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https://issues.apache.org/jira/browse/SOLR-6645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14196684#comment-14196684
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Fabio Piro edited comment on SOLR-6645 at 11/4/14 7:56 PM:
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Hi [~bertbrecht42], thanks for the reply.
A *SolrServer#setBinder(BinderInterface binder)* could be an easy and pretty
solution, but it wouldn't solve the need to (copy and paste\rewrite) ALL the
current impl (at the moment coupled as an inner private class). My proposal
tried to solve this exact problem.
was (Author: dewos):
Hi [~bertbrecht42], thanks for the reply.
A *SolrServer#setBinder(DocumentObjectBinderInterface binder)* could be an easy
and pretty solution, but it wouldn't solve the need to (copy and paste\rewrite)
ALL the current impl (at the moment coupled as an inner private class). My
proposal tried to solve this exact problem.
> Refactored DocumentObjectBinder and added AnnotationListeners
> -------------------------------------------------------------
>
> Key: SOLR-6645
> URL: https://issues.apache.org/jira/browse/SOLR-6645
> Project: Solr
> Issue Type: Improvement
> Components: clients - java
> Affects Versions: 4.10.2
> Reporter: Fabio Piro
> Labels: annotations, binder, listener, solrj
> Fix For: 5.0, Trunk
>
> Attachments: SOLR-6645.patch
>
>
> Hello good people.
> It is understandable that the priority of SolrJ is to provide a stable API
> for java and not a rich-feature client, I'm well aware of that. On the other
> hand more features nowadays mean most of the time Spring Solr Data. Although
> I appreciate the enrichment work of that lib, sometimes depending on its
> monolithic dependencies and magic is not a valid option.
> So, I was thinking that the official DocumentObjectBinder could benefit from
> some love, and I had implemented a listener pattern for the annotations.
> *Note: No new logic or new annotations were introduced, the patch is only a
> refactor to make more extendible (for the user) the current
> DocumentObjectBinder and @Field DocField.*
> You can register your annotations and they relate listeners in the binder,
> and it will invoke the corresponding method in the listener on getBean and on
> toSolrInputDocument, therefore granting the chance to do something during the
> ongoing process. Like this:
> {code:java}
> public static void main(String[] args) {
> Map<Class<? extends Annotation>, Class<? extends
> AnnotationListener>> annotations = new HashMap<>();
> annotations.put(FieldObject.class,
> FieldObjectAnnotationListener.class);
> annotations.put(Document.class, DocumentAnnotationListener.class);
> DocumentObjectBinder binder = new DocumentObjectBinder(annotations);
> SolrServer server = new HttpSolrServer("...");
> server.setBinder(binder);// reusable on many servers
> }
> {code}
> Changes are:
> * [MOD] */beans/DocumentObjectBinder*: The new logic and a new constructor
> for registering the annotations
> * [ADD] */impl/AccessorAnnotationListener*: Abstract utility class with the
> former get(), set(), isArray, isList, isContainedInMap etc...
> * [ADD] */impl/FieldAnnotationListener*: all the rest of DocField for dealing
> with @Field
> * [ADD] */AnnotationListener*: the base listener class
> * [MOD] */SolrServer*: added setBinder (this is the only tricky change, I
> hope it's not a problem).
> It's all well documented and the code is very easy to read. Tests are all
> green, it should be 100% backward compatible and the performance impact is
> void (the logic flow is exactly the same as now, and I only changed the bare
> essentials and nothing more, anyway).
> Some Examples (they are not part of the pull-request):
> The long awaited @FieldObject in 4 lines of code:
> https://issues.apache.org/jira/browse/SOLR-1945
> {code:java}
> public class FieldObjectAnnotationListener extends
> AccessorAnnotationListener<FieldObject> {
> public FieldObjectAnnotationListener(AnnotatedElement element,
> FieldObject annotation) {
> super(element, annotation);
> }
> @Override
> public void onGetBean(Object obj, SolrDocument doc, DocumentObjectBinder
> binder) {
> Object nested = binder.getBean(target.clazz, doc);
> setTo(obj, nested);
> }
> @Override
> public void onToSolrInputDocument(Object obj, SolrInputDocument doc,
> DocumentObjectBinder binder) {
> SolrInputDocument nested = binder.toSolrInputDocument(getFrom(obj));
> for (Map.Entry<String, SolrInputField> entry : nested.entrySet()) {
> doc.addField(entry.getKey(), entry.getValue());
> }
> }
> }
> {code}
> Or something entirely new like an annotation for ChildDocuments:
> {code:java}
> public class ChildDocumentsAnnotationListener extends
> AccessorAnnotationListener<ChildDocuments> {
> public ChildDocumentsAnnotationListener(AnnotatedElement element,
> ChildDocuments annotation) {
> super(element, annotation);
> if (!target.isInList || target.clazz.isPrimitive()) {
> throw new BindingException("@NestedDocuments is applicable only
> on List<Object>.");
> }
> }
> @Override
> public void onGetBean(Object obj, SolrDocument doc, DocumentObjectBinder
> binder) {
> List<Object> nested = new ArrayList<>();
> for (SolrDocument child : doc.getChildDocuments()) {
> nested.add(binder.getBean(target.clazz, child));// this should be
> recursive, but it's only an example
> }
> setTo(obj, nested);
> }
> @Override
> public void onToSolrInputDocument(Object obj, SolrInputDocument doc,
> DocumentObjectBinder binder) {
> SolrInputDocument nested = binder.toSolrInputDocument(getFrom(obj));
> doc.addChildDocuments(nested.getChildDocuments());
> }
> }
> {code}
> In addition, all the logic is encapsulated in the listener, so you can make a
> custom FieldAnnotationListener too, and override the default one
> {code:java}
> public class CustomFieldAnnotationListener extends FieldAnnotationListener {
> private boolean isTransientPresent;
> public CustomFieldAnnotationListener(AnnotatedElement element, Field
> annotation) {
> super(element, annotation);
> this.isTransientPresent =
> element.isAnnotationPresent(Transient.class);
> }
> @Override
> public void onGetBean(Object obj, SolrDocument doc, DocumentObjectBinder
> binder) {
> if(!isTransientPresent){
> super.onGetBean(obj, doc, binder);
> }
> }
> @Override
> public void onToSolrInputDocument(Object obj, SolrInputDocument doc,
> DocumentObjectBinder binder) {
> if(!isTransientPresent){
> super.onToSolrInputDocument(obj, doc, binder);
> }
> }
> }
> {code}
> I think this is a good solution for a win-win scenario:
> - The code is almost unchanged (only shifted, wisely changed) so there is no
> new code to test and to support for the devs.
> - People who only need the plain @Field will be untouched and unaware of the
> change.
> - People who need some extra functionalities (like converters) can now easily
> extend the @Field logic, or make new annotations.
> - With some luck, a Community-Driven repository with the most useful features
> can emerge.
> - [Bonus] The binder is now entirely documented and not so scarier like
> before (we are almost at Halloween, but still... :) )
> The code is production-ready, if you are interested in merging it to the
> core, we can discuss the last touch (mainly what to leave protected and what
> to set private).
> ---
> Update1: Added PATCH
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