Java 8 Optional<?> validation unwrapper in Spring -

in spring boot project when using following validation rules in dto

@length(max = 70) @unwrapvalidatedvalue private optional<string> vendorname; 

i getting following exception

javax.validation.validationexception: hv000182: no validation value unwrapper registered type java.util.optional<java.lang.string> 

i can't find anywhere how register custom validation value unwrapper in spring

you should register validatedvalueunwrapper validator.

the validator configured via localvalidatorfactorybean:

<?xml version="1.0" encoding="utf-8"?> <beans xmlns="http://www.springframework.org/schema/beans"   xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"   xmlns:util="http://www.springframework.org/schema/util"   xsi:schemalocation="     http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd     http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">    <bean name="validator" class="org.springframework.validation.beanvalidation.localvalidatorfactorybean">     <property name="validationpropertymap">       <util:map>         <entry key="hibernate.validator.validated_value_handlers"                 value="com.mycompany.validator.optionalvalidatedvalueunwrapper"/>       </util:map>     </property>   </bean> </beans> 

or in java:

@bean public localvalidatorfactorybean validator() {     localvalidatorfactorybean validator = new localvalidatorfactorybean();     validator.getvalidationpropertymap().put("hibernate.validator.validated_value_handlers",             "com.mycompany.validator.optionalvalidatedvalueunwrapper");     return validator; } 

---

you find proper validatedvalueunwrapper implementation in dropwizard framework (based on optional guava).

public class optionalvalidatedvalueunwrapper extends validatedvalueunwrapper<optional<?>> {      private final typeresolver resolver = new typeresolver();      @override     public object handlevalidatedvalue(final optional<?> optional) {         return optional.ornull();     }      @override     public type getvalidatedvaluetype(final type type) {         resolvedtype resolvedtype = resolver.resolve(type);         return resolvedtype.typeparametersfor(optional.class).get(0).geterasedtype();     } }