I have the same feeling and arguments.

On 21 Nov 2016, at 17:25, Christian Kaltepoth <christian@kaltepoth.de> wrote:

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@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@hibernate.org>:

On 7 Nov 2016, at 23:42, Hendrik Ebbers <hendrik.ebbers@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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Christian Kaltepoth

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