARS", tabName = "mt", icon = icon("user-tie")),
selectInput("mtvar", "Choose a variable", choices = colnames(mtcars)),
menuItem("IRIS", icon = icon("envelope-open-text"), tabName = "ir"),
selectInput("irvar", "Choose a variable", choices = colnames(iris))
)
),
dashboardBody(
tabItems(
tabItem("mt", uiOutput("mttabs")),
tabItem("ir", uiOutput("irtabs"))
)
)
)
# ui <- secure_app(ui, enable_admin = TRUE)
# Begin Server ----------------------------------------------
server <- function(input, output, session) {
output$colormenu = renderMenu({
req((input$menume=="mt"& input$mtcarstabsall%in%c(2,3))||
(input$menume=="ir"& input$iristabsall%in%c(5,6)))
selectInput("colorme", "Choose a color", c("red", "yellow", "green", "blue", "black"))
})
output$mttabs = renderUI({
output$mtcarsplot1=renderPlot({
ggplot(mtcars, aes_string(x = input$mtvar)) + stat_bin(nbins = 10)
})
output$mtcarsplot2=renderPlot({
ggplot(mtcars, aes_string(x = input$mtvar)) + geom_density()
})
output$mtcarstable1=renderTable({
tabme= head(mtcars, 5)
tabme
})
tabsetPanel(id = "mtcarstabsall",
tabPanel(id = "mttable","MTcars tables",value=1,
fluidRow(box(title = "Table 1", tableOutput("mtcarstable1")))
),
tabPanel(id = "mtplots","mtcars plots",value=2,
fluidRow(box(title = "Plot1", plotOutput("mtcarsplot1"))
)),
tabPanel(id = "mtplots2","mtcars plots 2",value=3,
fluidRow(box(title = "Plot1", plotOutput("mtcarsplot2")))))
})
output$irtabs = renderUI({
output$irisplot1=renderPlot({
ggplot(iris, aes_string(x = input$irvar)) + stat_bin(nbins = 10)
})
output$irisplot2=renderPlot({
ggplot(iris, aes_string(x = input$irvar)) + geom_density()
})
output$iristable1=renderTable({
tabme = head(iris, 5)
tabme
})
tabsetPanel(id = "iristabsall",
tabPanel(id = "mttable","iris tables",value=4,
fluidRow(box(title = "Table 1", tableOutput("iristable1")))
),
tabPanel(id = "irisplots","iris plots",value=5,
fluidRow(box(title = "Plot1", plotOutput("irisplot1"))
)),
tabPanel(id = "irisplots2","iris plots 2",value=6,
fluidRow(box(title = "Plot2", plotOutput("irisplot2"))
)))
})
}
shinyApp(ui, server)

Answer 1

The issue is that the color menu is re-rendering every time you switch tabs and so it resets the selected value. For something like this what you want to do instead is just show/hide the element rather than add/remove it (which is what you're currently doing with req()).
You could use a conditionalPanel in your menu or use the shinyjs package with something like the below (remembering to add shinyjs::useShinyjs() to your ui, to show/hide the color menu:
output$colormenu = renderMenu({
# Remove the req
selectInput("colorme", "Choose a color", c("red", "yellow", "green", "blue", "black"))
})
observe({
# Show/hide menu based on condition using shinyjs::toggle
show_menu_condition <- (input$menume=="mt"& input$mtcarstabsall%in%c(2,3)) || (input$menume=="ir"& input$iristabsall%in%c(5,6))
shinyjs::toggle("colormenu",
condition = show_menu_condition)
})