FAQ • rhino

Running and deployment

How to run a Rhino application?

You can run a Rhino application exactly the same as a regular Shiny app:

using shiny::runApp()
using the “Run app” button in RStudio

How to automatically reload the application during development?

Call options(shiny.autoreload = TRUE) in your R session. Shiny will monitor the app directory and reload all connected sessions if any changes are detected. More details can be found in Shiny reference.

How to use a specific port when running a Rhino application?

You can:

set port in shiny::runApp, e.g. shiny:runApp(port = 5000)
add options(shiny.port = 5000) to your .Rprofile file

More details can be found in How-to: Set application run parameters.

How to deploy a Rhino application?

The same as in the case of a regular Shiny app, e.g. you can use “Deploy” button in RStudio IDE.

Differences between Rhino and vanilla Shiny

Where are server.R and ui.R files?

Instead of server.R and ui.R, Rhino uses a single file app/main.R. It includes both the server and UI part of the application. The main difference is that both are already Shiny modules so you need to use namespace (ns) in the UI part.

Where is the global.R file?

Rhino encourages you to work with encapsulated modules instead of using global objects, thus it does not include global.R file. Instead, objects are by default only available on the level of a particular script. Depending on the context, objects can be shared explicitly, by being passed as an argument or being exported with @export.

Where should I put library calls?

Rhino application doesn’t use library to load packages. Instead, each script imports its dependencies with box::use:

box::use(
  dplyr, # functions from `dplyr` are available using `$`, e.g. `dplyr$mutate()`
  shiny[div, moduleServer, NS], # `div`, `moduleServer`, and `NS` are available (but other functions from `shiny` are not)
)

The only place where you should use library calls is the dependencies.R file. You can read more about managing R dependencies in this article.

Where is the www directory?

Instead of www, Rhino uses app/static. To utilize it, you need to provide the path to your assets that include static, for example:

img(src = "static/images/appsilon-logo.png")

Common problems

Why doesn’t my input trigger the reactive chain?

Rhino uses Shiny modules to encapsulate the whole application, so the id of every input you create needs to be wrapped in ns, for example:

box::use(
  shiny[NS, textInput],
)

#' @export
ui <- function(id) {
  ns <- NS(id)

  textInput(
    inputId = ns("my_input"),
    label = "My Input"
  )
}

Why is my output not visible?

Rhino uses Shiny modules to encapsulate the whole application, so the id of every output you create needs to be wrapped in ns, for example:

box::use(
  shiny[moduleServer, NS, renderText, textOutput],
)

#' @export
ui <- function(id) {
  ns <- NS(id)

  textOutput(ns("text"))
}

#' @export
server <- function(id) {
  moduleServer(id, function(input, output, session) {
    output$text <- renderText("This is a message!")
  })
}

shinyBS is not working in my Rhino application.

shinyBS uses the .onAttach() hook to call shiny::addResourcePath() which is necessary for its resources (JS and CSS) to be loaded correctly. This hook is never run with box::use() (normally a library() call would run it). It is worth noting that the problem will be also present in vanilla Shiny if you only use :: to access shinyBS functions (shinyBS should use .onLoad() instead).

Workaround: Add the following snippet to your app/main.R (just below the box::use() statements is a good place):

# Run the `.onAttach` hook (shinyBS uses it to add a Shiny resource path).
suppressWarnings(library(shinyBS))

You’ll still need to explicitly box::use() whatever functions you need from shinyBS (library() doesn’t work in a box module).

More details can be found here.

I have an R package installed, but renv::snapshot() didn’t add it to the renv.lock file.

In Rhino, renv only uses packages added to the dependencies.R file. This way you have full control over what libraries are used by your application. Adding library(your package name) to the dependencies.R file should fix the problem.

Check also:

Styling Rhino application

Can I use multiple Sass files?

Yes, you can have any file/directory structure in app/styles that you desire. The app/styles/main.scss is the entry point: you’ll need to @use the other files from main.scss. Then running rhino::build_sass() will be sufficient to include the styles in your application.