Call a method of an Element component — call

update_el_table() and the other update_el_*() functions assign into the Vue instance's data, which reaches a component's props. Element also documents methods – clearSelection(), setCheckedKeys(), validate() – which are functions on the component and cannot be reached that way. call_el() invokes one: it is call_vue() with Element's references to table rows, upload files and tree nodes.

Usage

call_el(
  session = shiny::getDefaultReactiveDomain(),
  id,
  method,
  args = list(),
  result = TRUE,
  component = NULL
)

Arguments

session: Shiny session; the current one by default, as for shiny::updateTextInput().
id: Component ID (un-namespaced).
method: Name of the Element method to call.
args: A list of arguments, passed positionally. A row of a table or a file of an upload is given by el_table_row() or el_upload_file(): the method needs the object itself.
result: Whether to report the return value as an input. Default TRUE. The input is <id>_<method>; an input of your own with that name – an actionButton("car_next") beside call_el(session, "car", "next") – would hear it too. Give result = FALSE, or another name, then.
component: Optional Element component name ("ElTable") to look for under the component's id. Only needed when a component nests another of its own.

Value

Called for its side effect; returns NULL invisibly.

Details

A method that returns something reports it as input$<id>_<method>, with the method name in snake_case, matching how events are reported: getCheckedKeys arrives as input$<id>_get_checked_keys. The input is set with event priority, so asking twice and getting the same answer still fires an observeEvent() the second time.

A method that returns nothing reports TRUE, so an observeEvent() can still tell that it ran. Pass result = FALSE to send nothing back.

Each component's methods are listed in its own help page, under "Element methods".

Examples

if (interactive()) {
  library(shiny)
  library(shiny.element)

  ui <- el_page(
    el_tree(
      "tree",
      show_checkbox = TRUE,
      node_key = "id",
      checked = "apple",
      default_expand_all = TRUE,
      data = list(list(
        id = "fruit",
        label = "Fruit",
        children = list(
          list(id = "apple", label = "Apple"),
          list(id = "pear", label = "Pear")
        )
      ))
    ),
    el_button("clear", "Clear the ticks"),
    el_button("ask", "Which are ticked?"),
    verbatimTextOutput("answer")
  )

  server <- function(input, output, session) {
    # A command: setCheckedKeys() with an empty set
    observeEvent(input$clear, {
      call_el(session, "tree", "setCheckedKeys", list(list()))
    })

    # A method with a return value answers asynchronously
    observeEvent(input$ask, {
      call_el(session, "tree", "getCheckedKeys")
    })
    output$answer <- renderPrint(input$tree_get_checked_keys)
  }

  shinyApp(ui, server)
}