\name{downloadHandler}
\alias{downloadHandler}
\title{File Downloads}
\usage{
  downloadHandler(filename, content, contentType = NA)
}
\arguments{
  \item{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.)}

  \item{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.)}

  \item{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.}
}
\description{
  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.
}
\examples{
\dontrun{
# In server.R:
output$downloadData <- downloadHandler(
  filename = function() {
    paste('data-', Sys.Date(), '.csv', sep='')
  },
  content = function(file) {
    write.csv(data, file)
  }
)

# In ui.R:
downloadLink('downloadData', 'Download')
}
}