Entity to DTO mapping in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a DTO class with private fields and public getters.

Spring Boot

public class UserDTO {
    private String [1];

    public String getUsername() {
        return username;
    }
}

Drag options to blanks, or click blank then click option'

Ausername

Buser_id

Cname

DuserName

Attempts:

3 left

💡 Hint

Common Mistakes

Using a field name that does not match the getter method.

Using underscores in variable names in Java.

The field name must match the getter method name. Here, the getter is getUsername(), so the field should be username.

2fill in blank

medium

Complete the code to map an entity's field to a DTO field in the constructor.

Spring Boot

public UserDTO(UserEntity entity) {
    this.username = entity.[1]();
}

Drag options to blanks, or click blank then click option'

AgetUsername

Bget_name

CgetuserName

DgetUserName

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect casing in method names.

Using underscores in method names.

The entity's getter method should follow Java naming conventions. Usually, it is getUsername() for a field named username.

3fill in blank

hard

Fix the error in the mapping method that converts an entity to a DTO.

Spring Boot

public static UserDTO fromEntity(UserEntity entity) {
    return new UserDTO([1]);
}

Drag options to blanks, or click blank then click option'

Aentity.convertToDTO()

Bentity.getUsername()

Centity.toDTO()

Dentity

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a field value instead of the whole entity to the constructor.

Calling non-existent methods on the entity.

The constructor expects a UserEntity object, so pass entity directly to fix the error of passing a method result like a String from getUsername().

4fill in blank

hard

Complete the code to complete the method that converts a list of entities to a list of DTOs using streams.

Spring Boot

public static List<UserDTO> fromEntityList(List<UserEntity> entities) {
    return entities.stream()
        .map(entity -> new UserDTO(entity))
        .collect(Collectors.[1]());
}

Drag options to blanks, or click blank then click option'

BtoList

CtoSet

DtoCollection

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a method on the entity inside the constructor call.

Using Collectors.toSet() when a list is expected.

The constructor expects the whole entity, so no method call is needed inside the parentheses (blank 1 is empty). The stream collects to a list, so Collectors.toList() is correct.

5fill in blank

hard

Fill all three blanks to complete the code for a manual mapping method from DTO to entity.

Spring Boot

public UserEntity toEntity() {
    UserEntity entity = new UserEntity();
    entity.set[1](this.[2]);
    entity.setEmail(this.[3]);
    return entity;
}

Drag options to blanks, or click blank then click option'

AUsername

Busername

Cemail

DEmail

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect casing in setter method names.

Using wrong field names from the DTO.

The setter method uses PascalCase for the field name: setUsername. The DTO field is username (camelCase). The email field is accessed as email in the DTO and set via setEmail in the entity.