reactiveFileReader

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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).

See Also

reactivePoll

Aliases
  • reactiveFileReader
Examples
## Not run: 
# # Per-session reactive file reader
# function(input, output, session) {
#   fileData <- reactiveFileReader(1000, session, 'data.csv', read.csv)
# 
#   output$data <- renderTable({
#     fileData()
#   })
# }
# 
# # Cross-session reactive file reader. In this example, all sessions share
# # the same reader, so read.csv only gets executed once no matter how many
# # user sessions are connected.
# fileData <- reactiveFileReader(1000, session, 'data.csv', read.csv)
# function(input, output, session) {
#   output$data <- renderTable({
#     fileData()
#   })
# }
# ## End(Not run)
Documentation reproduced from package shiny, version 0.14.2, License: GPL-3 | file LICENSE

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