Add JSON field parser with flexible type transformation

assets/stubs/index.ts

@@ -33,6 +33,41 @@ export const RecordModel = z.object({
 });
 export type RecordModel = z.infer<typeof RecordModel>;
 
+/******* JSON FIELD *******/
+export const pbJsonField = (maxSizeInBytes: number = 1048576) => {
+  const literalSchema = z.union([z.string(), z.number(), z.boolean(), z.null()]);
+  const jsonSchema: z.ZodType<any> = z.lazy(() =>
+    z.union([literalSchema, z.array(jsonSchema), z.record(jsonSchema)])
+  );
+
+  const stringTransform = z.string()
+    .max(maxSizeInBytes, `JSON field cannot exceed ${maxSizeInBytes} bytes`)
+    .transform((val) => {
+      if (val === "true") return true;
+      if (val === "false") return false;
+      if (val === "null") return null;
+
+      if ((val.startsWith('[') && val.endsWith(']'))||(val.startsWith('{') && val.endsWith('}')))
+        try {
+          return JSON.parse(val);
+        } catch {
+          return val;
+        }
+
+      const num = Number(val);
+      if (!isNaN(num) && isFinite(num) && val.trim() !== '')
+        return num;
+
+      if (val.startsWith('"') && val.endsWith('"'))
+        return val.slice(1, -1);
+
+      return val;
+    });
+
+  return z.union([jsonSchema, stringTransform]);
+};
+
+
 /******* RECORDS *******/
 @@_RECORDS_@@