/*
* Copyright 2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.mapping;
import java.util.Optional;
/**
* Interface for a component allowing the access of identifier values.
*
* @author Oliver Gierke
* @see TargetAwareIdentifierAccessor
*/
public interface IdentifierAccessor {
/**
* Returns the value of the identifier.
*
* @return the identifier of the underlying instance.
*/
Optional<Object> getIdentifier();
/**
* Returns the identifier of the underlying instance. Implementations are strongly recommended to extends either
* {@link TargetAwareIdentifierAccessor} or override this method to add more context to the exception being thrown in
* case of the absence of an identifier.
*
* @return the identifier of the underlying instance
* @throws IllegalStateException in case no identifier could be retrieved.
* @since 2.0
*/
default Object getRequiredIdentifier() {
return getIdentifier().orElseThrow(() -> new IllegalStateException(String.format("Could not obtain identifier!")));
}
}