default to not serializing None options

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

proxmox-api-macro/src/api_macro.rs

@@ -527,7 +527,9 @@ fn handle_struct_named(
         field_ident_list.extend(quote_spanned! { field_span => #field_ident, });
 
         serialize_entries.extend(quote_spanned! { field_span =>
-            state.serialize_field(#field_str, &self.#field_ident)?;
+            if !::proxmox::api::ApiType::should_skip_serialization(&self.#field_ident) {
+                state.serialize_field(#field_str, &self.#field_ident)?;
+            }
         });
 
         field_option_init_list.extend(quote_spanned! { field_span =>

proxmox-api/src/api_type.rs

@@ -185,6 +185,10 @@ pub trait ApiType {
     fn get_type_info(&self) -> &'static TypeInfo {
         Self::type_info()
     }
+
+    fn should_skip_serialization(&self) -> bool {
+        false
+    }
 }
 
 /// Option types are supposed to wrap their underlying types with an `optional:` text in their
@@ -234,6 +238,10 @@ impl<T: ApiType> ApiType for Option<T> {
         unsafe { (*DATA.info.as_ptr()).as_ref().unwrap() }
         */
     }
+
+    fn should_skip_serialization(&self) -> bool {
+        self.is_none()
+    }
 }
 
 /// Any `Result<T, Error>` of course gets the same info as `T`, since this only means that it can