shiny/R/shinywrappers.R

globalVariables('func')

#' Mark a function as a render function
#'
#' Should be called by implementers of \code{renderXXX} functions in order to
#' mark their return values as Shiny render functions, and to provide a hint to
#' Shiny regarding what UI function is most commonly used with this type of
#' render function. This can be used in R Markdown documents to create complete
#' output widgets out of just the render function.
#'
#' @param uiFunc A function that renders Shiny UI. Must take a single argument:
#'   an output ID.
#' @param renderFunc A function that is suitable for assigning to a Shiny output
#'   slot.
#' @param outputArgs A list of arguments to pass to the \code{uiFunc}. Render
#'   functions should include \code{outputArgs = list()} in their own parameter
#'   list, and pass through the value to \code{markRenderFunction}, to allow
#'   app authors to customize outputs. (Currently, this is only supported for
#'   dynamically generated UIs, such as those created by Shiny code snippets
#'   embedded in R Markdown documents).
#' @return The \code{renderFunc} function, with annotations.
#'
#' @export
markRenderFunction <- function(uiFunc, renderFunc, outputArgs = list()) {
  # a mutable object that keeps track of whether `useRenderFunction` has been
  # executed (this usually only happens when rendering Shiny code snippets in
  # an interactive R Markdown document); its initial value is FALSE
  hasExecuted <- Mutable$new()
  hasExecuted$set(FALSE)

  origRenderFunc <- renderFunc
  renderFunc <- function(...) {
    # if the user provided something through `outputArgs` BUT the
    # `useRenderFunction` was not executed, then outputArgs will be ignored,
    # so throw a warning to let user know the correct usage
    if (length(outputArgs) != 0 && !hasExecuted$get()) {
      warning("Unused argument: outputArgs. The argument outputArgs is only ",
              "meant to be used when embedding snippets of Shiny code in an ",
              "R Markdown code chunk (using runtime: shiny). When running a ",
              "full Shiny app, please set the output arguments directly in ",
              "the corresponding output function of your UI code.")
      # stop warning from happening again for the same object
      hasExecuted$set(TRUE)
    }
    if (is.null(formals(origRenderFunc))) origRenderFunc()
    else origRenderFunc(...)
  }

  structure(renderFunc,
            class       = c("shiny.render.function", "function"),
            outputFunc  = uiFunc,
            outputArgs  = outputArgs,
            hasExecuted = hasExecuted)
}

useRenderFunction <- function(renderFunc, inline = FALSE) {
  outputFunction <- attr(renderFunc, "outputFunc")
  outputArgs <- attr(renderFunc, "outputArgs")
  hasExecuted <- attr(renderFunc, "hasExecuted")
  hasExecuted$set(TRUE)

  for (arg in names(outputArgs)) {
    if (!arg %in% names(formals(outputFunction))) {
      stop(paste0("Unused argument: in 'outputArgs', '",
                  arg, "' is not an valid argument for ",
                  "the output function"))
      outputArgs[[arg]] <- NULL
    }
  }

  id <- createUniqueId(8, "out")
  # Make the id the first positional argument
  outputArgs <- c(list(id), outputArgs)

  o <- getDefaultReactiveDomain()$output
  if (!is.null(o))
    o[[id]] <- renderFunc

  if (is.logical(formals(outputFunction)[["inline"]]) && !("inline" %in% names(outputArgs))) {
    outputArgs[["inline"]] <- inline
  }

  do.call(outputFunction, outputArgs)
}

#' @export
#' @method as.tags shiny.render.function
as.tags.shiny.render.function <- function(x, ..., inline = FALSE) {
  useRenderFunction(x, inline = inline)
}

