Apache Camel - call simple language without side effect - apache-camel

Question

Is it possible to call an object with the Simple language directly within the route and without side effects? The 2 approaches i've tried are;
.toD("${header.exchangeHelper.inc1()}") //works but fails if there is a return type from the called method
.bean(new Simple("${header.exchangeHelper.inc1()}")) //works but sets the body to false
Neither of which give the ideal solution.

Answer 1

You can store the result to exchange property or header instead. This way you'll keep the original body and get the result from your method in case you need it later. Alternatively you can just call the method using a processor.
These are generally better approaches with Java-DSL for something like this than using simple-language since they benefit from IDE's refactoring tools, error highlighting and many forms of linting.
package com.example;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
import org.apache.camel.Exchange;
import org.apache.camel.RoutesBuilder;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.mock.MockEndpoint;
import org.apache.camel.test.junit4.CamelTestSupport;
import org.junit.Test;
public class ExampleTest extends CamelTestSupport {
ExchangeHelper exchangeHelper = mock(ExchangeHelper.class);
#Test
public void useSetPropertyTest() throws Exception {
MockEndpoint resultMockEndpoint = getMockEndpoint("mock:result");
resultMockEndpoint.expectedMessageCount(1);
resultMockEndpoint.message(0).body().isEqualTo("Hello");
when(exchangeHelper.inc1()).thenReturn(true);
template.sendBodyAndHeader("direct:useSetProperty", "Hello",
"exchangeHelper", exchangeHelper);
verify(exchangeHelper, times(1)).inc1();
resultMockEndpoint.assertIsSatisfied();
}
#Test
public void justUseProcessorTest() throws Exception {
MockEndpoint resultMockEndpoint = getMockEndpoint("mock:result");
resultMockEndpoint.expectedMessageCount(1);
resultMockEndpoint.message(0).body().isEqualTo("Hello");
when(exchangeHelper.inc1()).thenReturn(true);
template.sendBody("direct:justUseProcessor", "Hello");
verify(exchangeHelper, times(1)).inc1();
resultMockEndpoint.assertIsSatisfied();
}
#Test
public void useHeaderFromProcessorTest() throws Exception {
MockEndpoint resultMockEndpoint = getMockEndpoint("mock:result");
resultMockEndpoint.expectedMessageCount(1);
resultMockEndpoint.message(0).body().isEqualTo("Hello");
when(exchangeHelper.inc1()).thenReturn(true);
template.sendBodyAndHeader("direct:useHeaderFromProcessor", "Hello",
"exchangeHelper", exchangeHelper);
verify(exchangeHelper, times(1)).inc1();
resultMockEndpoint.assertIsSatisfied();
}
#Override
protected RoutesBuilder createRouteBuilder() throws Exception {
return new RouteBuilder(){
#Override
public void configure() throws Exception {
from("direct:useSetProperty")
.setProperty("result")
.simple("${header.exchangeHelper.inc1()}")
.log("Body: ${body} Result header: ${exchangeProperty.result}")
.to("mock:result")
.removeProperty("result");
from("direct:justUseProcessor")
.process( ex -> { exchangeHelper.inc1(); })
.log("Body: ${body}")
.to("mock:result");
from("direct:useHeaderFromProcessor")
.process( ex -> {
ex.getMessage()
.getHeader("exchangeHelper", ExchangeHelper.class)
.inc1();
})
.log("Body: ${body}")
.to("mock:result");
}
};
}
interface ExchangeHelper {
public boolean inc1();
}
}

Answer 2

Not tried, but why not using the wiretap EIP to issue an extra (and separated!) request to your requestHelper method ?
Something like:
from("direct:demo")
.wireTap("bean:${header.exchangeHelper.inc1()}")
.to("direct:doSomething");

Answer 3

You can simply use Camel Script, something like that:
from("direct:exampleScript")
.script().simple("${header.exchangeHelper.inc1()}")
.log("End")
;