Projection
Learn about the concept of projection and incorporation methods provided by Spring Data.
We'll cover the following...
What is projection?
Projection refers to a mechanism that allows selective retrieval of specific data fields from a database query result. By defining a projection, developers can retrieve just the required fields, improving performance and reducing unnecessary data transfer, resulting in more efficient data retrieval operations. The query methods in repositories of Spring Data usually return one or more instances of the defined POJO. However, Spring Data also lets us create projections based on the particular attributes of our POJOs.
Projection using class
We can declare a class with getter methods on the properties for the projections and use the class as the return type in the repository query method. The underlying Spring Data query generation mechanism will consider the class to be the data transfer object (DTO) and execute the query with the projection to only ...