dataType json now handles large payloads.

Author: ciscoheat

CHANGELOG.md

@@ -15,6 +15,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - The rarely used `update` function is removed. Use `form` instead, which now has an option for not tainting the affected fields.
 
+### Fixed
+
+- `dataType: 'json'` now handles large (+1Mb) payloads.
+
 ### Added
 
 - Added `validate` to `superForm`, which can be used to validate any field, at any time.

src/lib/client/index.ts

@@ -1394,7 +1394,11 @@ function formEnhance<T extends AnyZodObject, M>(
           setTimeout(() => validationResponse({ result }), 0);
         } else if (options.dataType === 'json') {
           const postData = get(data);
-          submit.data.set('__superform_json', stringify(postData));
+          const chunks = chunkSubstr(stringify(postData), 500000);
+
+          for (const chunk of chunks) {
+            submit.data.append('__superform_json', chunk);
+          }
 
           // Clear post data to reduce transfer size,
           // since $form should be serialized and sent as json.
@@ -1408,6 +1412,18 @@ function formEnhance<T extends AnyZodObject, M>(
       }
     }
 
+    // Thanks to https://stackoverflow.com/a/29202760/70894
+    function chunkSubstr(str: string, size: number) {
+      const numChunks = Math.ceil(str.length / size);
+      const chunks = new Array(numChunks);
+
+      for (let i = 0, o = 0; i < numChunks; ++i, o += size) {
+        chunks[i] = str.substring(o, o + size);
+      }
+
+      return chunks;
+    }
+
     async function validationResponse(event: ValidationResponse) {
       const result = event.result;
 

src/lib/validate.ts

@@ -299,9 +299,7 @@ export async function superValidate<
     function tryParseSuperJson(data: FormData) {
       if (data.has('__superform_json')) {
         try {
-          const output = parse(
-            data.get('__superform_json')?.toString() ?? ''
-          );
+          const output = parse(data.getAll('__superform_json').join() ?? '');
           if (typeof output === 'object') {
             return output as Record<string, unknown>;
           }