Develop the Mock Service

We will only see how to manage the join between User and the Group. The usual create, read, delete, and edit operations for the User as well as Group have the same implementation as discussed in earlier chapters. For your reference, the link to the entire source code has been given in the Appendix should you face any issues understanding the flow.

add function

The mock service will interact with an in-memory database to save the data, which will be consumed by the mock user interface. We will start with the add functionality. We have a list of UserGroupDto. With every new occurrence, one instance of UserGroupDto containing a UserDto and a GroupDto is added to the list. A Singleton design pattern by means of enum is followed for the in-memory database implementation. The identifier field starts at one and progresses by one for every new count.