I've been working on a R Shiny app that uses the content from two folders to perform some analysis and I'm having a hard time working with the reactive expression with the ShinyFiles app.
This is the part that I'm having trouble with:
shinyServer(function(input, output, session) {
volumes = getVolumes()
folderInput1<- reactive({
shinyDirChoose(input, 'directory', roots= volumes, session=session, restrictions=system.file(package='base'))
return(parseDirPath(volumes, input$directory))})
folderInput2<- reactive ({
shinyDirChoose(input, 'directory2', roots=volumes, session=session, restrictions=system.file(package='base'))
return(parseDirPath(volumes, input$directory2 ))})
output$directorypath = renderPrint({folderInput1()})
output$directorypath2 = renderPrint({folderInput2()})
files1 <- list.files(path=folderInput1(), pattern="*.csv", full.names=T)
nFiles1 = length(files1)
files2 <- list.files(path= folderInput2(), pattern="*.csv", full.names=T)
nFiles2 = length(files2)
This is the error message I'm getting: Error in .getReactiveEnvironment()$currentContext() : Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)
When I use the input folder from the user just one time I don't get this error.
THIS PROBLEM WAS SOLVED. Thanks!
Now, I'm having problem while using the reactive expressions in a data structure, like a data frame. For example:
folder_df = data.frame(matrix(0,ncol = 4, nrow = nFiles1()))
I'm getting this error message: Error in matrix(0, ncol = 4, nrow = nFiles1()) : non-numeric matrix extent
You get this error because you try to access reactive values folderInput() and folderInput2() and you do it not within a reactive context as for instance observe, reactive or render* functions.
The solution is to wrap this part of the code (also, files2)
files1 <- list.files(path=folderInput1(), pattern="*.csv", full.names=T)
nFiles1 = length(files1)
into a reactive function. You can then access files1 and nFiles1 within the reactive context via files1() and nfiles1.
files1 <- reactive({
list.files(path = folderInput1(), pattern = "*.csv", full.names = T)
})
nFiles1 <- reactive({ length(files1() ) })
Full example:
library(shiny)
library(shinyFiles)
server <- shinyServer(function(input, output, session) {
volumes = getVolumes()
folderInput1 <- reactive({
shinyDirChoose(input, 'directory', roots = volumes, session = session,
restrictions = system.file(package = 'base'))
return(parseDirPath(volumes, input$directory))
})
folderInput2 <- reactive ({
shinyDirChoose(input, 'directory2', roots = volumes, session = session,
restrictions = system.file(package = 'base'))
return(parseDirPath(volumes, input$directory2))
})
output$directorypath = renderPrint({ folderInput1() })
output$directorypath2 = renderPrint({ folderInput2() })
files1 <- reactive({
list.files(path = folderInput1(), pattern = "*.csv", full.names = T)
})
nFiles1 <- reactive({ length(files1() ) })
files2 <- reactive({
list.files(path = folderInput2(), pattern = "*.csv", full.names = T)
})
nfiles2 <- reactive({ length(files2() )})
})
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
tags$hr(),
shinyDirButton('directory', 'Folder select', 'Please select a folder'),
shinyDirButton('directory2', 'Folder select', 'Please select a folder')
),
mainPanel(
verbatimTextOutput('directorypath'),
verbatimTextOutput('directorypath2')
)
)
)
shinyApp(ui, server)
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