reactiveFileReader

From shiny v0.12.2 by Winston Chang

Reactive file reader

Given a file path and read function, returns a reactive data source for the contents of the file.

Usage

reactiveFileReader(intervalMillis, session, filePath, readFunc, ...)

Arguments

intervalMillis: Approximate number of milliseconds to wait between checks of the file's last modified time. This can be a numeric value, or a function that returns a numeric value.
session: The user session to associate this file reader with, or NULL if none. If non-null, the reader will automatically stop when the session ends.
filePath: The file path to poll against and to pass to readFunc. This can either be a single-element character vector, or a function that returns one.
readFunc: The function to use to read the file; must expect the first argument to be the file path to read. The return value of this function is used as the value of the reactive file reader.
...: Any additional arguments to pass to readFunc whenever it is invoked.

Details

reactiveFileReader works by periodically checking the file's last modified time; if it has changed, then the file is re-read and any reactive dependents are invalidated.

The intervalMillis, filePath, and readFunc functions will each be executed in a reactive context; therefore, they may read reactive values and reactive expressions.

Value

A reactive expression that returns the contents of the file, and automatically invalidates when the file changes on disk (as determined by last modified time).

Examples

# Per-session reactive file reader
shinyServer(function(input, output, session)) {
  fileData <- reactiveFileReader(1000, session, 'data.csv', read.csv)

  output$data <- renderTable({
    fileData()
  })
}

# Cross-session reactive file reader. In this example, all sessions share
# the same reader, so read.csv only gets executed once no matter how many
# user sessions are connected.
fileData <- reactiveFileReader(1000, session, 'data.csv', read.csv)
shinyServer(function(input, output, session)) {
  output$data <- renderTable({
    fileData()
  })
}

Documentation reproduced from package shiny, version 0.12.2, License: GPL-3 | file LICENSE

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