Set a spring integration router attribute programmatically

Question

We have a Spring Integration route using a Router with an expression. This expression is set in the yml file. I would like to create unit tests setting manually the value for this router attribute, but it doesn't seem to work.

Test

@Autowired
EventDrivenConsumer myrouter;
.....
((ExpressionEvaluatingRouter) myrouter.getHandler()).setPrimaryExpression(new SpelExpressionParser().doParseExpression("true"));

Part of the XML context

<int:router input-channel="catchweightExcluderChannel" expression="${rip.config.exclude_catchweight}" default-output-channel="productTransformerChannel">
    <int:mapping value="true" channel="catchWeightFilteringChannel" />
    <int:mapping value="false" channel="productTransformerChannel" />
</int:router>

But it seems my value overrided is not affecting the behaviour...it seems as once Spring reads the context, changing attributes of components does not affect their behaviour.

Artem Bilan · Accepted Answer · 2017-03-02 15:29:13Z

1

You can't change the property that way because expression is a ctor arg for the ExpressionEvaluatingRouter:

public class ExpressionEvaluatingRouter extends AbstractMessageProcessingRouter {

    public ExpressionEvaluatingRouter(Expression expression) {
        super(new ExpressionEvaluatingMessageProcessor<Object>(expression));
        setPrimaryExpression(expression);
    }

}

I think for your test use-case the @TestPropertySource would be the best solution:

@RunWith(SpringRunner.class)
@TestPropertySource(properties = "rip.config.exclude_catchweight:true")

UPDATE

but then why is there a mutator called setPrimaryExpression

The setPrimaryExpression() and its sibling getExpression() for visualization tools and logs to make expression-based components much cleaner for analysis. Since one components may have several expressions, we decided to distinguish a prime one and therefore that name for a setter.

The real hard work for expression evaluation is done there in the ExpressionEvaluatingMessageProcessor, which is ctor-based as well, as we see.

For your per method requirements I only can suggests to create ApplicationContext manually and call its setEnvironment(new MockEnvironment(). And already there you can populate a desired value for that expression in particular case.

You can't override that ctor-based initialization when your application context is already started.

edited Mar 2, 2017 at 15:29

answered Feb 28, 2017 at 16:59

Artem Bilan

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3 Comments

JonathanVila Over a year ago

Oki, it's a constructor arg, but then why is there a mutator called setPrimaryExpression ?

JonathanVila Over a year ago

About the TestPropertySource is a class level annotation, so to test both true and false values I need to create 2 test classes instead of 2 methods . So, although I can put DirtiesContext at method level, I can not set anything overriding the properties at method level ?

Artem Bilan Over a year ago

See an UPDATE in my answer.

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