How to pass a camel exchange property into CacheBasedMessageBodyReplacer processor

[stuelpm]

Hi,

I try to do some tests with the cache component in Camel and would like to pass a Camel exchange property into the CacheBasedMessageBodyReplacer processor.

I tried the following:

     .process(new CacheBasedMessageBodyReplacer("cache://MyApplicationCache", exchangeProperty("CamelTimerCounter").convertToString()))

However the result of exchangeProperty("CamelTimerCounter").convertToString() is of type ValueBuilder while the constructor expects a String.

How can I pass the exchange property as String into the constructor?

Thanks,

Markus

[davsclaus]

The processor is created only once when Camel is starting up and creating the route model.

Therefore you cannot / should not do this. Instead you can get information from the exchange at runtime from the process(Exchange exhange) method, so just do

.process(new CacheBasedMessageBodyReplacer("cache://MyApplicationCache"))

And then in the process method you can get that information

    public void process(Exchange exchange) {

     Object counter = exchange.getProperty("xxx")

     ...

    }

[stuelpm]

Thanks Claus for your reply!

I understood that the processor is created only at once at startup.

The constructor of the CacheBasedMessageBodyReplacer processor, which is provided as part of camel-cache component, expects the cache name and the key as parameter.

So how can I use the approach that you are suggesting? Is there a way to wrap the provided processor into my own processor or something similar?

Thanks,

Markus

[davsclaus]

You can create that processor from inside another processor.

But the processor code is not so good/dynamic as it creates the cache manager instance on each request and the key is not dynamic. So you can actually write a better processor yourself.

[davsclaus]

So this commit made the processor better in the future. You could do something similar yourself

CAMEL-10838: camel-cache - Create a better body replacer processor · apache/camel@bdf4aaa · GitHub

You can then pass in the expression using ExpressionBuilder.exchangePropertyExpression("xxx")