README.md

In glin/reactlog: Easier Debugging with the Shiny Reactive Log

reactlog

reactlog extends Shiny with new features that make it easier to debug and trace reactivity, especially in larger apps.

Analyze the reactive log in R

• Print the call stack that caused invalidation (rstudio/shiny#1846)
• List reactive dependencies in a tree structure

Demo

Reactive log visualizer enhancements

• Interactive filtering on selected nodes (rstudio/shiny#1532)
• Jump to the previous/next flush cycle (i.e. all white nodes) (rstudio/shiny#1532)
• Performance improvements

Demo

Installation

# install.packages("devtools")
devtools::install_github("glin/reactlog")

Usage

traceInvalidation()

options(shiny.reactlog = TRUE)

rxA <- reactive({
  input$A
})

observe({
  # call it in a reactive context
  reactlog::traceInvalidation()
  rxA()
})

# or on a reactive expression/observer
reactlog::traceInvalidation(rxA)

listDependencies()

reactive({
  # when multiple dependencies change, it might be useful to see them all
  # not just the one that invalidated the context
  reactlog::listDependencies()
  rxA() + input$A + input$B
})

# also works
reactlog::listDependencies(rxA, invalidated = TRUE)

# when called without a reactive context, shows the entire dependency tree
reactlog::listDependencies()

showReactGraph()

# show the graph for the most recent session
reactlog::showReactGraph()

observe({
  # show the graph filtered on this observer and its dependencies
  reactlog::showReactGraph()
})

API

https://glin.github.io/reactlog/reference/index.html

Caveats

reactlog is experimental and relies on Shiny internals which are subject to change. Use at your own risk, for debugging and development only!

glin/reactlog documentation built on May 29, 2019, 5:58 p.m.