This is a follow-up for my previous question Automatically reloading shiny app when add changes.
The solution options(shiny.autoreload = TRUE) works perfect when you want to automatically see changes on the browser which you put in the code.
However, the potential problem occurs when you save unfinished/corrupted file. For example, the following ui code lacks a , sign after the titlePanel function:
fluidPage(
titlePanel("Old Faithful Geyser Datass")
sidebarLayout(...
When you save such a file, you will get an error on your browser
ERROR: Error sourcing your_path/ui.R
R console will help detect the problem with the , sign. My impression was that if I improve my code and save the file, it should reload the browser and show my app correctly. Unfortunately, it doesn't do it.
Interesting thing is that an error in the app does not terminate the connection with the browser. To confirm my word, just reload the app manually using reload button in the browser (after improving your code).
Therofore, I examined how this shiny.autoreload option works. As I expected, it checked the time of file modification and then execute reload function. Then reload function send a message via sendMessage to the addMessageHandler:
addMessageHandler('reload', function(message) {
window.location.reload();
});
So it seems that after improving your code the function should be reexecuted, but it's not gonna happen.
To summarise, I think it's not possible to change it without major changes in shiny but maybe I am wrong. Thanks for any suggestion.
PS.You can manipulate example code here to see the problem.
Related
Is it possible to clear the Shiny cache history when reloading an app? Specifically, I have a textInput for adding a title that doesn't clear when the app is restarted. In other words, all of the titles entered into the app on previous runs have been "remembered" and show up in a dropdown list when the app is rerun or restarted again. I have tried using shinyjs::reset, but that clears the current value and not the ones in the "history". I've also tried updateTextInput with an action button set to " ", but also clears only the current value and not the ones in the "history". I have also tried setting ui as a function using:
ui <- function(req) {
fluidPage(...)
}
as well as:
I found that cache of R Shiny server is updated when the date of creation for the file "app.R" is changed.
So, here is the trick I used:
server <- function(input, output, session) {
Trick file date creation update
onStop(function() {
# File name
p <- paste0(getwd(), "/app.R")
# Update file 'date creation'
Sys.setFileTime(p, now())
}) # onStop
} # server
The idea is to update the date of "app.R" creation after each session.
Neither of these solutions worked for me. Finally, I found this post:
I also found this post:
I have been struggling with this problem for quite a while, and thought I had tried everything, including putting a js button on the shiny sidebar to manually refresh (unfortunately that did not work either). There are two things that did work for me:
Make sure all code to read data from files is NOT in a code chunk with a name OTHER THAN global OR
Manually restart the shiny server when new data is uploaded
Obviously the first one is much more manageable, and a solution that I wish I had known weeks ago when I started playing with workarounds.
But I am not sure what is involved in implementing either, so if someone could clarify that, that would be great.
Any help would be much appreciated.
I am writing a vignette for my Shiny application package. At the beginning of my vignette, I source a file called screenshots.R that produces nice screenshots of my application. I am producing them like so:
webshot::appshot(mypackage::run_datepicker_app(),
file = "man/figures/datepicker.png", vwidth = 500, vheight = 200)
This works great and it gives me a great screenshot of what is - in this case - a couple dateInput fields. However, I'd like to be able to get a screenshot of the dateInput in use (say, with the calendar selection exposed).
Is there a way to issue commands to the application object in a script so I can get screenshots of the application in use, rather than having to do it manually?
Have you tried using ShinyDriver from the shinytest package?
You can use shinytest to have a headless browser run the app, interact with it, and take screenshots programmatically. If you don't have phantomJS installed, you'll need to run shinytest::installDependencies() before using ShinyDriver. All you need to do is point it to a directory containing a shiny app (in my case, the folder is 'myApp').
install.packages("shinytest")
shinytest::installDependencies()
app <- shinytest::ShinyDriver$new("myApp")
app$takeScreenshot("screenshot1.png")
button <- app$findElement("#button")
button$click()
Sys.sleep(1)
app$takeScreenshot("screenshot2.png")
app$stop()
I am starting the app in a headless browser, taking a screenshot, finding the button with the id 'button', clicking it, and taking another screenshot, then closing the app. Navigate to specific elements using "#id", where id is just the id you gave the shiny input. You can specify a file path to a png file in the takeScreenshot calls, so that you can then use them in your code elsewhere. Note that you may need to use Sys.sleep to stop the screenshots from being taken before the UI updates.
I have a shiny app that renders an HTML report from an action button. Once this is rendered, a download button shows up in the screen so that the result of that action button can be downloaded. I had to create this two separate buttons because the download handler seems to have a time out, so since my Rmd file takes a bit longer to render, it wouldn't work and it throws an error in the server.
I am currently rendering my Rmd like in the following:
rmarkdown::render(tempReport, output_file = tmp_file,
params = params,
envir = new.env(parent = globalenv()))
The problem is: if one user is rendering his/her report in the server, if a second user clicks the action button to render it at the same time, it will only start rendering once the first user is finished.
Does anyone have any solutions to this?
The behavior you are observing is a result of the fact that R is single-threaded. The direct answer to your issue is that you need to implement asynchronous methods to allow multiple render() processes to run concurrently. More on this at: https://rstudio.github.io/promises/.
If you don't want to go down the asynchronous path and there are a reasonable number of possible report variants, you can pre-render the output and have the user simply open the selected output rather than rendering on-demand.
I'm facing a problem I can't resolve even with options(shiny.trace=TRUE)
It is a webapp that uploads a file and then you click that button to scan() the file you uploaded. When you upload the file all works well. But when you forget uploading the file, the actionButton makes Shiny to abort R, because "R encountered a fatal error".
The output of the debugging function is "RCV {"method":"update","data":{"button:shiny.action":1}} before it aborts.
Before the scan function I write a if(input$button > 0 && !is.null(uploadedFile)) but it stills aborts. (This if statement is within an observe({}) statement.
I've searched around the web but there's nobody who has faced this problem, it seems the problem is within the call of the actionButton... that doesn't manage to do "nothing" when is pressed.
Thank you
Solved: Was a "variable naming" problem. And after finding that, I realized the button wasn't needed in the webapp. Thank you all
Let's take a look at one of the demos.
runExample("09_upload")
I am using the supplied file to perform some computations and to display an aggregated performance across all uploaded files. Therefore, I use something like
tryCatch(compute.smth(), error=function(e){})
so that the displayed result is not affected by the bad input. However, I'd like to indicate somehow that uploading the bad file lead to an error, notifying the user about the problem with his input. It'll be something like
tryCatch(compute.smth(), error=badFile())
where badFile() should modify some displayable output. Any ideas?
As a last resort, this is probably an option, but I'd like some native Shiny.
You can show alerts like below with the ShinySky package: https://github.com/AnalytixWare/ShinySky
You can install the package using
install.packages("devtools")#if not alrady installed
devtools::install_github("ShinySky","AnalytixWare")
Place a shinyalert(id) in the ui.R for where you want the alert to appear.
In your server.R
Make sure you have a 3 parameters funciton being passed to shinyServer e.g.shinyServer(function(input, output,session) {
use showshinyalert(id,HTMLText,session) to show the alert. Clicking on the alert will dismiss it.
See this gist for example https://gist.github.com/xiaodaigh/7707701
Run this too see an example
shinysky::run.shinysky.example()