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Data for a component, from the server

Source: R/vue_output.R
render_vue_data.Rd

An output that sends a component's data – some of its fields, by name – rather than markup: the server renders list(mean = 1, sd = 2) and the fields mean and sd of every component following the output take those values; the template redraws what depends on them, and nothing else is touched. It is the declarative twin of update_vue(), with the same rule: a field must be declared in the component's data (or returned by setup()), as Vue tracks only the fields a component starts with; one it does not have is left alone, with a warning in the browser's console. Fields not in a render keep their values.

Usage

render_vue_data(expr, env = parent.frame(), quoted = FALSE)

vue_data_output(outputId)

Arguments

expr

An expression returning the fields: a named list.

env, quoted

As for shiny::renderText().

outputId

The output's id. Only needed to place the output by hand: a component listing it in outputs places it itself.

Value

render_vue_data(), a render function; vue_data_output(), a tag.

Details

The component names the output in its outputs (vue_app(outputs = "stats"), inside a module ns("stats")). It is an output like any other: rendered again when what it reads changes, held back while its component is hidden, an error shown as Shiny shows one, a promise – an ExtendedTask's result – waited for. While it recalculates, $recalculating.<id> is true in the component's templates. It can be cached with shiny::bindCache().

Values travel as vue_app()'s data does: a list an object, a data.frame its rows, JS() a function; I() keeps a vector of one an array.

Where render_vue() draws a component the server writes, this fills one the UI writes: the template stays where it is, the data comes from the server. One output can feed several components, or a vue_store() they all read – shared state, as Vue's guide recommends, with the server as its source. As shinyreact's reactive_output() does for React.

See also

vue_app(), vue_store(), update_vue().

Examples

if (interactive()) {
  library(shiny)
  ui <- fluidPage(
    sliderInput("n", "Draws", 10, 1000, 100),
    vue_app(
      "summary",
      template = htmltools::tags$p(
        `:style` = "{opacity: $recalculating.stats ? 0.5 : 1}",
        "Mean {{ mean }}, sd {{ sd }}"
      ),
      data = list(mean = NA, sd = NA),
      outputs = "stats"
    )
  )
  server <- function(input, output, session) {
    output$stats <- render_vue_data({
      x <- rnorm(input$n)
      list(mean = round(mean(x), 3), sd = round(sd(x), 3))
    })
  }
  shinyApp(ui, server)
}