fix(client): Allow browser to set content type of FormData requests

aklinker1 · aklinker1 · commit 8812a29a4cd2 · 2025-12-19T21:52:10.000-06:00
This fixes an issue where the Zeta client was hard coding the content
type without a boundry.
diff --git a/src/client.ts b/src/client.ts
@@ -103,7 +103,7 @@ export function createAppClient<TApp extends App>(
         inputs.body == null ? undefined : smartSerialize(inputs.body);
       if (body) {
         init.body = body.serialized;
-        init.headers["Content-Type"] = body.contentType;
+        if (body.contentType) init.headers["Content-Type"] = body.contentType;
       }
 
       try {
diff --git a/src/internal/serialization.ts b/src/internal/serialization.ts
@@ -1,14 +1,14 @@
 export function smartSerialize(value: unknown):
   | {
-      contentType: string;
+      contentType: string | undefined;
       serialized: BodyInit;
     }
   | undefined {
   if (value == null) return undefined;
 
   if (value instanceof FormData) {
     return {
-      contentType: "multipart/form-data",
+      contentType: undefined, // Let fetch set the content type with a boundary
       serialized: value,
     };
   }

Original file line number	Diff line number	Diff line change
`@@ -103,7 +103,7 @@ export function createAppClient<TApp extends App>(`
`103`	`103`	`inputs.body == null ? undefined : smartSerialize(inputs.body);`
`104`	`104`	`if (body) {`
`105`	`105`	`init.body = body.serialized;`
`106`		`- init.headers["Content-Type"] = body.contentType;`
	`106`	`+ if (body.contentType) init.headers["Content-Type"] = body.contentType;`
`107`	`107`	`}`
`108`	`108`
`109`	`109`	`try {`