reactiveFileReader: Reactive file reader

Description

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

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).

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.

Examples

Run this code

# 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()
  })
}