In this lesson, you will learn how to write custom methods and queries that take parameters to retrieve data from the database.
Defining a custom repository method with parameters
You can also define custom methods that take parameters. For instance, what if you wanted to find all of the movies that a specific person acted in.
In the src/main/java/com/example/appspringdata folder, open the MovieRepository.java and define another custom method shown below.
@Query("MATCH (m:Movie)<-[r:ACTED_IN]-(p:Person {name: $name})" +
"RETURN m, collect(r), collect(p);")
Iterable<Movie> findMoviesByPerson(String name);Next, add a new method in the MovieController class that calls this method, passing in a RequestParam for a name.
//new method to call the custom `findMoviesByPerson()` method
@GetMapping("/person")
Iterable<Movie> findMoviesByPerson(@RequestParam String name) {
return movieRepo.findMoviesByPerson(name);
}Full code for the MovieRepository and MovieController classes is available in the dropdown below.
Click to reveal the completed MovieRepository and MovieController class code
import org.springframework.data.neo4j.repository.Neo4jRepository;
import org.springframework.data.neo4j.repository.query.Query;
interface MovieRepository extends Neo4jRepository<Movie, String> {
@Query("MATCH (m:Movie)<-[r:ACTED_IN]-(p:Person)" +
"RETURN m, collect(r), collect(p) LIMIT 20;")
Iterable<Movie> findMoviesSubset();
@Query("MATCH (m:Movie)<-[r:ACTED_IN]-(p:Person {name: $name})" +
"RETURN m, collect(r), collect(p);")
Iterable<Movie> findMoviesByPerson(String name);
}
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;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.RequestParam;
@RestController
@RequestMapping("/movies")
public class MovieController {
private final MovieRepository movieRepo;
public MovieController(MovieRepository movieRepo) {
this.movieRepo = movieRepo;
}
@GetMapping()
Iterable<Movie> findAllMovies() {
return movieRepo.findMoviesSubset();
}
@GetMapping("/{movieId}")
Optional<Movie> findMovieById(@PathVariable String movieId) {
return movieRepo.findById(movieId);
}
@PostMapping("/save")
Movie save(@RequestBody Movie movie) {
return movieRepo.save(movie);
}
@DeleteMapping("/delete")
void delete(@RequestParam String movieId) {
movieRepo.deleteById(movieId);
System.out.println("Deleted movie with movieId: " + movieId);
}
@GetMapping("/person")
Iterable<Movie> findMoviesByPerson(@RequestParam String name) {
return movieRepo.findMoviesByPerson(name);
}
}In the repository interface, you have a new method called findMoviesByPerson() that takes a String parameter called name. You annotate the method with @Query and provide a Cypher statement that will return all of the movies that a person acted in, using the $name parameter to match the Person with the name provided in the parameter.
In the controller, there is a new method called findMoviesByPerson() that calls the custom repository method and passes in the name from a URL parameter. You also need a @GetMapping annotation to map the method to /movies/person.
Testing the findMoviesByPerson() custom method
Just as before, you can test the new method by running the application and calling the /movies/person endpoint with a name parameter to search. You should see a response with all of the movies that the person node is connected to, each with their ACTED_IN relationships and Person nodes.
curl 'localhost:8080/movies/person?name=Robin%20Williams'
Feel free to run the provided query in the right-hand tab to see the results there as well. You can also try passing in different actors' names to the request and see the results.
Summary
In this lesson, you learned how to write your own custom methods and queries to retrieve data from the database.
Next, you will complete a challenge that builds upon that skill to create custom queries and methods for writing data to the database.