DTO to Entity and Entity to DTO Conversion

In this blog post, I will share how to copy properties from a DTO object to an Entity object and then back from an Entity object to a DTO object.

DTO stands for Data Transfer Object and is a simple, Plain Old Java Object which contains class properties and getter and setter methods for accessing those properties.

In this tutorial, I will use the BeanUtils class provided by a Spring Framework, but another way to map objects will be to use ModelMapper.

import org.springframework.beans.BeanUtils

the use of BeanUtils is very simple. To copy properties from a source Java object to a target Java object, a simple static method is used:

BeanUtils.copyProperties(sourceObject, targetObject);

Note: when using the BeanUtils.copyProperties() method, class field names in the sourceObject must match the class field names in the destination object. Have a look at the example DTO and Entity classes below.

DTO Class

Let’s say we have the following DTO Java class

package com.appsdeveloperblog.app.ws.shared.dto;

import java.io.Serializable;

public class UserDto implements Serializable {

    private static final long serialVersionUID = 4865903039190150223L;
    private long id;
    private String firstName;
    private String lastName;
    private String email;
    private String password;
    private String encryptedPassword;
    private String userId;

 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    public String getFirstName() {
        return firstName;
    }

 
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

 
    public String getLastName() {
        return lastName;
    }

 
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

  
    public String getEmail() {
        return email;
    }

 
    public void setEmail(String email) {
        this.email = email;
    }

 
    public String getPassword() {
        return password;
    }

Entity Class

And let’s say we have the following entity class:

@Entity(name = "users")
public class UserEntity implements Serializable {

    private static final long serialVersionUID = 4865903039190150223L;
    @Id
    @GeneratedValue
    private long id;
 
    @Column(length = 50, nullable = false)
    private String firstName;

    @Column(length = 50, nullable = false)
    private String lastName;

    @Column(length = 100, nullable = false)
    private String email;

    @Column(nullable = false)
    private String encryptedPassword;
 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    public String getFirstName() {
        return firstName;
    }
 
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
 
    public String getLastName() {
        return lastName;
    }
 
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
 
    public String getEmail() {
        return email;
    }
 
    public void setEmail(String email) {
        this.email = email;
    }
 
    public String getEncryptedPassword() {
        return encryptedPassword;
    }
 
    public void setEncryptedPassword(String encryptedPassword) {
        this.encryptedPassword = encryptedPassword;
    }
}

Copy Properties from DTO to Entity

To copy properties from the above-mentioned DTO to an Entity object, we can use the following line of code:

UserEntity userEntity = new UserEntity();
BeanUtils.copyProperties(userDto, userEntity);

where:

• userDto is a source DTO object and
• userEntity is a target object.

And this is it! A very simple and very convenient way of copying properties from one bean to another.

BeanUtils – Ignore Certain Properties

When copying properties from an Entity object to a DTO object, sometimes, you might want to ignore certain properties. You can do it by using the following command:

BeanUtils.copyProperties(sourceObj, targetObj, "propertyToIgnoreA", "propertyToIgnoreB", "propertyToIgnoreC");

Just list the property names you want to ignore after the targetObj parameter.

Watch the following Spring Boot video tutorials, to learn more.