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`shiny:conditional` is running multiple times during the flush cycle
System details
Browser Version: Chrome, Version 103.0.5060.114 (Official Build) (64-bit)
Output of sessionInfo()
:
R version 4.1.0 (2021-05-18)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 20.04.2 LTS
Matrix products: default
BLAS: /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3
LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/liblapack.so.3
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 LC_MONETARY=en_US.UTF-8
[6] LC_MESSAGES=en_US.UTF-8 LC_PAPER=en_US.UTF-8 LC_NAME=C LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] shinyGizmo_0.2.2 shiny_1.7.1
loaded via a namespace (and not attached):
[1] Rcpp_1.0.7 knitr_1.36 magrittr_2.0.1 xtable_1.8-4 R6_2.5.1 rlang_1.0.2 fastmap_1.1.0 shinyWidgets_0.7.0
[9] tools_4.1.0 xfun_0.31 cli_3.3.0 jquerylib_0.1.4 htmltools_0.5.2 ellipsis_0.3.2 yaml_2.2.1 digest_0.6.28
[17] lifecycle_1.0.1 purrr_0.3.4 later_1.3.0 sass_0.4.0 promises_1.2.0.1 cachem_1.0.6 glue_1.6.2 evaluate_0.14
[25] mime_0.12 rmarkdown_2.14 compiler_4.1.0 bslib_0.3.1 jsonlite_1.7.2 httpuv_1.6.3
Example application or steps to reproduce the problem
library(shiny)
ui <- fluidPage(
tags$head(
tags$script("$(document).on('shiny:conditional', function(event) {console.log(event);})")
),
actionButton("val", "Value"),
textOutput("out")
)
server <- function(input, output, session) {
output$out <- renderText({
input$val
})
}
shinyApp(ui, server)
Describe the problem in detail
Looking at the browser console we may realize the event is triggered multiple times.
This happens due to the usage of inputConditionals
in multiple places (e.g. while running sendInput
or dispatchMessage
).
A possible solution could be to trigger the function only when the application flush cycle is finished.