Hazelcast query in custom objects

Question

I'm using Hazelcast as a shared map in my application. My map is like that:

Map<String, MyObject>

and MyObject:

class MyObject implements Serializeble {
    // Map FieldName -> FieldValue
    Map<String, Object> myMap;
}

So I'd like to use Hazelcast distributed query support to query in my object. I've checked that Hazelcast uses get's method to retrieve the object value, but in my case I don't have a get, instead of I'd like to implement my own getField like:

Object getField(String fieldName) {
    return myMap[fieldName];
}

And force Hazelcast to call this method. As a workaround, I've hacked Hazelcast code to use a CustomGetter in the class

/hazelcast/src/main/java/com/hazelcast/query/impl/ReflectionHelper.java

line 144:

if (localGetter == null) {
    localGetter = new CustomFieldGetter(name, obj);
}

and here My CustomFieldGetter class:

static class CustomFieldGetter extends Getter {
    final Object value;
    final Class type;
    final String fieldName;

    CustomFieldGetter(String fieldName, Object obj) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        super(null);
        this.fieldName = fieldName;
        this.value = obj.getClass().getMethod("getField", String.class).invoke(obj, fieldName);
        this.type = value.getClass();
    }

    @Override
    Object getValue(Object obj) throws Exception {
        return value;
    }

    @Override
    Class getReturnType() {
        return type;
    }

    @Override
    boolean isCacheable() {
        return false;
    }

    @Override
    public String toString() {
        return "FieldGetter [parent=" + parent + ", field=" + fieldName + "]";
    }
}

Ok cool, after recompilation of Hazelcast, and using this new jar, I could reach queries using plain sql. But for pagingQueries I got some errors.

So my finally question is: I'd like to avoid hack Hazelcast code (for further updates). Does Hazelcast has some supports on this issue? Is there any other solution for this problem?

PS: I'm using Hazelcast version -> hazelcast-3.3-RC3

Thanks in advance.

Answer 1

one option is to implement Portable interface. Then you could write each entry as a separate field. This assumes the entry value implements the Portable interface as well.

Look at the sample code how to use Portable.