java - Conversion of DTO to entity and vice-versa

Question

I am using Spring MVC architecture with JPA in my web application. Where to convert data transfer object (DTO) to JPA entity and vice-versa, manually (that is, without using any framework)?

Answer 1

This is an old question with accepted answer but though to update it with easy way of doing it using model-mapper API.

<dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
    <version>0.7.4</version>
</dependency>

Using this API, you avoid manual setter & getters as explained in accepted answer.

In my opinion, both conversions should happen at controller with the help of private utility methods and using Java8 stream's map ( if a Collection of DTOs is exchanged ) like illustrated in this article.

It should happen at controller because DTOs are meant to be exclusive transfer objects. I don't take my DTOs further way down.

You code your service & data access layers on entities and convert DTOs to entities before calling service methods & convert entities to DTOs before returning response from controller.

I prefer this approach because entities rarely change and data can be added / removed from DTOs as desired.

Detailed model mapper configuration and rules are described here