How shall I define a declarative HttpClient for a REST service with an operation taking a multi-valued query parameter?

[nedelva]

I have defined this declarative client:

@Client("${micronaut.http.services.my-api.url}")
public interface ContractsApi {
    @Get("/auto")
    @Consumes
    @Produces
    public List<Contracts> listContracts(@Nullable @QueryValue("Enterprise_Nbr") String enterpriseNbr,
                               @QueryValue("producers") @Format("csv") @Nullable List<String> producers);
}

All fine and dandy until a want to use the multi-valued query parameter producers.
My issue here is that when passing a list of producers the generated URI looks like
/auto?Enterprise_Nbr=1234&producers=111%2C222%2C333

What the server expects is instead
/auto?Enterprise_Nbr=1234&producers=111,222,333
According to the user's guide (section 7.5.1 Customizing Parameter Binding), I should be able to use the Format annotation together with QueryValue to specify how the query values are to be formatted.

(I also tried to pass producers as a single String value by joining the values with comma delimiter, but the comma is escaped to %2C prior to the call)

[nedelva]

Not any Micronaut gurus out there willing to answer? If it cannot be achieved with the declarative client at least give me an alternative..
Passing an list of values in a query parameter seem such a basic feature, I don't believe it is not supported.

[graemerocher]

This is documented here https://docs.micronaut.io/latest/guide/#clientParameters

[nedelva]

Yes, Graeme, thanks for pointing that out. The section 7.5.1 I cited comes from that same location. Here's the relevant bit (and I quote):

The Format annotation can be used together with @QueryValue annotation to format query values.

The supported values are: "csv", "ssv", "pipes", "multi" and "deep-object", where the meaning is similar to Open API v3 query parameter’s style attribute.

The format can only be applied to java.lang.Iterable, java.util.Map or POJO with Introspected annotation. Examples of how different values will be formatted are given in the table below:

Format	Iterable example	Map or POJO example
Original value	["Mike", "Adam", "Kate"]	{"name": "Mike", "age": 30"}
"CSV"	"param=Mike,Adam,Kate"	"param=name,Mike,age,30"
"SSV"	"param=Mike Adam Kate"	"param=name Mike age 30"
"PIPES"	"param=Mike|Adam|Kate"	"param=name|Mike|age|30"
"MULTI"	"param=Mike&param=Adam&param=Kate"	"name=Mike&age=30"
"DEEP_OBJECT"	"param[0]=Mike&param[1]=Adam&param[2]=Kate"	"param[name]=Mike&param[age]=30"

However, the generated URI contains encoded commas (as I already mentioned in my first post) and I don't want that. The annotation @Format("csv") does not have any effect in this particular setup.

[graemerocher]

Perhaps

micronaut-core/http-client/src/test/groovy/io/micronaut/http/client/format/ClientFormatSpec.groovy

Line 20 in b106b5a

class ClientFormatSpec extends Specification {

can shed some more light

[nedelva]

After some digging in the http-client codebase I ended up writing my own JUnit 5 version of the ClientFormatSpec (which ALSO passed all the tests, yay!).

Thing is, after setting up the logging level to DEBUG for http-client:
<logger name="io.micronaut.http.client" level="debug" />

I could see this output from running the tests:

09:39:55.971 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=name%7CMark%7Cage%7C30
09:39:56.000 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=tree%7Cspruce%7Cseed
09:39:56.010 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param%5B0%5D=a&param%5B1%5D=b&param%5B2%5D=c%2Cd
09:39:56.016 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param%5Bname%5D=Bob&param%5Bage%5D=8&param%5Bheight%5D=120
09:39:56.023 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param%5Bname%5D=AAA&param%5Baddress%5D=here
09:39:56.032 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?ssv=a+b+c+d+e%2Cf%2Cg
09:39:56.037 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?ssv=name+Bob+age+8+height+120
09:39:56.041 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?ssv=name+AAA+address+here
09:39:56.055 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=tree%2Cspruce%2Cseed
09:39:56.066 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=name%7CPizza+Garden%7Caddress%7CHome+Street+2
09:39:56.077 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?multi=a&multi=b&multi=c%2Cd
09:39:56.085 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?name=Bob&age=8&height=120
09:39:56.092 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?name=AAA&address=here
09:39:56.103 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?csv=a%2Cb%2Cc
09:39:56.109 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?csv=name%2CBob%2Cage%2C12
09:39:56.115 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?csv=name%2CAAA%2Caddress%2Chere
09:39:56.125 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=a%7Cb%7Cc%7Cd%7Ce%2Cf%2Cg
09:39:56.130 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=name%7CBob%7Cage%7C8%7Cheight%7C120
09:39:56.134 [Test worker] DEBUG i.m.h.client.netty.DefaultHttpClient - Sending HTTP GET to http://localhost:55952/format/queryIdentity?param=name%7CAAA%7Caddress%7Chere

So I guess the problem lies with DefaultHttpClient?