#' Image file output
#'
#' Renders a reactive image that is suitable for assigning to an \code{output}
#' slot.
#'
#' The expression \code{expr} must return a list containing the attributes for
#' the \code{img} object on the client web page. For the image to display,
#' properly, the list must have at least one entry, \code{src}, which is the
#' path to the image file. It may also useful to have a \code{contentType}
#' entry specifying the MIME type of the image. If one is not provided,
#' \code{renderImage} will try to autodetect the type, based on the file
#' extension.
#'
#' Other elements such as \code{width}, \code{height}, \code{class}, and
#' \code{alt}, can also be added to the list, and they will be used as
#' attributes in the \code{img} object.
#'
#' The corresponding HTML output tag should be \code{div} or \code{img} and have
#' the CSS class name \code{shiny-image-output}.
#'
#' @seealso For more details on how the images are generated, and how to control
#'   the output, see \code{\link{plotPNG}}.
#'
#' @param expr An expression that returns a list.
#' @param env The environment in which to evaluate \code{expr}.
#' @param quoted Is \code{expr} a quoted expression (with \code{quote()})? This
#'   is useful if you want to save an expression in a variable.
#' @param deleteFile Should the file in \code{func()$src} be deleted after
#'   it is sent to the client browser? Generally speaking, if the image is a
#'   temp file generated within \code{func}, then this should be \code{TRUE};
#'   if the image is not a temp file, this should be \code{FALSE}.
#' @param outputArgs A list of arguments to be passed through to the implicit
#'   call to \code{\link{imageOutput}} when \code{renderImage} is used in an
#'   interactive R Markdown document.
#' @export
#'
#' @examples
#' ## Only run examples in interactive R sessions
#' if (interactive()) {
#'
#' ui <- fluidPage(
#'   sliderInput("n", "Number of observations", 2, 1000, 500),
#'   plotOutput("plot1"),
#'   plotOutput("plot2"),
#'   plotOutput("plot3")
#' )
#'
#' server <- function(input, output, session) {
#'
#'   # A plot of fixed size
#'   output$plot1 <- renderImage({
#'     # A temp file to save the output. It will be deleted after renderImage
#'     # sends it, because deleteFile=TRUE.
#'     outfile <- tempfile(fileext='.png')
#'
#'     # Generate a png
#'     png(outfile, width=400, height=400)
#'     hist(rnorm(input$n))
#'     dev.off()
#'
#'     # Return a list
#'     list(src = outfile,
#'          alt = "This is alternate text")
#'   }, deleteFile = TRUE)
#'
#'   # A dynamically-sized plot
#'   output$plot2 <- renderImage({
#'     # Read plot2's width and height. These are reactive values, so this
#'     # expression will re-run whenever these values change.
#'     width  <- session$clientData$output_plot2_width
#'     height <- session$clientData$output_plot2_height
#'
#'     # A temp file to save the output.
#'     outfile <- tempfile(fileext='.png')
#'
#'     png(outfile, width=width, height=height)
#'     hist(rnorm(input$n))
#'     dev.off()
#'
#'     # Return a list containing the filename
#'     list(src = outfile,
#'          width = width,
#'          height = height,
#'          alt = "This is alternate text")
#'   }, deleteFile = TRUE)
#'
#'   # Send a pre-rendered image, and don't delete the image after sending it
#'   # NOTE: For this example to work, it would require files in a subdirectory
#'   # named images/
#'   output$plot3 <- renderImage({
#'     # When input$n is 1, filename is ./images/image1.jpeg
#'     filename <- normalizePath(file.path('./images',
#'                               paste('image', input$n, '.jpeg', sep='')))
#'
#'     # Return a list containing the filename
#'     list(src = filename)
#'   }, deleteFile = FALSE)
#' }
#'
#' shinyApp(ui, server)
#' }
renderImage <- function(expr, env=parent.frame(), quoted=FALSE,
                        deleteFile=TRUE, outputArgs=list()) {
  installExprFunction(expr, "func", env, quoted)

  renderFunc <- function(shinysession, name, ...) {
    imageinfo <- func()
    # Should the file be deleted after being sent? If .deleteFile not set or if
    # TRUE, then delete; otherwise don't delete.
    if (deleteFile) {
      on.exit(unlink(imageinfo$src))
    }

