How to set the path to images if they are to be rendered from server side in a golem shiny app? #1137

udurraniAtPresage · 2024-04-08T18:11:03Z

udurraniAtPresage
Apr 8, 2024

I have asked this question on stackoverflow also, but no response for some time now.

Goal

In a shiny app, render multiple ggplot plots with images as facet labels.
You can see the complete source code here.

Details and Problem

I want to create two plots both of which use the same images. In a normal shiny app, I can read the images in global.R and then use them to create plots in the server part.
In the golem framework, I created a R/global.R file with this code:

labels_flowers <- c(
  setosa     = paste0("<img src='", "inst/app/www", "/", "setosa.jpg' width='100'/>"),
  versicolor = paste0("<img src='", "inst/app/www", "/", "versicolor.jpg' width='100'/>"),
  virginica  = paste0("<img src='", "inst/app/www", "/", "virginica.jpg' width='100'/>")
)

And then I used them in two modules.

Module example

Consider this module:

#' plot UI Function
#'
#' @description A shiny Module.
#'
#' @param id,input,output,session Internal parameters for {shiny}.
#'
#' @noRd
#'
#' @import shiny
#' @import ggplot2
#' @import ggtext
mod_plot_ui <- function(id){
  ns <- NS(id)
  tagList(
    plotOutput(ns("myplot"))
  )
}

#' plot Server Functions
#'
#' @noRd
mod_plot_server <- function(id, data){
  moduleServer( id, function(input, output, session){
    ns <- session$ns
    output$myplot <- renderPlot({
      ggplot(data = data()) +
        geom_histogram(aes(Sepal.Length)) +
        facet_wrap(~ Species, labeller = as_labeller(labels_flowers)) +
        theme(strip.text.x = ggtext::element_markdown(size = 20))
    })
  })
}

The app_ui.R and app_server.R use the modules as:

`app_ui.R`

#' The application User-Interface
#'
#' @param request Internal parameter for `{shiny}`.
#'     DO NOT REMOVE.
#' @import shiny
#' @noRd
app_ui <- function(request) {
  tagList(
    # Leave this function for adding external resources
    golem_add_external_resources(),
    # Your application UI logic
    fluidPage(
      h1("example"),
      mod_plot_ui("plot1"),
      mod_plot2_ui("plot2")
    )
  )
}

#' Add external Resources to the Application
#'
#' This function is internally used to add external
#' resources inside the Shiny application.
#'
#' @import shiny
#' @importFrom golem add_resource_path activate_js favicon bundle_resources
#' @noRd
golem_add_external_resources <- function() {
  add_resource_path(
    "www",
    app_sys("app/www")
  )

  tags$head(
    favicon(),
    bundle_resources(
      path = app_sys("app/www"),
      app_title = "example"
    )
    # Add here other external resources
    # for example, you can add shinyalert::useShinyalert()
  )
}

`app_server.R`

#' The application server-side
#'
#' @param input,output,session Internal parameters for {shiny}.
#'     DO NOT REMOVE.
#' @import shiny
#' @import ggplot2
#' @import ggtext
#' @noRd
app_server <- function(input, output, session) {

  df_iris <- reactive(iris)

  mod_plot_server("plot1", df_iris)
  mod_plot2_server("plot2", df_iris)

}