Jooq: Add <enumConverter/> flag in <forcedType/> to auto-generate EnumConverter

[axelfontaine]

Enum converters follow a pretty dumb pattern. For example:

public class AppTypeConverter extends EnumConverter<String, AppType> {
    public AppTypeConverter() {
        super(String.class, AppType.class);
    }
}

Couldn't this work somehow be picked up by the jOOQ generator instead of having to do it manually?

Suggestion:

<forcedType>
    <userType>com.abc.AppType</userType>
    <enumConverter/>
    <expression>.*app_type</expression>
    <types>text</types>
</forcedType>

And the generator would then detect the <enumConverter/> tag and generate the specific converter.

[lukaseder]

Thanks a lot for your suggestion. You're right and I've thought about this myself, before - I don't know why I didn't follow up with this thought.

Will definitely implement this for 3.10

[lukaseder]

I have thought about this again. I think we can go ahead exactly as suggested, including the XML element name. The XSD specification will be amended from:

      <element name="converter" type="string" minOccurs="0" maxOccurs="1" />

to

      <choice>
        <element name="converter" type="string" minOccurs="0" maxOccurs="1" />
        <element name="enumConverter" type="boolean" minOccurs="0" maxOccurs="1" fixed="true" />
      </choice>

XJC doesn't reflect this choice element, nor the fixed attribute, but I think it will be clear from the API what is meant, if users use this feature programmatically.

[lukaseder]

Hmm, it looks as though the fixed semantics is not supported in this way when going through the Maven plugin. I guess we'll have to require users to explicitly pass the flag:

    <enumConverter>true</enumConverter>

[axelfontaine]

Have you considered the alternative: keeping the same tag but using a special value that can't possibly conflict with a valid class name. For example:

<converter>[ENUM]</converter>

This would have the advantage of making it easy to add other special generated converters over time without changing the XML schema.

[lukaseder]

I'd rather not cleverly recycle XML elements. That will make things rather confusing, e.g.:

• Documentation
• Implementation
• Future features that are not possible to model with a simple "tag"

[axelfontaine]

How about a mixture of both approaches:

<autoConverter>enum</autoConverter>

(This adds extensibility, but then again it most likely doesn't cover cases like #5876 )

[lukaseder]

Same problem:

• Future features that are not possible to model with a simple "tag"

What if an <autoConverter> needs additional parameters?

[axelfontaine]

Point taken. I agree with you.

[lukaseder]

OK, implementing <enumConverter>true</enumConverter> right now.

[lukaseder]

Finally documented this in the manual for versions 3.10+: https://github.com/jOOQ/jOOQ/issues/6932