    # If contentType not specified, autodetect based on extension
    contentType <- imageinfo$contentType %OR% getContentType(imageinfo$src)

    # Extra values are everything in imageinfo except 'src' and 'contentType'
    extra_attr <- imageinfo[!names(imageinfo) %in% c('src', 'contentType')]

    # Return a list with src, and other img attributes
    c(src = shinysession$fileUrl(name, file=imageinfo$src, contentType=contentType),
      extra_attr)
  }

  markRenderFunction(imageOutput, renderFunc, outputArgs = outputArgs)
}


#' Printable Output
#'
#' Makes a reactive version of the given function that captures any printed
#' output, and also captures its printable result (unless
#' \code{\link{invisible}}), into a string. The resulting function is suitable
#' for assigning to an  \code{output} slot.
#'
#' The corresponding HTML output tag can be anything (though \code{pre} is
#' recommended if you need a monospace font and whitespace preserved) and should
#' have the CSS class name \code{shiny-text-output}.
#'
#' The result of executing \code{func} will be printed inside a
#' \code{\link[utils]{capture.output}} call.
#'
#' Note that unlike most other Shiny output functions, if the given function
#' returns \code{NULL} then \code{NULL} will actually be visible in the output.
#' To display nothing, make your function return \code{\link{invisible}()}.
#'
#' @param expr An expression that may print output and/or return a printable R
#'   object.
#' @param env The environment in which to evaluate \code{expr}.
#' @param quoted Is \code{expr} a quoted expression (with \code{quote()})? This
#'   is useful if you want to save an expression in a variable.
#' @param width The value for \code{\link{options}('width')}.
#' @param outputArgs A list of arguments to be passed through to the implicit
#'   call to \code{\link{verbatimTextOutput}} when \code{renderPrint} is used
#'   in an interactive R Markdown document.
#' @seealso \code{\link{renderText}} for displaying the value returned from a
#'   function, instead of the printed output.
#'
#' @example res/text-example.R
#'
#' @export
renderPrint <- function(expr, env = parent.frame(), quoted = FALSE,
                        width = getOption('width'), outputArgs=list()) {
  installExprFunction(expr, "func", env, quoted)

  renderFunc <- function(shinysession, name, ...) {
    op <- options(width = width)
    on.exit(options(op), add = TRUE)
    paste(utils::capture.output(func()), collapse = "\n")
  }

  markRenderFunction(verbatimTextOutput, renderFunc, outputArgs = outputArgs)
}

#' Text Output
#'
#' Makes a reactive version of the given function that also uses
#' \code{\link[base]{cat}} to turn its result into a single-element character
#' vector.
#'
#' The corresponding HTML output tag can be anything (though \code{pre} is
#' recommended if you need a monospace font and whitespace preserved) and should
#' have the CSS class name \code{shiny-text-output}.
#'
#' The result of executing \code{func} will passed to \code{cat}, inside a
#' \code{\link[utils]{capture.output}} call.
#'
#' @param expr An expression that returns an R object that can be used as an
#'   argument to \code{cat}.
#' @param env The environment in which to evaluate \code{expr}.
#' @param quoted Is \code{expr} a quoted expression (with \code{quote()})? This
#'   is useful if you want to save an expression in a variable.
#' @param outputArgs A list of arguments to be passed through to the implicit
#'   call to \code{\link{textOutput}} when \code{renderText} is used in an
#'   interactive R Markdown document.
#'
#' @seealso \code{\link{renderPrint}} for capturing the print output of a
#'   function, rather than the returned text value.
#'
#' @example res/text-example.R
#'
#' @export
renderText <- function(expr, env=parent.frame(), quoted=FALSE,
                       outputArgs=list()) {
  installExprFunction(expr, "func", env, quoted)

  renderFunc <- function(shinysession, name, ...) {
    value <- func()
    return(paste(utils::capture.output(cat(value)), collapse="\n"))
  }

