Unexpected behavior Select All and Deselect All action buttons (R Shiny) - r

Question

I encountered an unexpected behavior. What I intend to do is:
- when users click "Select All," all rows in "Summary Table" get selected. This WORKS. However, the code below doesn't get called.
data <- eventReactive(input$selectAll,{
print("Select All - restore data")
rawdata
})
- on the other hand, when users click "Deselect All," all rows in "Summary Table" get deselected. This WORKS and the code below GETS called.
# Restore data when users click 'Deselect All'
data <- eventReactive(input$deselectAll,{
print("Deselect All - restore data")
rawdata
})
Any idea why?
Here is my full code:
DATASET
colA <- c('A','B','C','D','E')
colB <- c(1,2,3,4,5)
rawdata <- as.data.frame(cbind(colA,colB))
View(rawdata)
server.R
function(input, output, session) {
# Activate tab 'Result' when users click 'Run'
observeEvent(input$runButton, {
updateTabsetPanel(session, "allResults", 'result')
})
# Create a dataset based on users' selected variables
data <- eventReactive(input$inputVars_rows_selected,{
print("Select Some Vars")
rawdata[, c(input$inputVars_rows_selected)]
})
# Restore data when users click 'Select All'
data <- eventReactive(input$selectAll,{
print("Select All - restore data")
rawdata
})
# Restore data when users click 'Deselect All'
data <- eventReactive(input$deselectAll,{
print("Deselect All - restore data")
rawdata
})
### VARIABLE SELECTION ####
var <- reactiveValues()
# Select all vars
observeEvent(input$selectAll,{
print("SelectAll ObserveEvent")
var$selected <- 1:nrow(rawdata)
print(var$selected)
})
# Deselect all vars
observeEvent(input$deselectAll,{
print("deselectAll ObserveEvent")
var$selected <- 0
print(var$selected)
print(data())
})
### RESULT TAB ###
result <- eventReactive (input$runButton, {
head(data(),2)
})
### RENDERING FUNCTIONS ###
# Default SummaryTable
output$inputVars <- DT::renderDataTable({
if (input$selectAll==0 & input$deselectAll==0) {
print("Default Summary Table")
DT::datatable(rawdata, options = list(paging = FALSE, searching = FALSE))
}
else {
DT::datatable(rawdata, options = list(paging = FALSE, searching = FALSE), selection = list(target = 'row', selected = var$selected))
}
})
# Display results
output$result <- DT::renderDataTable({
DT::datatable(result(), options = list(paging = FALSE, searching = FALSE))
})
output$temp <- renderPrint({
print(input$selectAll)
print(input$deselectAll)
})
}
ui.R
fluidPage(
sidebarPanel(
actionButton("runButton", strong("Run!"))
),
mainPanel(
tabsetPanel(id = "allResults",
tabPanel(value='inputVars',title='Variable Selection',
verticalLayout(
DT::dataTableOutput('inputVars'),
br(),
fluidRow(align="bottom",
column(2, actionButton("selectAll" , strong("Select All"))),
column(3, actionButton("deselectAll", strong("Deselect All")))
)
)
),
tabPanel(value='result',title='Result', DT::dataTableOutput('result')),
tabPanel(value='temp',title="TEMP", verbatimTextOutput("temp"))
)
)
)
UPDATED Server.R #2:
#Mike and #HubertL, I think you are right: the issue is caused by eventReactive having cached values. In this updated version, observeEvent corresponding to Select All and Deselect All work as expected. However, now eventReactive corresponding to input$inputVars_rows_selected NEVER gets called. Any idea why?
function(input, output, session) {
# Activate tab 'Result' when users click 'Run'
observeEvent(input$runButton, {
updateTabsetPanel(session, "allResults", 'result')
})
data <- reactiveValues()
# Create a dataset based on users' selected variables
data <- eventReactive(input$inputVars_rows_selected,{
print("Select Some Vars")
print(input$inputVars_rows_selected)
rawdata[, c(input$inputVars_rows_selected)]
})
### VARIABLE SELECTION ####
var <- reactiveValues()
# Select all vars
observeEvent(input$selectAll,{
print("SelectAll ObserveEvent")
data <- rawdata
var$selected <- 1:nrow(rawdata)
print(var$selected)
print(data)
})
# Deselect all vars
observeEvent(input$deselectAll,{
print("deselectAll ObserveEvent")
data <- rawdata
var$selected <- 0
print(var$selected)
print(data)
})
### RESULT TAB ###
result <- eventReactive (input$runButton, {
head(data(),2)
})
### RENDERING FUNCTIONS ###
# Default SummaryTable
output$inputVars <- DT::renderDataTable({
if (input$selectAll==0 & input$deselectAll==0) {
print("Default Summary Table")
DT::datatable(rawdata, options = list(paging = FALSE, searching = FALSE))
}
else {
DT::datatable(rawdata, options = list(paging = FALSE, searching = FALSE), selection = list(target = 'row', selected = var$selected))
}
})
# Display results
output$result <- DT::renderDataTable({
DT::datatable(result(), options = list(paging = FALSE, searching = FALSE))
})
output$temp <- renderPrint({
print(input$selectAll)
print(input$deselectAll)
print(input$inputVars_rows_selected)
})
}

