JModelMapper

Mar 24, 24

A simple JavaBean mapper which uses reflection and DFS ( Depth First Search ) algorithm to map homegenous or non homogenous source and destination objects

JModel Mapper

JModel Mapper is an open source library used to map simple to deep object nesting with similar object data structure without the need of accessors or mutators

Maven

<dependency>
    <groupId>de.johnsoneyo</groupId>
    <artifactId>jmodel-mapper</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

Kotlin

  • Under Development

Assumptions

  • Mapping of Data fields between two objects that have homogeneous fields and data type happens out of the box with zero configuration
  • Custom field mapping is targeted at intentional naming or chosen by the user or client
  • Destination classes
    • Has a non argument constructor and doesn’t require immutable creation, required for no argument class object construction.
    • Has getter fields for returning the values atleast ( no mandatory )

Limitations

  • No Kotlin or Scala equivalent

Usage

  • Create bean instance or a singleton 
    static final JModelMapper modelMapper = new JModelMapper();

Supply source object and destination class

  Person expected = new Person(name, age, sex, List.of(new Person.Address("test-street-1", "test-zipcode-1",
        new Person.Address.ExtraInfo("100010000.0000")),
        new Person.Address("test-street-2", "test-zipcode-2", new Person.Address.ExtraInfo("test-extra-info"))),
        Map.of("key", "value"));

PersonDto actual = modelMapper.map(expected, PersonDto.class);
  • Use Type Transformers if you want to map same name field to different data type

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.OffsetDateTime;

/**
 * Type Adapter Example
 */
public class LocalDateTimeToOffsetDateTimeTypeAdapter implements TypeAdapter<LocalDate, OffsetDateTime> {

  /**
   * 
    * @param localDateTime input parameter to be converted
   * @return
   */  
  @Override
  public OffsetDateTime convert(LocalDateTime localDateTime) {
    Objects.requireNonNull(localDateTime);
    ZoneOffset offset = OffsetDateTime.now().getOffset();
    OffsetDateTime offsetDateTime = localDateTime.atOffset(offset);
    return offsetDateTime;
  }
}

Decorate class field

        @TransformToType(typeAdapter = LocalDateTimeToOffsetDateTimeTypeAdapter.class)
        OffsetDateTime localDateTime;
  • Use ClassFieldMapping for custom field maps of the same type
## Source Class defined with id parameter 
 static class Request {
        String requesterId;
        String id;

        public Request(String requesterId, String id) {
            this.requesterId = requesterId;
            this.id = id;
        }

        public Request(String requesterId) {
            this.requesterId = requesterId;
        }
    }
    

static class RequestDto {
    
  UUID requesterId;

  /**
   * Destination field identifier mapped to {@link Request#id }
    */
  @ClassFieldMapping(fields = { @SourceFieldMapping(sourceField = "id") })
  String identifier;

  public RequestDto() {
  }

  public UUID getRequesterId() {
    return requesterId;
  }

  public String getIdentifier() {
    return identifier;
  }
}