MapStruct for automatic mapping in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a MapStruct mapper interface.

Spring Boot

import org.mapstruct.Mapper;

@Mapper
public interface [1] {
    // mapping methods
}

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AUserController

BUserService

CUserRepository

DUserMapper

Attempts:

3 left

💡 Hint

Common Mistakes

Using service or controller names instead of mapper interface names.

Forgetting to annotate the interface with @Mapper.

The interface annotated with @Mapper should be named as a Mapper, like UserMapper.

2fill in blank

medium

Complete the code to define a mapping method from UserEntity to UserDTO.

Spring Boot

UserDTO [1](UserEntity userEntity);

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Amap

Bconvert

Csave

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names like 'save' or 'delete' which are unrelated to mapping.

Using generic names that do not indicate mapping.

MapStruct mapping methods are often named 'map' to indicate conversion.

3fill in blank

hard

Fix the error in the mapper implementation retrieval code.

Spring Boot

UserMapper mapper = [1].INSTANCE;

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AUserMapperImpl

BUserMapper

CMapperFactory

DMapperInstance

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to access INSTANCE from the implementation class name.

Using unrelated class names to get the mapper instance.

MapStruct generates an INSTANCE field in the mapper interface for accessing the implementation.

4fill in blank

hard

Fill both blanks to define a mapper with component model 'spring' and specify unmapped target policy to ignore.

Spring Boot

@Mapper(componentModel = "[1]", unmappedTargetPolicy = ReportingPolicy.[2])
public interface UserMapper {
    UserDTO map(UserEntity userEntity);
}

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Aspring

Bdefault

CIGNORE

DWARN

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'default' instead of 'spring' for componentModel when integrating with Spring.

Using WARN instead of IGNORE for unmappedTargetPolicy when you want to suppress warnings.

Setting componentModel to 'spring' allows Spring to manage the mapper bean. Setting unmappedTargetPolicy to IGNORE suppresses warnings for unmapped fields.

5fill in blank

hard

Fill all three blanks to create a mapping method that maps 'name' from source to 'fullName' in target and ignores 'age'.

Spring Boot

@Mapping(source = "[1]", target = "[2]")
@Mapping(target = "[3]", ignore = true)
UserDTO map(UserEntity userEntity);

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Aname

BfullName

Cage

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up source and target field names.

Forgetting to ignore the 'age' field properly.

The 'name' field from source maps to 'fullName' in target. The 'age' field is ignored in mapping.