Creating Movie repository and controller classes

Movie repository interface

Start by creating a new file called MovieRepository.java in the src/main/java/com/example/appspringdata directory, choose interface as the type, and extend it to match the following:

import org.springframework.data.neo4j.repository.Neo4jRepository;

interface MovieRepository extends Neo4jRepository<Movie, String> {
}

Spring Data provides repository extensions for many of its supported projects. They include methods and functionality specifically designed and optimized for the data store. In this case, you extend the Neo4jRepository interface. The first type parameter is the domain class that the repository will be working with, and the second type parameter is the type of the identifier for that domain class. In this case, the Movie domain class is the entity you want to return and the String type is its identifier.

Spring Data Neo4j also implements a few standard methods, such as save, findById, findAll, and deleteById. This is why you don’t need to define queries and methods to start out. You will see how to define custom implementations later in this course.

Moving on to the controller class, you will expose the query results with an API.

Movie controller class

Open the src/main/java/com/example/appspringdata directory and create a new class file called MovieController.java. Then add code for the following:

Completed code is available below to check your own work.

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.Optional;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@RestController
@RequestMapping("/movies")
public class MovieController {
    private final MovieRepository movieRepo;

    public MovieController(MovieRepository movieRepo) {
        this.movieRepo = movieRepo;
    }

    @GetMapping
    Iterable<Movie> findAllMovies() {
        return movieRepo.findAll();
    }

    @GetMapping("/{movieId}")
    Optional<Movie> findMovieById(@PathVariable String movieId) {
        return movieRepo.findById(movieId);
    }
}

You created a standard Spring MVC controller class, annotating it with @RestController to handle requests and responses and @RequestMapping to handle requests at the /movies endpoint. Injecting the repository interface allows access to call any repository methods, with the constructor taking a MovieRepository instance as a parameter. This is called dependency injection and is a standard practice in Spring applications.

You defined two methods to handle requests. The first method is annotated with @GetMapping and will handle requests to the /movies endpoint. It calls one of the out-of-the-box methods that Spring provides, the derived findAll method and returns a list of movies. The second method will handle requests to the /movies/{movieId} endpoint, including a path variable in the URL for a distinct movie id. It calls the derived findById method on the repository (passing in the path variable value) and returns the results.

Check Your Understanding