Question about @Part binding

[nanodeath]

[This might be a question primarily for the maintainers]

I'm trying to get the @Part annotation (and multipart uploads in general) working for the micronaut-aws module and the ApiGatewayServletRequest. One of the problems is that when you do a multipart upload that contains a file, it tries to coerce that into a string. Not great, but that part is fixed in my local, at least.

However, while it's not throwing anymore, all of my @Part bindings are coming through as null. I see we have a PartAnnotationBinder, but it seems like a deliberate no-op and says "should be handled by a multipart processor".

micronaut-core/http/src/main/java/io/micronaut/http/bind/binders/PartAnnotationBinder.java

Lines 32 to 34 in d3b0c38

	public BindingResult<T> bind(ArgumentConversionContext<T> context, HttpRequest<?> source) {
	return BindingResult.unsatisfied();
	}

Well...whatever multipart processor is supposed to be handling this on the ApiGatewayServletRequest side is not handling it 🙂 I was looking for help with what it's supposed to be doing and where, and how it's handled on the non-AWS side of things and perhaps I can replicate that.

[yawkat]

Sorry, multipart is not supported by micronaut-aws, and not by the aws lambda java library from what I can tell

[nanodeath]

It works just fine in Serverless Function mode provided I parse the body myself; why wouldn't it? I'm trying to get information on how Micronaut without AWS integration handles it.

Also I'd appreciate it if you didn't close the discussion immediately without elaborating.

[nanodeath]

To answer my own question, it looks like this is not directly in Micronaut Core, but in http-server-netty (which is...a part of the Micronaut Core repo I suppose).

The main class that handles @Part is

micronaut-core/http-server-netty/src/main/java/io/micronaut/http/server/netty/binders/NettyPartUploadAnnotationBinder.java

Line 44 in d3b0c38

final class NettyPartUploadAnnotationBinder<T> implements AnnotatedRequestArgumentBinder<Part, T>, RequestArgumentBinder<T> {

which delegates to another class for CompletedFileUpload specifically

micronaut-core/http-server-netty/src/main/java/io/micronaut/http/server/netty/binders/NettyCompletedFileUploadBinder.java

Line 41 in d3b0c38

final class NettyCompletedFileUploadBinder implements TypedRequestArgumentBinder<CompletedFileUpload>, NettyRequestArgumentBinder<CompletedFileUpload> {