how to pass namedQuery parameters in Apache Camel JPA by header? - jpa

Question

I have this camel route:
from("direct:getUser")
.pollEnrich("jpa://User?namedQuery=User.findById&consumeDelete=false");
This is my user Entity:
#Entity
#NamedQueries({
#NamedQuery(name="User.findAll", query="SELECT u FROM User u"),
#NamedQuery(name="User.findById", query="SELECT u FROM User u WHERE u.id = :id")
})
public class User{
#Id
private String id;
}
I have tried this route by setting the header:
from("direct:getUser")
.setHeader("id", simple("myid"))
.pollEnrich("jpa://User?namedQuery=User.findById&consumeDelete=false");
But it is not working
Is there any method to set jpa properties by the headers? The camel documentation quote this in parameters option but i don't found the examples
Options: parameters
This option is Registry based which requires the # notation. This
key/value mapping is used for building the query parameters. It is
expected to be of the generic type java.util.Map where
the keys are the named parameters of a given JPA query and the values
are their corresponding effective values you want to select for. Camel
2.19: it can be used for producer as well. When it's used for producer, Simple expression can be used as a parameter value. It
allows you to retrieve parameter values from the message body header
and etc.

Answer 1

I hope it's not too late to answer. In any case I had a similar issue in my project, the client does a HTTP GET with a parameter id, which is used by the JPA query and the result is finally marshalled back to the HTTP client. I'm running camel in a Spring application.
I finally figured out how to achieve it in a reasonably clean way.
This is the RouteBuilder where the route is defined:
#Override
public void configure() throws Exception {
Class dataClass = SomeClass.class;
JacksonDataFormat format = new JacksonDataFormat();
format.setUnmarshalType(dataClass);
String jpaString = String
.format("jpa://%1$s?resultClass=%1$s&namedQuery=q1" +
"&parameters={\"id\":${headers.id}}", dataClass.getName());
from("jetty://http://localhost:8080/test").toD(jpaString) // note the .toD
.marshal(format)
}
And this is the StringToMapTypeConverter class, otherwise camel cannot convert {"id": X} to a map
public class StringToMapTypeConverter implements TypeConverters {
private static final ObjectMapper mapper = new ObjectMapper();
private static JavaType mapType;
static {
mapType = mapper.getTypeFactory().constructMapType(Map.class,
String.class, Object.class);
}
#Converter
public Map<String, Object> toMap(String map) throws IOException {
return mapper.readValue(map, mapType);
}
}
Remember to add it to the context. In Spring is something like:
<bean id="myStringToMapTypeConverter" class="....StringToMapTypeConverter" />
Refs:
http://camel.apache.org/jpa.html
http://camel.apache.org/message-endpoint.html#MessageEndpoint-DynamicTo
http://camel.apache.org/type-converter.html#TypeConverter-Addtypeconverterclassesatruntime