  markRenderFunction(textOutput, renderFunc, outputArgs = outputArgs)
}

#' UI Output
#'
#' \bold{Experimental feature.} Makes a reactive version of a function that
#' generates HTML using the Shiny UI library.
#'
#' The corresponding HTML output tag should be \code{div} and have the CSS class
#' name \code{shiny-html-output} (or use \code{\link{uiOutput}}).
#'
#' @param expr An expression that returns a Shiny tag object, \code{\link{HTML}},
#'   or a list of such objects.
#' @param env The environment in which to evaluate \code{expr}.
#' @param quoted Is \code{expr} a quoted expression (with \code{quote()})? This
#'   is useful if you want to save an expression in a variable.
#' @param outputArgs A list of arguments to be passed through to the implicit
#'   call to \code{\link{uiOutput}} when \code{renderUI} is used in an
#'   interactive R Markdown document.
#'
#' @seealso conditionalPanel
#'
#' @export
#' @examples
#' ## Only run examples in interactive R sessions
#' if (interactive()) {
#'
#' ui <- fluidPage(
#'   uiOutput("moreControls")
#' )
#'
#' server <- function(input, output) {
#'   output$moreControls <- renderUI({
#'     tagList(
#'       sliderInput("n", "N", 1, 1000, 500),
#'       textInput("label", "Label")
#'     )
#'   })
#' }
#' shinyApp(ui, server)
#' }
#'
renderUI <- function(expr, env=parent.frame(), quoted=FALSE,
                     outputArgs=list()) {
  installExprFunction(expr, "func", env, quoted)

  renderFunc <- function(shinysession, name, ...) {
    result <- func()
    if (is.null(result) || length(result) == 0)
      return(NULL)

    processDeps(result, shinysession)
  }

  markRenderFunction(uiOutput, renderFunc, outputArgs = outputArgs)
}

#' File Downloads
#'
#' Allows content from the Shiny application to be made available to the user as
#' file downloads (for example, downloading the currently visible data as a CSV
#' file). Both filename and contents can be calculated dynamically at the time
#' the user initiates the download. Assign the return value to a slot on
#' \code{output} in your server function, and in the UI use
#' \code{\link{downloadButton}} or \code{\link{downloadLink}} to make the
#' download available.
#'
#' @param filename A string of the filename, including extension, that the
#'   user's web browser should default to when downloading the file; or a
#'   function that returns such a string. (Reactive values and functions may be
#'   used from this function.)
#' @param content A function that takes a single argument \code{file} that is a
#'   file path (string) of a nonexistent temp file, and writes the content to
#'   that file path. (Reactive values and functions may be used from this
#'   function.)
#' @param contentType A string of the download's
#'   \href{http://en.wikipedia.org/wiki/Internet_media_type}{content type}, for
#'   example \code{"text/csv"} or \code{"image/png"}. If \code{NULL} or
#'   \code{NA}, the content type will be guessed based on the filename
#'   extension, or \code{application/octet-stream} if the extension is unknown.
#' @param outputArgs A list of arguments to be passed through to the implicit
#'   call to \code{\link{downloadButton}} when \code{downloadHandler} is used
#'   in an interactive R Markdown document.
#'
#' @examples
#' ## Only run examples in interactive R sessions
#' if (interactive()) {
#'
#' ui <- fluidPage(
#'   downloadLink("downloadData", "Download")
#' )
#'
#' server <- function(input, output) {
#'   # Our dataset
#'   data <- mtcars
#'
#'   output$downloadData <- downloadHandler(
#'     filename = function() {
#'       paste("data-", Sys.Date(), ".csv", sep="")
#'     },
#'     content = function(file) {
#'       write.csv(data, file)
#'     }
#'   )
#' }
#'
#' shinyApp(ui, server)
#' }
#' @export
downloadHandler <- function(filename, content, contentType=NA, outputArgs=list()) {
  renderFunc <- function(shinysession, name, ...) {
    shinysession$registerDownload(name, filename, contentType, content)
  }
  markRenderFunction(downloadButton, renderFunc, outputArgs = outputArgs)
}

