JAX-RS - JSON List to Object with JaxB - json

Question

I am using JAX-RS (CXF) with JaxB and Jackson to provide a REST-API.
Unfortunately, none of the found results helps me with following (simple) problem:
I implemented following method:
#POST
#Path(ApiStatics.ARMY_CREATE_ARMY)
public com.empires.web.dto.Army createArmy(#FormParam("locationid") long locationId, #FormParam("name") String name, #FormParam("troops") ArmyTroops troops) {
and here are is my model class:
#XmlRootElement
#XmlSeeAlso(ArmyTroop.class)
public class ArmyTroops {
public ArmyTroops() {
}
public ArmyTroops(List<ArmyTroop> troops) {
this.troops = troops;
}
#XmlElement(name = "troops")
private List<ArmyTroop> troops = new ArrayList<ArmyTroop>();
public List<ArmyTroop> getTroops() {
return troops;
}
public void setTroops(List<ArmyTroop> troops) {
this.troops = troops;
}
}
ArmyTroop
#XmlRootElement(name = "troops")
public class ArmyTroop {
#XmlElement
private long troopId;
#XmlElement
private String amount;
public long getTroopId() {
return troopId;
}
public void setTroopId(long troopId) {
this.troopId = troopId;
}
public String getAmount() {
return amount;
}
public void setAmount(String amount) {
this.amount = amount;
}
}
My json that i send looks like this:
locationid 1
name asdasd
troops {"troops":[{"troopId":4,"amount":"5"},{"troopId":6,"amount":"5"}]}
Unfortunately, the object gets not transformed. Instead I receive this error:
InjectionUtils #reportServerError - Parameter Class com.empires.web.dto.in.ArmyTroops has no constructor with single String parameter, static valueOf(String) or fromString(String) methods
If I provide the constructor with a single string parameter, I get passed the whole json string for "troops" as mentioned above.
Any ideas why JaxB does not work at this point?

Answer 1

You are passing all your parameters with #Form annotation.
But the Form part of the http message must be an xml data structure.
Your 3 parameters don't have a main xml datastructure so it wont work.
In short, form params are send as body.
Cxf use the MultivaluedMap to send params (cxf have an xml model for this structure).
As you can see it is not fit for parameters that can't be trivally serialized.
Here me solution would be to drop the #FormParam to avoid the problem:
1) Use #PathParam #CookieParam to send yours first 2 parameters, and the 'no tag' (body) only for the army compositions.
2) Define an uber object that take all parameters and can be serialized as xml datastructure and use the 'no tag' (body) sending.
3) Use soap, with cxf it is really easy to gets both Rest and Soap.