How to generate multiple plots using modules? - r

Question

I'm trying to create multiple plots using modules, each plot with it's own input. But when I tried to run the app, only the inputs are added each time I add using insertUI and the plot output is blank.
I've tried connecting the ui and the server modules with the same id ("hist1") but it doesn't seem to connect each individual module.
histogramUI <- function(id) {
tagList(
selectInput(NS(id, "var"), "Variable", choices = names(mtcars)),
numericInput(NS(id, "bins"), "bins", value = 10, min = 1),
plotOutput(NS(id, "hist"))
)
}
histogramServer <- function(id) {
moduleServer(id, function(input, output, session) {
data <- reactive(mtcars[[input$var]])
output$hist <- renderPlot({
hist(data(), breaks = input$bins, main = input$var)
}, res = 96)
})
}
ui <- fluidPage(
actionButton("add", "Add"),
div(id = "add_here")
)
server <- function(input, output, session) {
histogramServer("hist1")
observeEvent(input$add, {
insertUI(selector = "#add_here", ui = histogramUI("hist1"))
})
}
shinyApp(ui,server)

Answer 1

Here is a solution where every time you click add you generate a new pair of histogramServer/histogramUI which have the same id (but a different one than the one before, because add gets incremented):
library(shiny)
histogramUI <- function(id) {
tagList(
selectInput(NS(id, "var"), "Variable", choices = names(mtcars)),
numericInput(NS(id, "bins"), "bins", value = 10, min = 1),
plotOutput(NS(id, "hist"))
)
}
histogramServer <- function(id) {
moduleServer(id, function(input, output, session) {
data <- reactive(mtcars[[input$var]])
output$hist <- renderPlot({
hist(data(), breaks = input$bins, main = input$var)
}, res = 96)
})
}
ui <- fluidPage(
actionButton("add", "Add"),
div(id = "add_here")
)
server <- function(input, output, session) {
observeEvent(input$add, {
histogramServer(paste0("hist_", input$add))
insertUI(selector = "#add_here", ui = histogramUI(paste0("hist_", input$add)))
})
}
shinyApp(ui,server)