1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/reactives.R
\name{invalidateLater}
\alias{invalidateLater}
\title{Scheduled Invalidation}
\usage{
invalidateLater(millis, session = getDefaultReactiveDomain())
}
\arguments{
\item{millis}{Approximate milliseconds to wait before invalidating the
current reactive context.}
\item{session}{A session object. This is needed to cancel any scheduled
invalidations after a user has ended the session. If \code{NULL}, then
this invalidation will not be tied to any session, and so it will still
occur.}
}
\description{
Schedules the current reactive context to be invalidated in the given number
of milliseconds.
}
\details{
If this is placed within an observer or reactive expression, that object will
be invalidated (and re-execute) after the interval has passed. The
re-execution will reset the invalidation flag, so in a typical use case, the
object will keep re-executing and waiting for the specified interval. It's
possible to stop this cycle by adding conditional logic that prevents the
\code{invalidateLater} from being run.
}
\examples{
## Only run examples in interactive R sessions
if (interactive()) {
ui <- fluidPage(
sliderInput("n", "Number of observations", 2, 1000, 500),
plotOutput("plot")
)
server <- function(input, output, session) {
observe({
# Re-execute this reactive expression after 1000 milliseconds
invalidateLater(1000, session)
# Do something each time this is invalidated.
# The isolate() makes this observer _not_ get invalidated and re-executed
# when input$n changes.
print(paste("The value of input$n is", isolate(input$n)))
})
# Generate a new histogram at timed intervals, but not when
# input$n changes.
output$plot <- renderPlot({
# Re-execute this reactive expression after 2000 milliseconds
invalidateLater(2000)
hist(rnorm(isolate(input$n)))
})
}
shinyApp(ui, server)
}
}
\seealso{
\code{\link{reactiveTimer}} is a slightly less safe alternative.
}
|
