Support for subcategory backfill (redo)

README.md

@@ -63,7 +63,7 @@ When you install this extension, you'll be able to configure the following param
 
 | Parameter                   | Description                                                                                                                                                                                                                                                                                    |
 |-----------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| Firestore Collection Path   | The Firestore collection that needs to be indexed into Typesense.                                                                                                                                                                                                                              |
+| Firestore Collection Path   | The Firestore collection that needs to be indexed into Typesense. Supports [subcollection wildcards](https://firebase.google.com/docs/functions/firestore-events?gen=2nd#wildcards-parameters) the following way: `users/{userId}/orders` where `{userId}` is a wildcard for all documents in the parent collection.                                                                                                                                                                                                                              |
 | Firestore Collection Fields | A comma separated list of fields that need to be indexed from each Firestore document. Leave blank to index all fields.                                                                                                                                                                        |
 | Flatten Nested Documents    | Should nested documents in Firestore be flattened before they are indexed in Typesense? Set to "Yes" for Typesense Server versions v0.23.1 and below, since indexing Nested objects is natively supported only in Typesense Server v0.24 and above.                                            |
 | Typesense Hosts             | A comma-separated list of Typesense Hosts (only domain without https or port number). For single node clusters, a single hostname is sufficient. For multi-node Highly Available or (Search Delivery Network) SDN Clusters, please be sure to mention all hostnames in a comma-separated list. | 

functions/src/backfill.js

@@ -41,7 +41,16 @@ module.exports = functions.firestore.document(config.typesenseBackfillTriggerDoc
 
   const typesense = createTypesenseClient();
 
-  const querySnapshot = await admin.firestore().collection(config.firestoreCollectionPath);
+  const isSubcollection = config.firestoreCollectionPath.includes("/");
+  let query;
+  if (isSubcollection) {
+    const collectionGroup = config.firestoreCollectionPath.split("/").pop();
+    query = admin.firestore().collectionGroup(collectionGroup);
+  } else {
+    query = admin.firestore().collection(config.firestoreCollectionPath);
+  }
+
+  const querySnapshot = await query;
 
   let lastDoc = null;