shiny/man/parseShinyInput.Rd

\name{parseShinyInput}
\alias{parseShinyInput}
\title{Provide the new generic for parsing Shiny Input}
\usage{
  parseShinyInput(x, ...)
}
\description{
  Provides an S3 generic to parse incoming Shiny JSON data.
  When defined on a particular class, Shiny will use S3
  dispatch to refine the data passed back from the client
  before making it available in the \code{input} variable
  of the \code{server.R} file.
}
\details{
  The \code{type} of a custom Shiny Input widget will be
  deduced using the \code{getType()} JavaScript function on
  the registered Shiny inputBinding.

  The provided function will be used to parse the data
  delivered from the client before it is available in the
  \code{input} variable. The function will be called with
  the following three parameters: \enumerate{ \item{The
  value of this input as provided by the client,
  deserialized using RJSONIO, then passed through a call to
  \code{\link{structure}} to set the class of the object.
  Note that the call to \code{structure} does convert
  \code{NULL} values to an empty \code{\link{list}}.}
  \item{The \code{shinysession} in which the input exists.}
  \item{The name of the input.} }
}
\examples{
parseShinyInput.myNonNullClass <- function(x, ...){
  # Check for an empty list (the NULL equivalent after setting a class using
  # `structure`).
  ifelse((is.list(val) && length(val) == 0), NA, val)
}
}