From ca989918c06c01c416686202ae8c15522f7ffe4f Mon Sep 17 00:00:00 2001
From: Joel Solano <joelsolano@jsolano.de>
Date: Tue, 21 Oct 2025 19:46:29 +0200
Subject: [PATCH 1/2] feat: add repeatArrayParams option

---
 packages/better-fetch/src/types.ts | 7 +++++++
 packages/better-fetch/src/url.ts   | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/packages/better-fetch/src/types.ts b/packages/better-fetch/src/types.ts
index 5d9313f..1130ef0 100644
--- a/packages/better-fetch/src/types.ts
+++ b/packages/better-fetch/src/types.ts
@@ -77,6 +77,13 @@ export type BetterFetchOption<
 			 * Query parameters (key-value pairs)
 			 */
 			query?: Query;
+			/**
+			 * When true, array query parameters are encoded as repeated keys 
+			 * (e.g. `?foo=a&foo=b&foo=c`) instead of JSON (`?foo=["a","b","c"]`).
+			 * 
+			 * @default false - Arrays are encoded as JSON by default.
+			 */
+			repeatArrayParams?: boolean;
 			/**
 			 * Dynamic parameters.
 			 *
diff --git a/packages/better-fetch/src/url.ts b/packages/better-fetch/src/url.ts
index 1f9af3d..de52ea6 100644
--- a/packages/better-fetch/src/url.ts
+++ b/packages/better-fetch/src/url.ts
@@ -32,7 +32,7 @@ export function getURL(url: string, option?: BetterFetchOption) {
 		let serializedValue;
 		if (typeof value === "string") {
 			serializedValue = value;
-		} else if (Array.isArray(value)) {
+		} else if (option?.repeatArrayParams && Array.isArray(value)) {
 			for (const val of value) {
 				queryParams.append(key, val);
 			}

From 6aed98a7e5244a9df932526d96b37d558d9e4eb6 Mon Sep 17 00:00:00 2001
From: Joel Solano <joelsolano@jsolano.de>
Date: Tue, 21 Oct 2025 19:49:11 +0200
Subject: [PATCH 2/2] chore: update tests

---
 packages/better-fetch/src/test/fetch.test.ts | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/packages/better-fetch/src/test/fetch.test.ts b/packages/better-fetch/src/test/fetch.test.ts
index 5bdde68..1c95b4c 100644
--- a/packages/better-fetch/src/test/fetch.test.ts
+++ b/packages/better-fetch/src/test/fetch.test.ts
@@ -566,12 +566,13 @@ describe("url", () => {
 		expect(url.toString()).toBe("http://localhost:4001/param/%23test/item%201");
 	});
 
-	it("should expand array values into multiple query parameters", () => {
+	it("should expand array values into multiple query parameters when repeatArrayParams is true", () => {
 		const url = getURL("/test", {
 			query: {
 				filterValue: ["admin", "user"],
 			},
 			baseURL: "http://localhost:4000",
+			repeatArrayParams: true,
 		});
 
 		expect(url.toString()).toBe(
@@ -579,6 +580,19 @@ describe("url", () => {
 		);
 	});
 
+	it("should preserve arrays as JSON strings", () => {
+		const url = getURL("/test", {
+			query: {
+				filterValue: ["admin", "user"],
+			},
+			baseURL: "http://localhost:4000",
+		});
+
+		expect(url.toString()).toBe(
+			"http://localhost:4000/test?filterValue=%5B%22admin%22%2C%22user%22%5D",
+		);
+	});
+
 	it("should preserve objects as JSON strings", () => {
 		const url = getURL("/test", {
 			query: {