Add global handlers for all data types

[MoviU]

Q	A
Bug fix?	no
New feature?	yes
Doc updated	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes
License	MIT

Allow custom handlers for all types. ("type" => "*").

[scyzoryck]

Hello.
What would be a usage case for it?

Best, Marcin.

[MoviU]

Hi,

In some cases, the default serialization behavior needs to be customized. For example, in my current use case, if a DTO is marked with a specific attribute (e.g., #[CustomDTO]), I need to apply custom serialization logic—such as inspecting property attributes and executing specific logic when a custom attribute is found.

My current implementation maps a handler to every DTO within a given namespace. This approach relies heavily on Composer’s autoloading and requires cache revalidation whenever changes occur in that namespace (e.g., when a new DTO is created).

Allowing handlers to apply to all types would enable seamless customization of the default serialization process without the need for complex workarounds.

[scyzoryck]

I think adding custom Handler for all classes will create multiple issues - for example with depth exclusions that might not work as expected.
May event system may solve your issues? https://github.com/schmittjoh/serializer/blob/033c9beab9eb708509a3d400e9f0ffeb2d440e71/doc/event_system.rst#serializerpre_serialize
You can change the type to * for any class that needs to handled by your custom Handler.

[MoviU]

The issue I encountered with events during deserialization is that they operate on an already deserialized instance.

If the DTO is readonly, modifying its properties directly isn't possible. Instead, I would need to create a new instance with the updated data.

However, the event system doesn't allow replacing the deserialized result.

Maybe there is another way to achieve this? What do you think?