#' Table output with the JavaScript library DataTables
#'
#' Makes a reactive version of the given function that returns a data frame (or
#' matrix), which will be rendered with the DataTables library. Paging,
#' searching, filtering, and sorting can be done on the R side using Shiny as
#' the server infrastructure.
#'
#' For the \code{options} argument, the character elements that have the class
#' \code{"AsIs"} (usually returned from \code{\link{I}()}) will be evaluated in
#' JavaScript. This is useful when the type of the option value is not supported
#' in JSON, e.g., a JavaScript function, which can be obtained by evaluating a
#' character string. Note this only applies to the root-level elements of the
#' options list, and the \code{I()} notation does not work for lower-level
#' elements in the list.
#' @param expr An expression that returns a data frame or a matrix.
#' @param options A list of initialization options to be passed to DataTables,
#'   or a function to return such a list.
#' @param searchDelay The delay for searching, in milliseconds (to avoid too
#'   frequent search requests).
#' @param callback A JavaScript function to be applied to the DataTable object.
#'   This is useful for DataTables plug-ins, which often require the DataTable
#'   instance to be available (\url{http://datatables.net/extensions/}).
#' @param escape Whether to escape HTML entities in the table: \code{TRUE} means
#'   to escape the whole table, and \code{FALSE} means not to escape it.
#'   Alternatively, you can specify numeric column indices or column names to
#'   indicate which columns to escape, e.g. \code{1:5} (the first 5 columns),
#'   \code{c(1, 3, 4)}, or \code{c(-1, -3)} (all columns except the first and
#'   third), or \code{c('Species', 'Sepal.Length')}.
#' @param outputArgs A list of arguments to be passed through to the implicit
#'   call to \code{\link{dataTableOutput}} when \code{renderDataTable} is used
#'   in an interactive R Markdown document.
#'
#' @references \url{http://datatables.net}
#' @note This function only provides the server-side version of DataTables
#'   (using R to process the data object on the server side). There is a
#'   separate package \pkg{DT} (\url{https://github.com/rstudio/DT}) that allows
#'   you to create both server-side and client-side DataTables, and supports
#'   additional DataTables features. Consider using \code{DT::renderDataTable()}
#'   and \code{DT::dataTableOutput()} (see
#'   \url{http://rstudio.github.io/DT/shiny.html} for more information).
#' @export
#' @inheritParams renderPlot
#' @examples
#' ## Only run this example in interactive R sessions
#' if (interactive()) {
#'   # pass a callback function to DataTables using I()
#'   shinyApp(
#'     ui = fluidPage(
#'       fluidRow(
#'         column(12,
#'           dataTableOutput('table')
#'         )
#'       )
#'     ),
#'     server = function(input, output) {
#'       output$table <- renderDataTable(iris,
#'         options = list(
#'           pageLength = 5,
#'           initComplete = I("function(settings, json) {alert('Done.');}")
#'         )
#'       )
#'     }
#'   )
#' }
renderDataTable <- function(expr, options = NULL, searchDelay = 500,
                            callback = 'function(oTable) {}', escape = TRUE,
                            env = parent.frame(), quoted = FALSE,
                            outputArgs=list()) {
  installExprFunction(expr, "func", env, quoted)

  renderFunc <- function(shinysession, name, ...) {
    if (is.function(options)) options <- options()
    options <- checkDT9(options)
    res <- checkAsIs(options)
    data <- func()
    if (length(dim(data)) != 2) return() # expects a rectangular data object
    if (is.data.frame(data)) data <- as.data.frame(data)
    action <- shinysession$registerDataObj(name, data, dataTablesJSON)
    colnames <- colnames(data)
    # if escape is column names, turn names to numeric indices
    if (is.character(escape)) {
      escape <- stats::setNames(seq_len(ncol(data)), colnames)[escape]
      if (any(is.na(escape)))
        stop("Some column names in the 'escape' argument not found in data")
    }
    colnames[escape] <- htmlEscape(colnames[escape])
    if (!is.logical(escape)) {
      if (!is.numeric(escape))
        stop("'escape' must be TRUE, FALSE, or a numeric vector, or column names")
      escape <- paste(escape, collapse = ',')
    }
    list(
      colnames = colnames, action = action, options = res$options,
      evalOptions = if (length(res$eval)) I(res$eval), searchDelay = searchDelay,
      callback = paste(callback, collapse = '\n'), escape = escape
    )
  }

