Hello Bernd,
I now understand your problem better.
So the cause lies in the target structure into which you want to fetch your
DB results. You need nested structures to map 1:n relationships...
I also had this problem. I came up with the following solutions:
I also define target DTOs that meet my requirements and can be structured /
nested as required. I don't use a REST API, so I don't have to serialize to
JSON, but I also want to define the DB results very precisely for my Vaadin
UIs.
1) JOOQ multiset
This is of course the most elegant way to map 1:n database relationships
directly into a DTO. Lukas has provided plenty of examples and tips, it's
really great. You can use it to build DTO structures that are nested as
deeply as you like and fill them directly with a single JOOQ query, e.g.
something like this
class MyProjectListDTO {
private Integer projectId;
private List<Order> orders;
class Order {
private Integer id;
private List<OrderPosition> positions;
}
class OrderPosition {
private Integer id;
private String name;
private CustomerAddress address;
}
}
etc.
2) composition of pojos
Here you can build a DTO that contains any number of JOOQ pojos in a flat
structure.
e.g.
class MyProjectListDTO {
private Project project;
private Order order;
private Customer customer;
}
When fetching, you can get help from a 3rd party library (modelmapper.org),
which fills the class attributes of your DTO automatically with the help of
prefixes of the DB result columns.
3) DTO extends POJO
You can of course also derive your DTO from a POJO and extend it
accordingly.
Unfortunately, this does not work for JOOQ Records, as Lukas has already
explained here in the group.
I hope this helps you a bit, because I have the feeling, without knowing
all the details of course, that manual readjustment of the POJOS is not
really necessary.
Kind regards
Dominik
[email protected] schrieb am Donnerstag, 29. August 2024 um 18:26:44
UTC+2:
> Hello Dominik and Lukas,
>
> you are both right about that if i use the generated code as-is
> (either by not checking it into git, or by letting it reside in the
> "generated"-folder)
> i would not run into my described problem
>
> - If checked in, the mergers could just assume that the code in the
> "generated"-folder is ok as auto-generated
> and would not need to be reviewed.
> - If not checked in, there would be no problem as it does not show in the
> merge at all.
>
> ---
> Lukas assumption in his last comment is correct.
>
> - My use-case is, that i need to hand-write my POJOs in a way to match the
> generated code
>
> My use-case is described as follow as example with a new database-table:
> - 1. i create a liquibase-migration that creates the new database-table(s)
> - 2. i run the jooq-codegenerator which creates the Pojos for those new
> database-table(s)
> - 3. i copy the Pojos from the "generated"-folder into the project
> "source"-folder
> - 4. i now change the Pojos in the "source"-folder by adding relationships
> between the Pojos to create a "nested" structure that reflects the
> database-relationships (i rename the Pojos to DTOs also)
> - 5. The so created DTOs need to be Serializable by Jackson to create JSON
> and return this nested-json to the Frontend for consumption.
>
> This would be one of the typical use-cases why i need to hand-write my
> POJOs (DTOs) and not use the generated code for all my use-cases (only for
> some).
>
> - If The database-table(s) are changed now, i need a way to detect that i
> need to change my handwritten Pojos to be noticed of those changes.
> - For this i let my handwritten Pojos implement the jooq generated
> Interfaces, which work great so far!
> - Sadly the Getters / Setters in my handwritten Pojos need to be reviewed
> by the Mergers and i search for a way to make my handwritten pojos more
> simple, while still be noticed of changes.
>
> ----
>
> The best solution would be to use as less handwritten code as possible,
> but for now i see no way to get rid of the hand-written pojos, so i seek
> for a way to get rid of the getters / setters.
> Java14 Records of Frameworks like "Lombok" seem to be able to help here.
>
> But it's not really an important problem to me, - it's only a small
> nuisance, which is also totally fine to work with :)
>
> [email protected] schrieb am Donnerstag, 29. August 2024 um 07:07:32 UTC:
>
>> Thanks for your message, Bernd,
>>
>> Well that "specification" that you're talking about is just the previous
>> version of your schema. You could generate interfaces from your schema with
>> jOOQ (use the <interfaces/> flag) in a code generation run 1, then in code
>> generation run 2, re-generate the records, and try to compile them against
>> the previously generated interfaces. You can add interfaces to any
>> generated class using generator strategies, e.g.:
>>
>> https://www.jooq.org/doc/latest/manual/code-generation/codegen-matcherstrategy/
>>
>> This does what you're asking for.
>>
>> But I'm not really sure I understand the underlying use-case here. Is
>> this because you would like to hand-write your POJOs in a way to match the
>> generated code, but for some reason, *not* use the code generator for this?
>>
>> On Wed, Aug 28, 2024 at 8:47 PM 'Bernd Huber' via jOOQ User Group <
>> [email protected]> wrote:
>>
>>> I want to ask about the ".withRecords(true)" Functionality of the
>>> Jooq-Codegenerator...
>>>
>>> - is it possible to let those Pojos (which are generated as
>>> java14-records) adhere to some specification, that makes sure that whenever
>>> the db-table-schema changes i get a error in my IDE to see that i need to:
>>> - add a field
>>> - remove a field
>>> - rename a field
>>>
>>> With specification a Java-Interface would be optimal.
>>>
>>> I guess the Java-Interface should work if it defines the default-getters
>>> of the java14-records.
>>>
>>> For example:
>>>
>>> public interface PersonSpec { String name(); int age(); }
>>>
>>> public record Person(String name, int age) implements PersonSpec {
>>> // No additional methods needed; the record already provides them.
>>> }
>>>
>>>
>>> ---
>>>
>>> i currently think about using java14-Records instead of normal Pojos
>>> (with getters/setters) because the getters/setters can be harder to review
>>> in merge-requests. The getters/setters are often so much code that the
>>> review-person in the merge-request has much to review, while it would only
>>> be fields.
>>>
>>> But i don't want to loose the advantage of letting the Pojo implement
>>> and interface, which makes sure that if my db-table changes its schema i am
>>> forced to also fix the Pojo for that.
>>>
>>> --
>>>
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>>>
>>
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