[bv-dev] On the support for Optional (was Re: Support for constraints on container values (e.g. Collection<@Email String>))

[Christian Kaltepoth]

Not sure I like the idea of supporting Optional<T> for return types but not
for fields and method parameters. Is there any technical reason for this
restriction? I agree that using Optional<T> for fields is an anti-pattern,
but I don't see any reason for not supporting it nevertheless.

Am I missing something here?

2016-11-21 15:18 GMT+01:00 Gunnar Morling <gunnar at hibernate.org>:

> Yes, probably we should not support Optional for fields. Also parameters
> are dubious (the JDK team discourages that afaik). But supporting it for
> return values (and getter-based properties) seems reasonable.
>
> 2016-11-21 14:32 GMT+01:00 Emmanuel Bernard <emmanuel at hibernate.org>:
>
>>
>> On 7 Nov 2016, at 23:42, Hendrik Ebbers <hendrik.ebbers at me.com> wrote:
>>
>> I don’t think that support for Optional is that important since having a
>> field of type Optional looks like an anti-pattern to me. Normally Optional
>> should be used as a method return type and not as a type for a field.
>> Supporting it in the bean validation might end in strange model classes.
>>
>> Example:
>>
>> The following model looks good to me:
>>
>> public class Model {
>>
>> @NotNull
>> private String name;
>>
>> public String getName() { return name; }
>>
>> public void setName(String name) { this.name = name; }
>>
>> public Optional<String> name() { return Optional.ofNullable(name);}
>>
>> }
>>
>> On the other hand this looks like an anti-pattern to me:
>>
>> public class Model {
>>
>> @NotNull
>> private Optional<String> name;
>>
>> public Optional<String> getName() { return name; }
>>
>> public void setName(String name) { this.name =
>> Optional.ofNullable(name); }
>>
>> }
>>
>>
>> Yes Optional on a property is deemed an anti pattern by the JDK team but
>> since Bean Validation supports contraints on method parameters and return
>> values, this is still a valid use case
>>
>> Optional<@Email String> getUserEmail(@NotNull UUID userId);
>>
>> Emmanuel
>>
>>
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>
>
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-- 
Christian Kaltepoth
Blog: http://blog.kaltepoth.de/
Twitter: http://twitter.com/chkal
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