Java Community | Help. Code. Learn.•2w ago

How to improve the intuitivity

I am using a LINQ style way to write HQL-Queries. There are other solutions but they bring frameworks I do not like to use. Today I have a good working solution that abuse the unicode charset so the sourcecode must be at least UTF8. My solution is working but I am not sure if this is a good solution for the general public. What to change to the syntax in order to publish it to the public accordingly? Example: We have two Entities: eMail and eMailSubject. A eMail already exists as an hibernate-entity. The function I present is to programaticaly response to that eMail. The task is to add the "Re: "-prefix to the subject. Code:

EMail answer = new EMail();
String targetSubject = "Re: " + original.getSubject().getSubject();
answer.setSubject(SELECT.FROM(囗EMailSubject.class).AS(ES -> WHERE(ES.subject).ㅤᆖㅤ(targetSubject).SELECT().ꁘ(ES))
        .first(entityManager, () -> new EMailSubject(targetSubject)));
entityManager.persist(answer);
return ResponseEntity.ok(answer.getId());

EMail answer = new EMail();
String targetSubject = "Re: " + original.getSubject().getSubject();
answer.setSubject(SELECT.FROM(囗EMailSubject.class).AS(ES -> WHERE(ES.subject).ㅤᆖㅤ(targetSubject).SELECT().ꁘ(ES))
        .first(entityManager, () -> new EMailSubject(targetSubject)));
entityManager.persist(answer);
return ResponseEntity.ok(answer.getId());

21 Replies

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Peter RaderOP•2w ago

Lets break it down to the components:

EMail answer = new EMail();
String targetSubject = "Re: " + original.getSubject().getSubject();
Aliasing<EMailSubject, 囗EMailSubject> aliasScope = SELECT.FROM(囗EMailSubject.class);
Function<囗EMailSubject, HQLQueryContributor> whereFunction = ES -> WHERE(ES.subject).ㅤᆖㅤ(targetSubject).SELECT()
        .ꁘ(ES);
HQLQueryContributor queryBuilder = aliasScope.AS(whereFunction);
Supplier<EMailSubject> noResultPersistFallback = () -> new EMailSubject(targetSubject);
answer.setSubject(queryBuilder.first(entityManager, noResultPersistFallback));
entityManager.persist(answer);
return ResponseEntity.ok(answer.getId());

EMail answer = new EMail();
String targetSubject = "Re: " + original.getSubject().getSubject();
Aliasing<EMailSubject, 囗EMailSubject> aliasScope = SELECT.FROM(囗EMailSubject.class);
Function<囗EMailSubject, HQLQueryContributor> whereFunction = ES -> WHERE(ES.subject).ㅤᆖㅤ(targetSubject).SELECT()
        .ꁘ(ES);
HQLQueryContributor queryBuilder = aliasScope.AS(whereFunction);
Supplier<EMailSubject> noResultPersistFallback = () -> new EMailSubject(targetSubject);
answer.setSubject(queryBuilder.first(entityManager, noResultPersistFallback));
entityManager.persist(answer);
return ResponseEntity.ok(answer.getId());

The benefit is that you have full content-assist in IDEs and you need no additional dependency. The downside is that the sourcecode must be unicode in order to be used correctly. What must be changed in order to present the solution to the public?

dan1st•2w ago

Why do you use special unicode characters there? Can't you just use underscores or similar? There is already the approach of type-safe queries with the Jakarta Criteria API metamodel classes (classes that end with an _ and are generated at compile-time) see https://jakarta.ee/learn/docs/jakartaee-tutorial/current/persist/persistence-criteria/persistence-criteria.html#_using_the_metamodel_api_to_model_entity_classes - you might want to take inspiration from that ;) Also how do you get from the data/entity classes to the generated classes? Are you using annotations on the entities (or however you want to call them)? Are you using an annotation processor to generate these classes?

Peter RaderOP•2w ago

I like to use a unicode-pendant for the equals-sign (=), it is a control-character and not allowed as a method-name. Yes at the moment. I will get rid of generating the intermediate-code due to new language improvements that did not exists before. Example: BiFunction<EMail, EMailSubject, EMail> subjectSetter = EMail::setSubject;

dan1st•2w ago

and this is what it looks like in Discord

dan1st•2w ago

What do you mean with didn't exist before? Method references were available in JDK 8 already... Are you talking about code reflection? Because that would allow you to do it in a type-safe way without generating that code at compile-time

Peter RaderOP•2w ago

I admit that it is an old solution.

dan1st•2w ago

Is there an issue with it being legal method declarations that nobody will use?

Peter RaderOP•2w ago

You mean code-reflection like JpaRepositories? I think I did not made this point clear. If you have a java-method like this: public static void =(String param) {} the compiler will mention that = is not a valid method name.

dan1st•2w ago

Code reflection is a planned Java/JVM feature that should allow Java code to look into a method. So you could do

Query<EMailSubject> query = Query.create(EMailSubject.class);
query.where(subject -> subject.getAddress().equals("[email protected]"));

Query<EMailSubject> query = Query.create(EMailSubject.class);
query.where(subject -> subject.getAddress().equals("[email protected]"));

and then it could actually analyze that and convert it to SQL (without having to look at the bytecode) and it would also be useful for autodifferentiation and GPU stuff but it isn't there yet

Peter RaderOP•2w ago

Nice feature but its a runtime feature, right? Id like to focus on the IDE's content-assist.

Madjosz•2w ago

Do you have a JEP at hand for that?

dan1st•2w ago

There's no JEP yet just talks and I think design documents it's far from being done

Madjosz•2w ago

Ok, so JDK 40+ feature then. Like Valhalla.

dan1st•2w ago

https://www.youtube.com/watch?v=6c0DB2kwF_Q

Java

YouTube

Project Babylon - Code Reflection #JVMLS

Presented by Paul Sandoz - Software Architect (Java Platform Group - Oracle) during the JVM Language Summit (August 2024 - Santa Clara, CA). _Project Babylon aims to extend the reach of Java to foreign programming models with an enhancement to Java reflection called code reflection . Code reflection expands reflective access to ...

dan1st•2w ago

There are relevant JEPs for that

Madjosz•2w ago

Yeah, they are slowly adding features for that

dan1st•2w ago

babylon is fairly new as an OpenJDK project but it won't be as big in scope as Valhalla https://openjdk.org/projects/babylon/ That one would be relevant to this question: https://openjdk.org/projects/babylon/articles/linq

Peter RaderOP•2w ago

About the code-reflection... I remember a discussion with a collegue who like to write a unit-test to make sure a constructor is a pojo-constructor and no other magic happens there, I suggested to ASM-disassemble and check the bytecode-instructions.... The discussion ended with the decision to not unit-test bytecode.

dan1st•2w ago

good idea the better way to do that would probably be the AST API (since you have the source code) and probably do it at compile-time with an annotation processor or similar

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