senderic
commented
3 years ago Okay I realized I needed to implement my own MergeStrategy. By doing this, I got the merge to work the way I needed to. I'm not done yet, but I haven enough to show a bit:
package com.yyy.xxxx.data.model.strategies;
import com.yyy.xxxx.common.XxxxRuntimeException;
import com.yyy.xxxx.data.model.gen.Action;
import lombok.extern.log4j.Log4j2;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.lang3.ClassUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.reflect.MethodUtils;
import org.jvnet.jaxb2_commons.lang.JAXBMergeStrategy;
import org.jvnet.jaxb2_commons.locator.ObjectLocator;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Locale;
import java.util.function.Predicate;
import java.util.stream.Collectors;
@Log4j2
public class MergeFlowStrategy extends JAXBMergeStrategy {
@Override
protected Object mergeInternal(ObjectLocator leftLocator, ObjectLocator rightLocator, Collection leftCollection, Collection rightCollection) {
log.debug("\n-leftCollection:\n{}\n-rightCollection:\n{}\n-leftLocator: {}\n-rightLocator: {}\n-left: {}\n-right: {}",
() -> leftCollection.stream().map(Object::toString).collect(Collectors.joining("\n---\n")),
() -> rightCollection.stream().map(Object::toString).collect(Collectors.joining("\n---\n")),
() -> leftLocator, () -> rightLocator, () -> leftCollection, () -> rightCollection);
// This is where the improper merge is taking place. Internally, all that is happening is a swap!
// return super.mergeInternal(leftLocator, rightLocator, leftCollection, rightCollection);
if (CollectionUtils.isEmpty(leftCollection) || CollectionUtils.isEmpty(rightCollection))
return super.mergeInternal(leftLocator, rightLocator, leftCollection, rightCollection);
else {
Collection merge = new ArrayList<>();
leftCollection.forEach(lEl -> mergeBasedOnOperation(leftLocator, rightLocator, rightCollection, merge, lEl));
// Some elements may be in rightCollection and not in leftCollection. Make sure those elements survive.
rightCollection.forEach(rEl -> {
// no operation data will be found here.
Predicate p = elem -> true;
if (StringUtils.equals(ClassUtils.getSimpleName(Action.class), (ClassUtils.getSimpleName(rEl.getClass()))))
p = elem -> ((Action) elem).getOrder() == ((Action) rEl).getOrder();
// TODO will need this for any array element that has a key (Action uses order as a key)
Object lElL = leftCollection.stream().filter(rEl.getClass()::isInstance).map(rEl.getClass()::cast).filter(p).findFirst().orElse(null);
if (lElL == null) merge.add(rEl);
});
return merge;
}
}
private void mergeBasedOnOperation(ObjectLocator leftLocator, ObjectLocator rightLocator, Collection rightCollection, Collection merge, Object elem) {
String operation = getOperation(elem);
switch (operation.toLowerCase(Locale.US)) {
case "none":
Object rightElem = rightCollection.stream().filter(elem.getClass()::isInstance).map(elem.getClass()::cast).findFirst().orElse(null);
Object m = super.merge(leftLocator, rightLocator, elem, rightElem);
merge.add(m);
break;
case "replace":
case "create": // if create, expect rightElem to be null.
merge.add(elem);
break;
case "delete":
break;
}
}
private String getOperation(Object elem) {
String operation;
try {
operation = String.valueOf(MethodUtils.getAccessibleMethod(elem.getClass(), "getOperation").invoke(elem));
} catch (IllegalAccessException | InvocationTargetException e) {
throw new XxxxRuntimeException("Could not get operation info out of element!", e);
}
return operation;
}
Issue
.mergeFrom seems to just do the same thing as .copyTo
Description
I have a need to merge two XML (jaxb based) objects and it seems like the
.mergeFrommethod derived from the JAXBMergeStrategy plugin. I successfully implemented the plugin via maven, however am I finding the usage of.mergeFromto be odd.The name of the object is
Matchso I will refer to the objects as MatchA, MatchB, and MatchBA. My goal is to merge MatchBA with MatchA to attain MatchB.MatchA:
MatchBA:
Expected MatchB:
Or this could come out too:
In the second example, there are two
<ethernet-type>elements since maybe JaxB can't merge that element understandably (I would need to manually prune though and detect an element like that since it won't have anoperationororig-valueattribute).What I actually get:
That's not the expected merge. In fact, it looks just like
BA. I also tried:Besides the top element having
operationandorig-valueattributes, the content ofMatchis the same as A. So, it seems like (not exactly but effectively)B.mergeFrom(BA,A) == A.copyTo(B)andB.mergeFrom(A,BA) == BA.copyTo(B).Questions
.mergeFrom()incorrectly and I am expecting the wrong actions from it, or there is a bug in mergeEnvironment
<glassfish.jaxb-runtime.version>2.3.0-b170127.1453</glassfish.jaxb-runtime.version><javax.jaxb-api.version>2.3.1</javax.jaxb-api.version><jaxb2-basics.version>0.12.0</jaxb2-basics.version><jaxb2-commons-lang.version>2.4</jaxb2-commons-lang.version><jaxb-core.version>2.3.0.1</jaxb-core.version><jaxb-impl.version>2.3.1</jaxb-impl.version>Update
I think I found out why it appears to be more like a copy... https://github.com/highsource/jaxb2-basics/blob/a009a78971d8260daac09e1d5a2024bbd2e19128/runtime/src/main/java/org/jvnet/jaxb2_commons/lang/JAXBMergeStrategy.java#L25