I'm wondering why global.R doesn't start when i launch my app from Rstudio.
It seems, of what i understood, that global.R must be run once as i launch my app, but instead Rstudio give me an error that it could not find the function that i have defined in the global.R file.
After running global.R by hand with ctl+alt+r then i can launch my app and it recognize the function and works well all during the time i use the R session. I'm not publishing on the web but works just in local.
Do i missed something?
Thanks.
(R version 3.5.2 and shiny 1.2)
The content of global.R is usable only if the shiny app is made of server.R and ui.R. The content of global.R is ignored if the app is made of a unique app.R file.
Splitting your app.R in server.R and ui.R will
resolve your issue.
Since the OP asked about why global.R is not read when the architecture relies only a single app.R, it is because of how the app is started.
If it is started via:
shinyApp(ui = ui, server = server)
Then the application is considering these two functions without running anything beforehand, i.e. neglecting global.R contents. There is, however, the onStart parameter that can be supplied to shinyApp to run something before the app starts, and its description resolves a great deal of confusion:
onStart: A function that will be called before the app is actually run. This is only needed for shinyAppObj, since in the shinyAppDir case, a global.R file can be used for this purpose.
It looks to me that when the application is split into server.R and ui.R, global.R is automatically included by means of running the app through shinyAppDir.
The solutions I found in case one wants to strictly use a single app.R code file and perform some routines prior to starting the app are:
Tinker with onStart parameter inside shinyApp call
Source global.R as #tic-toc-choc points out
Related
I am developing a shiny app which is an exploratory data analysis tool. At this point, I am trying to optimise so that data is loaded in once but is readily available for all users. I am aware of the scoping materials on this i.e. Scoping I have the code to load the data in for the app within a global.R file like so:-
#global.R file
library(feather)
dataframe1<-read_feather("df1.feather")
dataframe2<-read_feather("df2.feather")
These are the dataframes that I need to call once and make available to all users of the app. However, I am calling the ui and the server code all within app.R and I have a hunch that this could be problematic.
I have tried a few implementations as guided by what I have been able to see on the web but it is obvious that I am not doing something properly. Here are some examples of what I have tried
source('global.R', local = T)
ui<-fluidPage({
#code for ui
})
server<-function(input,output,server){
# code for server
}
shinyApp(ui,server)
Where the outcome is this:-
The second thing I have tried is having the global file called in onStart parameter in the shinyApp(), but I have the same error.
The global file is saved in the GitLab repo that I am using to deploy this app on shiny server. The app.R script Can any one show me how I can correctly call the global.R file, so that the data is loaded in once and made available to all users of the app? Do I need to split the app.R file into a ui.R and a server.R file?
Does anyone know i it is possible to change the default file that shiny loads?
I was hoping for a bit more flexibility than one file per directory.
It depends on your setup.
Setup 1: Run app locally from a file
If you want to run an application locally (inside an interactive R session) you can use the command
shiny::shinyAppFile("path/to/my/appFile.R")
to load an application. The app file does not have to be named app.R in that case. Note however that with this approach all relative paths (for example image paths) will be resolved relative to your working directory rather than relative to the app's directory.
Setup 2: Run app on a server
If the app shold be run via shiny-server (or shinyapps.io) things are more complicated. In this case the server will expect the app to be defined either as app.R or ui.R/server.R in order to be loaded properly. The only workaround I am aware of here is to use shinyAppFile inside app.R but this might not be very useful in most situations.
Setup 3: Define the app as an object
You can also define an app as an R object and invoke it by printing the object.
someAppObj <- shinyApp(ui = fluidPage(), server = function(...) {})
## start the app by printing it
someAppObj
As mentioned in the answer of #ismirsehregal, you can also use runApp instead of the printing method which will take care if relative paths and handle the app-environment slightly differently.
runApp(someAppObj)
Setup 1 is actually related to setup 3 since since shinyAppFile returns an app-object.
For a single file app just rename it and add
app <- shinyApp(ui = ui, server = server)
runApp(app)
to be able to source it.
I am now the only responsible for the R shiny Dashboard at work and have got a question.
I know that the ui.R , global.R and Server.R are started automatically from the Server. Now I can see a production.R file, with a function "doSomething()" used in the Server.R file, but the production.R file isn't included or called.
If I move an .R file into the Server Directory, would I be able to access to its functions and variables automatically? In my eyes it has to be so, because everything works fine and the function from the production.R is really used.
Greetings an thanks :-)
Yes, every .R file in the same directory as the ui.R and server.R should be called when running Shiny.
You might have to source the file in your server.R script.
I have 3 files which are needed to my app.
First a general r with functions make some calculations and need to load the ui and server files to run the app.
When I run it on Rstudio it works fine. How is it possible to insert this app to shiny server, meaning that I need first a script and after that run the ui and server files?
Use a global.R file or use source(file, local = FALSE) to read R Code from a file.
For more details check the scoping rules.
I have a shiny app with a bunch of user defined functions and dataframes being passed back and forth between them.
When run from RStudio, it works fine...I can see all the objects in the workspace and everything works just fine. However, when I try to copy and paste the user defined functions in any configuration between the ui.r and server.r files, it complains about not being able to find objects and functions here and there.
What are the best practices for making a shiny app that stands alone, loads external csv files and handles user-defined functions?