how to pass parameter #Payload - spring-integration

Question

i have code
<int:channel id="partnerConfigChannel" />
<int:gateway id="partnerService" service-interface="org.service.PartnerService"
default-request-timeout="5000" default-reply-timeout="5000">
<int:method name="findConfig" request-channel="partnerConfigChannel" />
</int:gateway>
<int-jpa:retrieving-outbound-gateway entity-manager="entityManager"
request-channel="partnerConfigChannel"
jpa-query="select q from QueueConfiguration q where q.partnerId = :partnerId">
<int-jpa:parameter name="partnerId" expression="payload['partnerId']" />
</int-jpa:retrieving-outbound-gateway>
and java interface
public interface PartnerService {
#Payload("partnerId")
List<QueueConfiguration> findConfig();
}
i am calling it
List<QueueConfiguration> qc= partnerService.findConfig();
but i am getting exception
EL1007E:(pos 0): Property or field 'partnerId' cannot be found on null
please tell me how can i pass payload . i tried by passing Message object with a map , string but same error .
please tell me how can i pass payload in such case.

Answer 1

#Payload("partnerId")
At this point, there is no object for the SpEL expression to be evaluated against.
It either needs to be a literal
#Payload("'partnerId'")
Or refer to some other bean.
Further, on your adapter, you are expecting the payload to be a map with key partnerId.
expression="payload['partnerId']"
So this won't work.
If you want to pass a variable, you should do something like this...
public interface PartnerService {
List<QueueConfiguration> findConfig(MyClass param);
Where MyClass has some property 'partnerId'.
or
List<QueueConfiguration> findConfig(String partnerId);
and
expression="payload"
I suggest you do some more reading.

Answer 2

i modified my code
public interface PartnerService {
List<QueueConfiguration> findConfig(#Payload Message msg);
}
and the call it like
Map msgMap=new HashMap();
msgMap.put("partnerId", partnerId);
Message msg=MessageBuilder.withPayload(msgMap).build();
List<QueueConfiguration> qc= partnerService.findConfig(msg);
and it is working fine.