How to invoke decodeData in a header-only request?

[Octopus409]

I am writing a filter that can inject some data into body even it's a header-only request.
I have tried call addDecodedData in decodeHeader() to add some data, but decodeData() has not been called later in the same filter. It seems that this will only take effect in subsequent filters.

I try addDecodeData in decodeHeader() look like this.

if(end_stream){
    // for header-only request, add an empty body frame to trigger decodeData()
    Envoy::Buffer::OwnedImpl buffer{"mark"};
    decoder_callbacks_->addDecodedData(buffer, true);
}
return  Http::FilterHeadersStatus::StopIteration;

I'm not sure if my understanding of addDecodedData is correct. Maybe I should add data in the previous filter and then my custom filter will invoke decodeData? Is there any way to invoke decodeData in the same filter?

[tyxia]

decodeData by design is invoked for body. i.e., not for header only request

[Octopus409]

decodeData by design is invoked for body. i.e., not for header only request

thanks for your comment, you are right, invoke decodeData in a header only request is bit weird.

envoy/envoy/http/filter.h

Line 588 in ee61634

virtual void addDecodedData(Buffer::Instance& data, bool streaming_filter) PURE;

but I found this note in the decoder callback, which seems to support this special requirement.

[tyxia]

That is for subsequent filter not for the same filter