Re: [aspectj-users] How to access advice aspect's fields without reflect

[Eric B <ebenzacar@xxxxxxxxx>]

Thanks Andy,

That's what I was thinking as well.  However, one thing that I haven't been able to find is how to get the type of obj that needs to be instantiated.

Currently, it is a Validity object.  However, if I wanted to do this more generically, I would want to do something like:

value = thisJoinPoint.getSignature().fieldType.newInstance()

However, I can't seem to find any way to get "fieldType".

Is that information not accessible anywhere?  If not, is there a way to get the expected return type of the get() pointcut?

Tx,

Eric

On Tue, Jul 8, 2014 at 5:26 AM, Andy Clement <andrew.clement@xxxxxxxxx> wrote:

I only had a couple of mins to play but if you went with around advice you could make the reflection only run if initialization is required:

Object around(): embeddedGetter() {

Object value = proceed();

if (value == null) {

String fieldName = thisJoinPoint.getSignature().getName();

Object obj = thisJoinPoint.getThis();

try{

Field field = obj.getClass().getDeclaredField(fieldName);

field.setAccessible(true);

field.set(obj, value = new Validity() );

}

catch( IllegalAccessException | NoSuchFieldException e){e.printStackTrace();}

}

return value;

}

Andy

On 8 July 2014 04:34, Eric B <ebenzacar@xxxxxxxxx> wrote:

I've got the following issue that I am trying to solve with AspectJ.

Given an entity class with a null @Embedded field, when trying to access it with a getter, instantiate it first if it is null.

For example:

@Entity

public class MyClass {

        @Id

private long id;

@Embedded

private Validity validity;

}

And Validity:

@Embeddable

public class Validity{

    private long from;

    private long to;

}

I'm having trouble figuring out how to best write the before() advice however.  Ideally, I'm trying to avoid using reflection for fear of slowing things down, but so far, the best I have been able to come up with is the following:

// define a pointcut for any getter method of a field with @Embedded of type Validity with any name in com.ia.domain package

pointcut embeddedGetter() : get( @javax.persistence.Embedded com.ia.domain.Validity com.ia.domain..* );

before() : embeddedGetter(){

String fieldName = thisJoinPoint.getSignature().getName();

Object obj = thisJoinPoint.getThis();

// check to see if the obj has the field already defined or is null

try{

Field field = obj.getClass().getDeclaredField(fieldName);

field.setAccessible(true);

if( field.get(obj) == null )

field.set(obj, new com.ia.domain.Validity() );

}

catch( IllegalAccessException | NoSuchFieldException e){}

}

Is there a better way?

Thanks,

Eric

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