Spring Boot + MongoDB

• 🐣Spring & SpringBoot, 🍃MongoDB

• Add

  • Spring Data MongoDB module - MongoDB Driver
  • Lombok
  • spring data web

• Add mongodb uri to application.yml

  • spring.data.mongodb.uri=

• RESOURCES

  • https://www.mongodb.com/resources/products/compatibilities/spring-boot

@Document

• We add the @Document annotation → table name
  • @Document annotation is used on a Java class that represents a single document, but its purpose is to map that class to a MongoDB collection (the name is a bit backwards)
  • the annotation describes the type of thing you are storing
  • “This Java class Student is a blueprint for a single document. I want you to store all objects of this type in a collection called students”
  • If the collection doesn’t exist (this case students, MongoDB will create it)
• An instance of your Student class = one document

@Document("students")
@Data  
@NoArgsConstructor  
@AllArgsConstructor  
public class Student {  
  
  @Id  
  private Integer rno;  
  private String name;  
  private String address;  
}

• @Id
  • specifies primary key in our MongoDB document
  • If we don’t do this the MongoDB will automatically generate an _id when creating the document

MongoTemplate class

• Part of the Spring Data MongoDB module
• a template class that acts as an abstraction layer over MongoDB operations and allows you to perform basic CRUD operations, as well as more complex queries and aggregations

MongoRepository interface

• Part of the Spring Data MongoDB module
• extends the CrudRepository & PagingAndSortingRepository interfaces
  • Spring Data JPA
• provides a higher-level abstraction over MongoDB operations than MongoTemplate, focusing on the repository pattern to work with data

public interface ItemRepository extends MongoRepository<GroceryItem, String> {
	
	@Query("{name:'?0'}")
	GroceryItem findItemByName(String name);
	
	@Query(value="{category:'?0'}", fields="{'name' : 1, 'quantity' : 1}")
	List<GroceryItem> findAll(String category);
	
	public long count();
	
	// basic CRUD methods provided
}

• @Query("{name:'?0'}")
  • requires a parameter for the query, i.e., the field by which to filter the query
• @Query(value="{category:'?0'}", fields="{'name' : 1, 'quantity' : 1}")
  • uses the category field to get a particular category’s items