Fix behavior for empty arrays and objects in default querySerializer (#1404)

Author: drwpow

Diff for: .changeset/witty-sheep-mix.md

@@ -0,0 +1,5 @@
+---
+"openapi-fetch": patch
+---
+
+Fix behavior for empty arrays and objects in default `querySerializer`

Diff for: packages/openapi-fetch/src/index.ts

@@ -305,7 +305,7 @@ export function defaultQuerySerializer<T = unknown>(q: T): string {
   if (q && typeof q === "object") {
     for (const [k, v] of Object.entries(q)) {
       const value = defaultQueryParamSerializer([k], v);
-      if (value !== undefined) {
+      if (value) {
         search.push(value);
       }
     }
@@ -328,6 +328,9 @@ export function defaultQueryParamSerializer<T = unknown>(
     return `${deepObjectPath(key)}=${String(value)}`;
   }
   if (Array.isArray(value)) {
+    if (!value.length) {
+      return undefined;
+    }
     const nextValue: string[] = [];
     for (const item of value) {
       const next = defaultQueryParamSerializer(key, item);
@@ -338,6 +341,9 @@ export function defaultQueryParamSerializer<T = unknown>(
     return nextValue.join(`&`);
   }
   if (typeof value === "object") {
+    if (!Object.keys(value).length) {
+      return undefined;
+    }
     const nextValue: string[] = [];
     for (const [k, v] of Object.entries(value)) {
       if (v !== undefined && v !== null) {

Diff for: packages/openapi-fetch/test/index.test.ts

@@ -185,6 +185,18 @@ describe("client", () => {
           );
         });
 
+        it("array params (empty)", async () => {
+          const client = createClient<paths>();
+          mockFetchOnce({ status: 200, body: "{}" });
+          await client.GET("/query-params", {
+            params: {
+              query: { array: [] },
+            },
+          });
+
+          expect(fetchMocker.mock.calls[0][0]).toBe("/query-params");
+        });
+
         it("object params", async () => {
           const client = createClient<paths>();
           mockFetchOnce({ status: 200, body: "{}" });

Diff for: packages/openapi-fetch/test/v7-beta.test.ts

@@ -194,6 +194,18 @@ describe("client", () => {
           );
         });
 
+        it("array params (empty)", async () => {
+          const client = createClient<paths>();
+          mockFetchOnce({ status: 200, body: "{}" });
+          await client.GET("/query-params", {
+            params: {
+              query: { array: [] },
+            },
+          });
+
+          expect(fetchMocker.mock.calls[0][0]).toBe("/query-params");
+        });
+
         it("object params", async () => {
           const client = createClient<paths>();
           mockFetchOnce({ status: 200, body: "{}" });