extending MongoRepository - spring

Question

I'm new to spring and confused as to how autowiring works on an interface that extends MongoRepository
Here is the code:
App.java
package com.db.mongo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class App implements CommandLineRunner
{
#Autowired
private CustomerRepository repository;
public static void main( String[] args )
{
SpringApplication.run(App.class, args);
}
public void run(String... args) throws Exception {
// TODO Auto-generated method stub
repository.deleteAll();
repository.save(new Customer("Alice", "Smith"));
repository.save(new Customer("Bob", "Smith"));
System.out.println("Customers found with findAll():");
System.out.println("-------------------------------");
for (Customer customer : repository.findAll()) {
System.out.println(customer);
}
System.out.println();
System.out.println("Customer found with findByFirstName('Alice'):");
System.out.println("--------------------------------");
System.out.println(repository.findByFirstName("Alice"));
System.out.println("Customers found with findByLastName('Smith'):");
System.out.println("--------------------------------");
for (Customer customer : repository.findByLastName("Smith")) {
System.out.println(customer);
}
}
}
CustomerRepository
package com.db.mongo;
import java.util.List;
import org.springframework.data.mongodb.repository.MongoRepository;
public interface CustomerRepository extends MongoRepository {
public Customer findByFirstName(String firstName);
public List<Customer> findByLastName(String lastName);
}
Customer.java
package com.db.mongo;
import org.springframework.data.annotation.Id;
public class Customer {
#Id
public String id;
public String firstName;
public String lastName;
public Customer() {}
public Customer(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
#Override
public String toString() {
return String.format(
"Customer[id=%s, firstName='%s', lastName='%s']",
id, firstName, lastName);
}
}

Answer 1

if you are using spring data mongodb.It has the capability to create the query which are in your domain. The CrudRepository provides sophisticated CRUD functionality for the entity class that is being managed.for more details read here