Add ability to update Chat()'s input placeholder

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### New features
 
+* `ui.Chat()` gains a new `.update_user_input()` method, which adds the ability to update the input placeholder message. As a result, `.set_user_message()` is now deprecated (since the new method can also be used to update the message). (#1594)
+
 ### Other changes
 
 ### Bug fixes

js/chat/chat.ts

@@ -27,14 +27,19 @@ type requestScrollEvent = {
   cancelIfScrolledUp: boolean;
 };
 
+type UpdateUserInput = {
+  value?: string;
+  placeholder?: string;
+};
+
 // https://github.com/microsoft/TypeScript/issues/28357#issuecomment-748550734
 declare global {
   interface GlobalEventHandlersEventMap {
     "shiny-chat-input-sent": CustomEvent<Message>;
     "shiny-chat-append-message": CustomEvent<Message>;
     "shiny-chat-append-message-chunk": CustomEvent<Message>;
     "shiny-chat-clear-messages": CustomEvent;
-    "shiny-chat-set-user-input": CustomEvent<string>;
+    "shiny-chat-update-user-input": CustomEvent<UpdateUserInput>;
     "shiny-chat-remove-loading-message": CustomEvent;
     "shiny-chat-request-scroll": CustomEvent<requestScrollEvent>;
   }
@@ -270,7 +275,7 @@ class ChatContainer extends LightElement {
       this.#onAppendChunk
     );
     this.addEventListener("shiny-chat-clear-messages", this.#onClear);
-    this.addEventListener("shiny-chat-set-user-input", this.#onSetUserInput);
+    this.addEventListener("shiny-chat-update-user-input", this.#onUpdateUserInput);
     this.addEventListener(
       "shiny-chat-remove-loading-message",
       this.#onRemoveLoadingMessage
@@ -291,7 +296,10 @@ class ChatContainer extends LightElement {
       this.#onAppendChunk
     );
     this.removeEventListener("shiny-chat-clear-messages", this.#onClear);
-    this.removeEventListener("shiny-chat-set-user-input", this.#onSetUserInput);
+    this.removeEventListener(
+      "shiny-chat-update-user-input",
+      this.#onUpdateUserInput
+    );
     this.removeEventListener(
       "shiny-chat-remove-loading-message",
       this.#onRemoveLoadingMessage
@@ -373,8 +381,14 @@ class ChatContainer extends LightElement {
     this.messages.innerHTML = "";
   }
 
-  #onSetUserInput(event: CustomEvent<string>): void {
-    this.input.setInputValue(event.detail);
+  #onUpdateUserInput(event: CustomEvent<UpdateUserInput>): void {
+    const { value, placeholder } = event.detail;
+    if (value !== undefined) {
+      this.input.setInputValue(value);
+    }
+    if (placeholder !== undefined) {
+      this.input.placeholder = placeholder;
+    }
   }
 
   #onRemoveLoadingMessage(): void {

shiny/ui/_chat.py

@@ -19,6 +19,7 @@
 from htmltools import HTML, Tag, TagAttrValue, css
 
 from .. import _utils, reactive
+from .._deprecated import warn_deprecated
 from .._docstring import add_example
 from .._namespaces import ResolvedId, resolve_id
 from ..session import require_active_session, session_context
@@ -933,27 +934,44 @@ def _user_input(self) -> str:
         id = self.user_input_id
         return cast(str, self._session.input[id]())
 
-    def set_user_message(self, value: str):
+    def update_user_input(
+        self, *, value: str | None = None, placeholder: str | None = None
+    ):
         """
-        Set the user's message.
+        Update the user input.
 
         Parameters
         ----------
         value
             The value to set the user input to.
+        placeholder
+            The placeholder text for the user input.
         """
 
+        obj = _utils.drop_none({"value": value, "placeholder": placeholder})
+
         _utils.run_coro_sync(
             self._session.send_custom_message(
                 "shinyChatMessage",
                 {
                     "id": self.id,
-                    "handler": "shiny-chat-set-user-input",
-                    "obj": value,
+                    "handler": "shiny-chat-update-user-input",
+                    "obj": obj,
                 },
             )
         )
 
+    def set_user_message(self, value: str):
+        """
+        Deprecated. Use `update_user_input(value=value)` instead.
+        """
+
+        warn_deprecated(
+            "set_user_message() is deprecated. Use update_user_input(value=value) instead."
+        )
+
+        self.update_user_input(value=value)
+
     async def clear_messages(self):
         """
         Clear all chat messages.