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#' Insert and remove UI objects
#'
#' These functions allow you to dynamically add and remove arbirary UI
#' into your app, whenever you want, as many times as you want.
#' Unlike [renderUI()], the UI generated with `insertUI()` is persistent:
#' once it's created, it stays there until removed by `removeUI()`. Each
#' new call to `insertUI()` creates more UI objects, in addition to
#' the ones already there (all independent from one another). To
#' update a part of the UI (ex: an input object), you must use the
#' appropriate `render` function or a customized `reactive`
#' function.
#'
#' It's particularly useful to pair `removeUI` with `insertUI()`, but there is
#' no restriction on what you can use on. Any element that can be selected
#' through a jQuery selector can be removed through this function.
#'
#' @param selector A string that is accepted by jQuery's selector
#' (i.e. the string `s` to be placed in a `$(s)` jQuery call).
#'
#' For `insertUI()` this determines the element(s) relative to which you
#' want to insert your UI object. For `removeUI()` this determine the
#' element(s) to be removed. If you want to remove a Shiny input or output,
#' note that many of these are wrapped in `<div>`s, so you may need to use a
#' somewhat complex selector --- see the Examples below. (Alternatively, you
#' could also wrap the inputs/outputs that you want to be able to remove
#' easily in a `<div>` with an id.)
#' @param where Where your UI object should go relative to the selector:
#' \describe{
#' \item{`beforeBegin`}{Before the selector element itself}
#' \item{`afterBegin`}{Just inside the selector element, before its
#' first child}
#' \item{`beforeEnd`}{Just inside the selector element, after its
#' last child (default)}
#' \item{`afterEnd`}{After the selector element itself}
#' }
#' Adapted from <https://developer.mozilla.org/en-US/docs/Web/API/Element/insertAdjacentHTML>.
#' @param ui The UI object you want to insert. This can be anything that
#' you usually put inside your apps's `ui` function. If you're inserting
#' multiple elements in one call, make sure to wrap them in either a
#' `tagList()` or a `tags$div()` (the latter option has the
#' advantage that you can give it an `id` to make it easier to
#' reference or remove it later on). If you want to insert raw html, use
#' `ui = HTML()`.
#' @param multiple In case your selector matches more than one element,
#' `multiple` determines whether Shiny should insert the UI object
#' relative to all matched elements or just relative to the first
#' matched element (default).
#' @param immediate Whether the UI object should be immediately inserted
#' or removed, or whether Shiny should wait until all outputs have been
#' updated and all observers have been run (default).
#' @param session The shiny session. Advanced use only.
#' @examples
#' ## Only run this example in interactive R sessions
#' if (interactive()) {
#' # Define UI
#' ui <- fluidPage(
#' actionButton("add", "Add UI")
#' )
#'
#' # Server logic
#' server <- function(input, output, session) {
#' observeEvent(input$add, {
#' insertUI(
#' selector = "#add",
#' where = "afterEnd",
#' ui = textInput(paste0("txt", input$add),
#' "Insert some text")
#' )
#' })
#' }
#'
#' # Complete app with UI and server components
#' shinyApp(ui, server)
#' }
#'
#' if (interactive()) {
#' # Define UI
#' ui <- fluidPage(
#' actionButton("rmv", "Remove UI"),
#' textInput("txt", "This is no longer useful")
#' )
#'
#' # Server logic
#' server <- function(input, output, session) {
#' observeEvent(input$rmv, {
#' removeUI(
#' selector = "div:has(> #txt)"
#' )
#' })
#' }
#'
#' # Complete app with UI and server components
#' shinyApp(ui, server)
#' }
#' @export
insertUI <- function(selector,
where = c("beforeBegin", "afterBegin", "beforeEnd", "afterEnd"),
ui,
multiple = FALSE,
immediate = FALSE,
session = getDefaultReactiveDomain()) {
force(selector)
force(ui)
force(session)
force(multiple)
if (missing(where)) where <- "beforeEnd"
where <- match.arg(where)
callback <- function() {
session$sendInsertUI(selector = selector,
multiple = multiple,
where = where,
content = processDeps(ui, session))
}
if (!immediate) session$onFlushed(callback, once = TRUE)
else callback()
}
#' @rdname insertUI
#' @export
removeUI <- function(selector,
multiple = FALSE,
immediate = FALSE,
session = getDefaultReactiveDomain()) {
force(selector)
force(multiple)
force(session)
callback <- function() {
session$sendRemoveUI(selector = selector,
multiple = multiple)
}
if (!immediate) session$onFlushed(callback, once = TRUE)
else callback()
}
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