Package 'shinychat'

Append an assistant response (or user message) to a chat control

Description

The chat_append function appends a message to an existing chat control. The response can be a string, string generator, string promise, or string promise generator (as returned by the 'elmer' package's chat, stream, chat_async, and stream_async methods, respectively).

This function should be called from a Shiny app's server. It is generally used to append the model's response to the chat, while user messages are added to the chat UI automatically by the front-end. You'd only need to use chat_append(role="user") if you are programmatically generating queries from the server and sending them on behalf of the user, and want them to be reflected in the UI.

Usage

chat_append(
  id,
  response,
  role = c("assistant", "user"),
  session = getDefaultReactiveDomain()
)

Arguments

id	The ID of the chat element
response	The message or message stream to append to the chat element
role	The role of the message (either "assistant" or "user"). Defaults to "assistant".
session	The Shiny session object

Value

Returns a promise. This promise resolves when the message has been successfully sent to the client; note that it does not guarantee that the message was actually received or rendered by the client. The promise rejects if an error occurs while processing the response (see the "Error handling" section).

Error handling

If the response argument is a generator, promise, or promise generator, and an error occurs while producing the message (e.g., an iteration in stream_async fails), the promise returned by chat_append will reject with the error. If the chat_append call is the last expression in a Shiny observer, Shiny will see that the observer failed, and end the user session. If you prefer to handle the error gracefully, use promises::catch() on the promise returned by chat_append.

Examples

library(shiny)
library(coro)
library(bslib)
library(shinychat)

# Dumbest chatbot in the world: ignores user input and chooses
# a random, vague response.
fake_chatbot <- async_generator(function(input) {
  responses <- c(
    "What does that suggest to you?",
    "I see.",
    "I'm not sure I understand you fully.",
    "What do you think?",
    "Can you elaborate on that?",
    "Interesting question! Let's examine thi... **See more**"
  )

  await(async_sleep(1))
  for (chunk in strsplit(sample(responses, 1), "")[[1]]) {
    yield(chunk)
    await(async_sleep(0.02))
  }
})

ui <- page_fillable(
  chat_ui("chat", fill = TRUE)
)

server <- function(input, output, session) {
  observeEvent(input$chat_user_input, {
    response <- fake_chatbot(input$chat_user_input)
    chat_append("chat", response)
  })
}

shinyApp(ui, server)

---

Low-level function to append a message to a chat control

Description

For advanced users who want to control the message chunking behavior. Most users should use chat_append() instead.

Usage

chat_append_message(
  id,
  msg,
  chunk = TRUE,
  operation = c("append", "replace"),
  session = getDefaultReactiveDomain()
)

Arguments

id	The ID of the chat element
msg	The message to append. Should be a named list with role and content fields. The role field should be either "user" or "assistant". The content field should be a string containing the message content, in Markdown format.
chunk	Whether msg is just a chunk of a message, and if so, what type. If FALSE, then msg is a complete message. If "start", then msg is the first chunk of a multi-chunk message. If "end", then msg is the last chunk of a multi-chunk message. If TRUE, then msg is an intermediate chunk of a multi-chunk message. Default is FALSE.
operation	The operation to perform on the message. If "append", then the new content is appended to the existing message content. If "replace", then the existing message content is replaced by the new content. Ignored if chunk is FALSE.
session	The Shiny session object

Value

Returns nothing (invisible(NULL)).

Examples

library(shiny)
library(coro)
library(bslib)
library(shinychat)

# Dumbest chatbot in the world: ignores user input and chooses
# a random, vague response.
fake_chatbot <- async_generator(function(id, input) {
  responses <- c(
    "What does that suggest to you?",
    "I see.",
    "I'm not sure I understand you fully.",
    "What do you think?",
    "Can you elaborate on that?",
    "Interesting question! Let's examine thi... **See more**"
  )

  # Use low-level chat_append_message() to temporarily set a progress message
  chat_append_message(id, list(role = "assistant", content = "_Thinking..._ "))
  await(async_sleep(1))
  # Clear the progress message
  chat_append_message(id, list(role = "assistant", content = ""), operation = "replace")

  for (chunk in strsplit(sample(responses, 1), "")[[1]]) {
    yield(chunk)
    await(async_sleep(0.02))
  }
})

ui <- page_fillable(
  chat_ui("chat", fill = TRUE)
)

server <- function(input, output, session) {
  observeEvent(input$chat_user_input, {
    response <- fake_chatbot("chat", input$chat_user_input)
    chat_append("chat", response)
  })
}

shinyApp(ui, server)

---

Create a chat UI element

Description

Inserts a chat UI element into a Shiny UI, which includes a scrollable section for displaying chat messages, and an input field for the user to enter new messages.

To respond to user input, listen for input$ID_user_input (for example, if id="my_chat", user input will be at input$my_chat_user_input), and use chat_append() to append messages to the chat.

Usage

chat_ui(
  id,
  ...,
  messages = NULL,
  placeholder = "Enter a message...",
  width = "min(680px, 100%)",
  height = "auto",
  fill = TRUE
)

Arguments

id	The ID of the chat element
...	Extra HTML attributes to include on the chat element
messages	A list of messages to prepopulate the chat with. Each message can be a string or a named list with content and role fields.
placeholder	The placeholder text for the chat's user input field
width	The CSS width of the chat element
height	The CSS height of the chat element
fill	Whether the chat element should try to vertically fill its container, if the container is fillable

Value

A Shiny tag object, suitable for inclusion in a Shiny UI

Examples

library(shiny)
library(bslib)
library(shinychat)

ui <- page_fillable(
  chat_ui("chat", fill = TRUE)
)

server <- function(input, output, session) {
  observeEvent(input$chat_user_input, {
    # In a real app, this would call out to a chat model or API,
    # perhaps using the 'elmer' package.
    response <- paste0(
      "You said:\n\n",
      "<blockquote>",
      htmltools::htmlEscape(input$chat_user_input),
      "</blockquote>"
    )
    chat_append("chat", response)
  })
}

shinyApp(ui, server)

---