From f485c0ffd1ec7976fbb080c33092888fb4485d0c Mon Sep 17 00:00:00 2001
From: Raed Chammam <raed.chammam@algolia.com>
Date: Wed, 5 Nov 2025 13:57:33 +0100
Subject: [PATCH] feat: add fallbackParameters support to FBT

---
 examples/demo/src/routes/ProductPage.tsx             |  3 +++
 examples/js-demo/app.tsx                             |  3 +++
 .../src/getFrequentlyBoughtTogether.ts               | 12 ++++++++++--
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/examples/demo/src/routes/ProductPage.tsx b/examples/demo/src/routes/ProductPage.tsx
index 63a4a589..3bd43392 100644
--- a/examples/demo/src/routes/ProductPage.tsx
+++ b/examples/demo/src/routes/ProductPage.tsx
@@ -103,6 +103,9 @@ export const ProductPage: React.FC = () => {
             ? [`brand:${selectedFacetValue}`]
             : [],
         }}
+        fallbackParameters={{
+          facetFilters: [`brand:${selectedProduct.brand}`],
+        }}
         view={({ itemComponent, items }) => (
           <BundleView
             currentItem={selectedProduct}
diff --git a/examples/js-demo/app.tsx b/examples/js-demo/app.tsx
index 1350bb10..c90eb527 100644
--- a/examples/js-demo/app.tsx
+++ b/examples/js-demo/app.tsx
@@ -239,6 +239,9 @@ function renderRecommendations(selectedProduct: ProductHit) {
       analytics: true,
       clickAnalytics: true,
     },
+    fallbackParameters: {
+      facetFilters: [`brand:${selectedProduct.brand}`],
+    },
     fallbackComponent() {
       return (
         relatedProducts<ProductHit>({
diff --git a/packages/recommend-core/src/getFrequentlyBoughtTogether.ts b/packages/recommend-core/src/getFrequentlyBoughtTogether.ts
index f5a22f9e..fcd4bd18 100644
--- a/packages/recommend-core/src/getFrequentlyBoughtTogether.ts
+++ b/packages/recommend-core/src/getFrequentlyBoughtTogether.ts
@@ -1,4 +1,7 @@
-import { FrequentlyBoughtTogetherQuery } from '@algolia/recommend';
+import {
+  FrequentlyBoughtTogetherQuery,
+  RecommendationsQuery,
+} from '@algolia/recommend';
 
 import { RecommendationsProps } from './getRecommendations';
 import { ProductRecord } from './types';
@@ -10,18 +13,23 @@ import { version } from './version';
 export type GetFrequentlyBoughtTogetherProps<
   TObject
 > = RecommendationsProps<TObject> &
-  Omit<FrequentlyBoughtTogetherQuery, 'objectID'>;
+  Omit<FrequentlyBoughtTogetherQuery, 'objectID'> & {
+    // add fallback parameters manually as it is not supported in @algolia/recommend v4
+    fallbackParameters?: RecommendationsQuery['fallbackParameters'];
+  };
 
 export function getFrequentlyBoughtTogether<TObject>({
   objectIDs,
   recommendClient,
   transformItems = (x) => x,
+  fallbackParameters,
   indexName,
   maxRecommendations,
   queryParameters,
   threshold,
 }: GetFrequentlyBoughtTogetherProps<TObject>) {
   const queries = objectIDs.map((objectID) => ({
+    fallbackParameters,
     indexName,
     maxRecommendations,
     objectID,