Update reactiveVal based on upstream reactive expressions

reactiveVal_example.R

# https://stackoverflow.com/questions/74525623/follow-up-delete-rows-from-data-frames-in-shiny-using-datatable-server-side

library(shiny)
library(DT)

ui <- fluidPage(
  sliderInput(
    inputId = "sl1",
    label = "sl1",
    min = 1,
    max = 10,
    value = c(1,10)
  ),
  sliderInput(
    inputId = "sl2",
    label = "sl2",
    min = 1,
    max = 10,
    value = c(1,10)
  ),
  sliderInput(
    inputId = "sl3",
    label = "sl3",
    min = 1,
    max = 10,
    value = c(1,10)
  ),
  DTOutput("table")
)

server <- function(input, output, session) {
  r1 <- reactive({input$sl1*2})
  r2 <- reactive({input$sl2*3})
  r3 <- reactive({input$sl3*4})
  
  expanded_table <- reactiveVal()
  
  observe({
    expanded_table(expand.grid(r1(), r2(), r3()))
  })
  
  result_table <- reactive({
    expanded_table()*10
  })
  
 output$table <- renderDT({
   result_table()
 }, server = FALSE) 
}

shinyApp(ui, server)