Dynamic UI - Creating observeEvents for Dynamically Created Tables - r

Question

Trying to understand how to create observeEvent()'s to catch changes to an arbitrary number of dynamically-created RHandsontables. Has anyone successfully done this before?
The code below shows creation of the dynamic tables. The comments towards the bottom indicate the inputs I would like to track, but the observeEvents need to account for an arbitrary set of input names.
library(shiny)
library(dplyr)
library(rhandsontable)
library(purrr)
ui <- fluidPage(
uiOutput('tables')
)
server <- function(input, output) {
mtcars$slc <- sample(c('aaa','bbb'),nrow(mtcars),replace=TRUE)
df <- mtcars
getSlice <- function(df_tmp,slca){
print(slca)
df_tmp <- df_tmp %>% filter(slc==slca)
df_tmp
}
output$tables <- renderUI({
slices <- unique(df$slc)
input_dfs <- map(slices,~getSlice(df,.x))
for(i in 1:length(slices)){
local({
i <- i
print(input_dfs[[i]])
output[[slices[i]]] <- renderRHandsontable(rhandsontable(input_dfs[[i]]))
})
}
out <- map(slices,function(x){
rHandsontableOutput(x)
})
print(out)
out
})
### How do I create observeEvents for...
# input$aaa$changes$changes
# input$bbb$changes$changes
# input$arbitrarySlice$changes$changes
}
shinyApp(ui = ui, server = server)

Answer 1

You can iteratively add observeEvents using lapply() as shown:
library(shiny)
library(dplyr)
library(rhandsontable)
library(purrr)
ui <- fluidPage(
uiOutput("tables")
)
server <- function(input, output) {
mtcars$slc <- sample(c("aaa", "bbb"), nrow(mtcars), replace = TRUE)
df <- mtcars
getSlice <- function(df_tmp, slca) {
print(slca)
df_tmp <- df_tmp %>% filter(slc == slca)
df_tmp
}
output$tables <- renderUI({
slices <- unique(df$slc)
input_dfs <- map(slices, ~ getSlice(df, .x))
for (i in 1:length(slices)) {
local({
i <- i
print(input_dfs[[i]])
output[[slices[i]]] <- renderRHandsontable(rhandsontable(input_dfs[[i]]))
})
}
out <- map(slices, function(x) {
rHandsontableOutput(x)
})
print(out)
out
})
### How do I create observeEvents for...
# input$aaa$changes$changes
# input$bbb$changes$changes
# input$arbitrarySlice$changes$changes
### Iteratively add observeEvent()
lapply(unique(df$slc), function(slice) {
observeEvent(input[[slice]]$changes$changes, {
print(paste(slice, "has been updated!"))
print(input[[slice]][["changes"]])
})
})
}
shinyApp(ui = ui, server = server)