Hi
This is not a bug, or something like that.
When you use a Processor then its "normal" java code you write there,
so setting a message header, og body or exchange property, then you
set the value as-is, eg its a Object type.
This is by design, as its just normal Java. What you set is what is used.
The underlying code in DefaultMessage / DefaultExchange is also
optimized for these situations to be as fast and low overhead as
possible, especially due to that setting headers is frequently used,
eg a component consumer sets a set of meta-data headers when a new
message is received.
On the other hand when you program in the RouteBuilder, then you
"design" a Camel route (in the configure method). The code there is a
"plan" where you need to use constant / simple / and whatnot to tell
Camel the plan.
In the case of "constant" then that is actually a corner case, as you
could argue that constant(500) can be inferred when doing the "plan"
as 500 is the constant value you want to use.
So suppose if you could say
.setHeader("foo", 500) in the RouteBuilder then Camel could infer that
500 will be a constant. However using constant is not so common in
use, and to make the "plan" consistent, then you need to use an
Expression, just as you would when you use
setHeader("foo", simple( .... ))
Or if you use json-path / xpath
setHeader("foo", xpath("/myroot/mynode@city"))
The problem you hit was that your Processor is anonymous inside the
RouteBuilder so it "inherits" the route builder methods where constant
is available and you mistakenly use that.
If the Processor is not anonymous by a top level class then you could
not do that as it does not extend from RouteBuilder.
On Wed, Aug 25, 2021 at 6:01 PM Karen Lease <[email protected]> wrote:
>
> Hi Onder,
>
> I think we do agree. The one using the processor is the one which calls
> "exchange.getIn().setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500));"
> In that use of setHeader() the constant(500) isn't evaluated.
>
> When I tried it, the one which *is* working is
> >> from("direct:uploadFiles").setHeader(Exchange.HTTP_RESPONSE_CODE,
> constant(500)).
> In that case, the setHeader() is part of the route building and it
> evalutes the constant(500) to an integer.
>
> Karen Lease
>
> On 25/08/2021 17:36, Onder SEZGIN wrote:
> > Thanks Karen investigating further.
> > i am confused though.
> > working version is the one using
> > "exchange.getIn().setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500));"
> > whereas the latter using processor is not working..
> >
> >
> > On Mon, Aug 23, 2021 at 10:09 PM Karen Lease <[email protected]>
> > wrote:
> >
> >> Hi Onder,
> >> I found the explanation for this behavior. It's caused by
> >> "constant(500)" in the expression:
> >> exchange.getIn().setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500));
> >>
> >> The constant expression isn't evaluted to an integer when it is set;
> >> instead it is stored as a ValueBuilder object in the exchange header.
> >> The DefaultHttpBinding class tries to convert the ValueBuilder to an
> >> integer and it doesn't find an appropriate TypeConverter to do this so
> >> it doesn't set a response code.
> >>
> >> If you do: exchange.getIn().setHeader(Exchange.HTTP_RESPONSE_CODE, 500);
> >> it works as you expect.
> >>
> >> In the working version, the constant expression is evaluated by the
> >> setHeader() operation and it stores an integer in the exchange header.
> >>
> >> This is indeed quite confusing!
> >>
> >> Regards,
> >> Karen
> >>
> >> On 19/08/2021 16:04, Onder SEZGIN wrote:
> >>> Even more strange,
> >>>
> >>> i can see 500 in the logs however, response in postman is 404 in this
> >>> example.
> >>>
> >>> from("direct:uploadFiles")
> >>> .process(new Processor() {
> >>> @Override
> >>> public void process(Exchange exchange) throws Exception {
> >>>
> >>> exchange.getIn().setHeader(Exchange.HTTP_RESPONSE_CODE,
> >>> constant(500));
> >>> }
> >>> })
> >>> .log("Response code header: ${in.header.CamelHttpResponseCode}")
> >>> .choice().when(simple("${in.header.CamelHttpResponseCode} == 500"))
> >>> .setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500))
> >>> .otherwise().setHeader(Exchange.HTTP_RESPONSE_CODE, constant(404))
> >>> .end();
> >>>
> >>>
> >>> On Thu, Aug 19, 2021 at 2:51 PM Onder SEZGIN <[email protected]>
> >> wrote:
> >>>
> >>>> Hi,
> >>>>
> >>>> i have a confusing issue while camel 3.7.5.
> >>>>
> >>>> when i have below. i can get 500.(Working fine titled example)
> >>>>
> >>>> However, if i have, HTTP response is not getting set to 500.
> >>>>
> >>>> Can anyone provide any light on this?
> >>>>
> >>>> Thanks.
> >>>>
> >>>> from("direct:uploadFiles")
> >>>> .process(new Processor() {
> >>>> @Override
> >>>> public void process(Exchange exchange) throws Exception {
> >>>>
> >> exchange.getIn().setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500));
> >>>> }
> >>>> });
> >>>>
> >>>>
> >>>> Working fine:
> >>>> ------
> >>>>
> >>>> rest("/endpoint")
> >>>> .consumes("application/json")
> >>>> .produces("application/text")
> >>>> .post("/upload")
> >>>> .type(Void.class)
> >>>> .to("direct:uploadFiles");
> >>>>
> >>>> from("direct:uploadFiles")
> >>>>
> >>>> .setHeader(Exchange.HTTP_RESPONSE_CODE, constant(500))
> >>>>
> >>>>
> >>>
> >>
> >
--
Claus Ibsen
-----------------
http://davsclaus.com @davsclaus
Camel in Action 2: https://www.manning.com/ibsen2
