Add function to write extension fields to character cards.

public/scripts/extensions.js

@@ -1,6 +1,6 @@
 import { callPopup, eventSource, event_types, saveSettings, saveSettingsDebounced, getRequestHeaders, substituteParams, renderTemplate, animation_duration } from '../script.js';
 import { hideLoader, showLoader } from './loader.js';
-import { isSubsetOf } from './utils.js';
+import { isSubsetOf, setValueByPath } from './utils.js';
 export {
     getContext,
     getApiUrl,
@@ -883,6 +883,55 @@ async function runGenerationInterceptors(chat, contextSize) {
     return aborted;
 }
 
+/**
+ * Writes a field to the character's data extensions object.
+ * @param {number} characterId Index in the character array
+ * @param {string} key Field name
+ * @param {any} value Field value
+ * @returns {Promise<void>} When the field is written
+ */
+export async function writeExtensionField(characterId, key, value) {
+    const context = getContext();
+    const character = context.characters[characterId];
+    if (!character) {
+        console.warn('Character not found', characterId);
+        return;
+    }
+    const path = `data.extensions.${key}`;
+    setValueByPath(character, path, value);
+
+    // Process JSON data
+    if (character.json_data) {
+        const jsonData = JSON.parse(character.json_data);
+        setValueByPath(jsonData, path, value);
+        character.json_data = JSON.stringify(jsonData);
+
+        // Make sure the data doesn't get lost when saving the current character
+        if (Number(characterId) === Number(context.characterId)) {
+            $('#character_json_data').val(character.json_data);
+        }
+    }
+
+    // Save data to the server
+    const saveDataRequest = {
+        avatar: character.avatar,
+        data: {
+            extensions: {
+                [key]: value,
+            },
+        },
+    };
+    const mergeResponse = await fetch('/api/characters/merge-attributes', {
+        method: 'POST',
+        headers: getRequestHeaders(),
+        body: JSON.stringify(saveDataRequest),
+    });
+
+    if (!mergeResponse.ok) {
+        console.error('Failed to save extension field', mergeResponse.statusText);
+    }
+}
+
 jQuery(function () {
     addExtensionsButtonAndMenu();
     $('#extensionsMenuButton').css('display', 'flex');