Print the call stack that caused invalidation

Prints the call stack that caused a reactive context to be invalidated. The most recent call is printed first.

traceInvalidation(x = getCurrentContext(), graph = getReactGraph(), n = 1,
  value = TRUE, quiet = FALSE, file = "", append = FALSE)

Arguments

x	A reactive context, expression, observer. Defaults to the current reactive context.
graph	A reactive graph. Defaults to the reactive graph for the current Shiny session.
n	Number of invalidations to trace back. Defaults to 1, the most recent invalidation.
value	If TRUE, show changed values of reactive values.
quiet	If TRUE, suppress output.
file	A filename or connection to print to. Defaults to stdout.
append	If TRUE, output will be appended to file.

Value

A list (stack) of reactive graph nodes.

See also

listDependencies()

Examples

library(shiny)
options(shiny.reactlog = TRUE)

val <- reactiveVal(1, label = "val")

rx <- reactive({
  val()
})

observe({
  traceInvalidation()
  rx()
})

observe(val(10))

# trigger flush event (happens automatically in a Shiny app)
shiny:::flushReact()
#> 4: observe({
#>        traceInvalidation()
#>        rx()
#>    })
#> 3: rx [<text>#7]
#> 2: val =>  num 10
#> 1: observe(val(10)) 

traceInvalidation(rx)
#> 3: rx [<text>#7]
#> 2: val =>  num 10
#> 1: observe(val(10))