feat(collections/search): Improve text index creation and search fallback mechanisms in collections and document search methods

ts/classes.collection.ts

@@ -1,7 +1,7 @@
 import * as plugins from './plugins.js';
 import { SmartdataDb } from './classes.db.js';
 import { SmartdataDbCursor } from './classes.cursor.js';
-import { SmartDataDbDoc, type IIndexOptions } from './classes.doc.js';
+import { SmartDataDbDoc, type IIndexOptions, getSearchableFields } from './classes.doc.js';
 import { SmartdataDbWatcher } from './classes.watcher.js';
 import { CollectionFactory } from './classes.collectionfactory.js';
 
@@ -128,6 +128,8 @@ export class SmartdataCollection<T> {
   public smartdataDb: SmartdataDb;
   public uniqueIndexes: string[] = [];
   public regularIndexes: Array<{field: string, options: IIndexOptions}> = [];
+  // flag to ensure text index is created only once
+  private textIndexCreated: boolean = false;
 
   constructor(classNameArg: string, smartDataDbArg: SmartdataDb) {
     // tell the collection where it belongs
@@ -153,6 +155,14 @@ export class SmartdataCollection<T> {
         console.log(`Successfully initiated Collection ${this.collectionName}`);
       }
       this.mongoDbCollection = this.smartdataDb.mongoDb.collection(this.collectionName);
+      // Auto-create a compound text index on all searchable fields
+      const searchableFields = getSearchableFields(this.collectionName);
+      if (searchableFields.length > 0 && !this.textIndexCreated) {
+        const indexSpec: { [key: string]: string } = {};
+        searchableFields.forEach(f => { indexSpec[f] = 'text'; });
+        await this.mongoDbCollection.createIndex(indexSpec, { name: 'smartdata_text_index' });
+        this.textIndexCreated = true;
+      }
     }
   }