Answer 1

One reason is because eventReactive is "lazily-evaluated" as opposed to observeEvent which is evaulated immediately.
So in your case the observeEvent corresponding to deselectAll actually uses data(), so that reactiveEvent gets triggered.
# Deselect all vars
observeEvent(input$deselectAll,{
print("deselectAll ObserveEvent")
var$selected <- 0
print(var$selected)
print(data())
})
But the observeEvent corresponding to selectAll does not use data(), so that reactiveEvent does not get triggered:
# Select all vars
observeEvent(input$selectAll,{
print("SelectAll ObserveEvent")
var$selected <- 1:nrow(rawdata)
print(var$selected)
})
I suggest the following changes
If you add a print(data()) here you get some of the behavior you
are seeking.
But it is still not completely right because HubertL's comment that
one definition of data is being overwritten is also valid - and
note that it is not easy to tell where it the data is being pulled.
This is because eventReactive have cached values, so your print
may not show up if a cached value is being used - your code need be
executed to pull that data().
So in any case I would certainly suggest using different names (and
more descriptive) than just repeating "data" to avoid confusion.
Also there is no need to use an eventReactive here, you probably
want a simple reactive. eventReactive is usually needed if you
want to avoid "reactions" from all the other reactive variables in
the code, and I don't see a need for that here.
I would also recommend putting rawdata into a reactiveValues something like this: rv <- reactiveValues(rawdata=rawdata) and then using it as rv$rawdata. This makes it reactive, and then something that uses it will be triggred and recomputed if it ever changes.
See this link (observeEvent vs. eventReactive) for a discussion of the "laziness" of those commands.

Answer 2

Below is the code that works. #Mike and #HubertL were right. The reason is because reactive is lazy vs observeEvent is not. Thanks all for your help!
function(input, output, session) {
# Activate tab 'Result' when users click 'Run'
observeEvent(input$runButton, {
updateTabsetPanel(session, "allResults", 'result')
})
data <- reactive({
print("Select Some Vars")
print(input$inputVars_rows_selected)
rawdata[input$inputVars_rows_selected,]
})
### VARIABLE SELECTION ####
var <- reactiveValues()
# Select all vars
observeEvent(input$selectAll,{
print("SelectAll --- ObserveEvent")
var$selected <- 1:nrow(rawdata)
print(var$selected)
print(input$inputVars_rows_selected)
})
# Deselect all vars
observeEvent(input$deselectAll,{
print("deselectAll --- ObserveEvent")
var$selected <- 0
print(var$selected)
})
### RESULT TAB ###
result <- eventReactive (input$runButton, {
head(data(),5)
})
### RENDERING FUNCTIONS ###
# Default SummaryTable
output$inputVars <- DT::renderDataTable({
if (input$selectAll==0 & input$deselectAll==0) {
print("Default Summary Table")
DT::datatable(rawdata, options = list(paging = FALSE, searching = FALSE))
}
else {
DT::datatable(rawdata, options = list(paging = FALSE, searching = FALSE), selection = list(target = 'row', selected = var$selected))
}
})
# Display results
output$result <- DT::renderDataTable({
DT::datatable(result(), options = list(paging = FALSE, searching = FALSE))
})
output$temp <- renderPrint({
print(input$selectAll)
print(input$deselectAll)
print(input$inputVars_rows_selected)
})
}