MultipartForm annotation collection support

[Nutrymaco]

Should not @MultipartForm support mapping in collection fields? Of course technically it is supported, but with only first InputPart.

I suggest in case where field type is List/Set in MultipartFormAnnotationReader we should do something like this

if (isCollection(fieldType) && providerFor(fieldType) == null) {
    var collectionData = inputParts.stream()
        .map(part -> part.getBody(...))
        .collect();
    setData(collectionData);
} else {
    InputPart part = list.get(0);
    ...
    data = part.getBody(...);
    ...
    setData(data);
}

instead of

InputPart part = list.get(0);
...
data = part.getBody(...);
...
setData(data)

If it is reasonable, i can make PR

[jamezp]

What version of RESTEasy are you using? Also, could you provide a use-case for this? Even just a simple example method. I'm not quite sure I follow.

[Nutrymaco]

Version - 4.7.7.Final (using via Quarkus)
Example:

@POST
@Consumes("multipart/form-data")
public void postForm(@MultipartForm Request request) {

}

class Request {
    @FormParam
    List<Content> content; <-- mapping several files 
}

And we can get several values by one name via MultipartFormDataInput, but can't map several values into one POJO field, because even if we will write custom MessageBodyReader, it will be used only for first inputPart

[jamezp]

In Jakarta REST 3.1 there is a EntityPart which would likely replace this.

That said, 4.7 is no longer be developed. Quarkus itself suggests migrating to RESTEasy Reactive and RESTEasy itself has moved to Jakarta REST 3.1+.

[Nutrymaco]

I undestand, thanks for answering!