Can't easily append to a chat_ui() that is dynamically rendered

[cpsievert]

For example, one might expect this to work, but it doesn't

library(shiny)
library(bslib)

ui <- page_fluid(
  uiOutput("x")
)

server <- function(input, output, session) {

  chat_append("chat", "Hello, how can I help you?")

  output$x <- renderUI({
    chat_ui("chat")
  })

}

shinyApp(ui, server)

[jcheng5]

Something feels weird to me about fixing this scenario by delaying all the chat_append actions until after flush. What if chat_ui took an argument for the initial set of messages, would that fix any reasonable scenario?

[cpsievert]

It would definitely help, and probably worth adding regardless of before/after flush. Just curious, are you mainly concerned about the potential for "unresponsive" chats? And/or something else?

[gadenbuie]

TIL I learned that the following works (as in the slider value is 15 after app load) and I would definitely say that it also "feels weird" that it does.

server <- function(input, output, session) {

  updateSliderInput(session, "slider", value = 15)

  output$x <- renderUI({
    sliderInput("slider", "Slider", min = 0, max = 20, value = 0)
  })

}

[jcheng5]

@gadenbuie Feels like a total coincidence that this works; after each flush, the client happens to process all the successful outputs, then all the failed outputs, then all the input updates. I definitely intended all the updateXXXInput commands in a tick to all take effect at once, but I don't think @wch and I ever thought deliberately about whether it ought to happen before or after outputs.