  markRenderFunction(dataTableOutput, renderFunc, outputArgs = outputArgs)
}

# a data frame containing the DataTables 1.9 and 1.10 names
DT10Names <- function() {
  rbind(
    utils::read.table(
      system.file('www/shared/datatables/upgrade1.10.txt', package = 'shiny'),
      stringsAsFactors = FALSE
    ),
    c('aoColumns', 'Removed')  # looks like an omission on the upgrade guide
  )
}

# check DataTables 1.9.x options, and give instructions for upgrading to 1.10.x
checkDT9 <- function(options) {
  nms <- names(options)
  if (length(nms) == 0L) return(options)
  DT10 <- DT10Names()
  # e.g. the top level option name for oLanguage.sSearch should be oLanguage
  i <- nms %in% gsub('[.].*', '', DT10[, 1])
  if (!any(i)) return(options)  # did not see old option names, ready to go!
  msg <- paste(
    'shiny (>= 0.10.2) has upgraded DataTables from 1.9.4 to 1.10.2, ',
    'and DataTables 1.10.x uses different parameter names with 1.9.x. ',
    'Please follow the upgrade guide https://datatables.net/upgrade/1.10-convert',
    ' to change your DataTables parameter names:\n\n',
    paste(utils::formatUL(nms[i]), collapse = '\n'), '\n', sep = ''
  )
  j <- gsub('[.].*', '', DT10[, 1]) %in% nms
  # I cannot help you upgrade automatically in these cases, so I have to stop
  if (any(grepl('[.]', DT10[j, 1])) || any(grepl('[.]', DT10[j, 2]))) stop(msg)
  warning(msg)
  nms10 <- DT10[match(nms[i], DT10[, 1]), 2]
  if (any(nms10 == 'Removed')) stop(
    "These parameters have been removed in DataTables 1.10.x:\n\n",
    paste(utils::formatUL(nms[i][nms10 == 'Removed']), collapse = '\n'),
    "\n\n", msg
  )
  names(options)[i] <- nms10
  options
}

# Deprecated functions ------------------------------------------------------

#' Plot output (deprecated)
#'
#' See \code{\link{renderPlot}}.
#' @param func A function.
#' @param width Width.
#' @param height Height.
#' @param ... Other arguments to pass on.
#' @export
reactivePlot <- function(func, width='auto', height='auto', ...) {
  shinyDeprecated(new="renderPlot")
  renderPlot({ func() }, width=width, height=height, ...)
}

#' Table output (deprecated)
#'
#' See \code{\link{renderTable}}.
#' @param func A function.
#' @param ... Other arguments to pass on.
#' @export
reactiveTable <- function(func, ...) {
  shinyDeprecated(new="renderTable")
  renderTable({ func() })
}

#' Print output (deprecated)
#'
#' See \code{\link{renderPrint}}.
#' @param func A function.
#' @export
reactivePrint <- function(func) {
  shinyDeprecated(new="renderPrint")
  renderPrint({ func() })
}

#' UI output (deprecated)
#'
#' See \code{\link{renderUI}}.
#' @param func A function.
#' @export
reactiveUI <- function(func) {
  shinyDeprecated(new="renderUI")
  renderUI({ func() })
}

#' Text output (deprecated)
#'
#' See \code{\link{renderText}}.
#' @param func A function.
#' @export
reactiveText <- function(func) {
  shinyDeprecated(new="renderText")
  renderText({ func() })
}