Reading-notes

how to work with relationships between entities in Spring Data REST.
1. One-to-One Relationship
2.1. The Data Model
Let’s define two entity classes Library and Address having a one-to-one relationship, using the @OneToOne annotation. The association is owned by the Library end of the association.
The @RestResource annotation is optional and can be used to customize the endpoint.
We must be careful to have different names for each association resource. Otherwise, we will encounter a JsonMappingException with the message: “Detected multiple association links with same relation type! Disambiguate association”.
The association name defaults to the property name and can be customized using the rel attribute of @RestResource annotation.
The @RestResource annotation is optional and can be used to customize the endpoint.
We must be careful to have different names for each association resource. Otherwise, we will encounter a JsonMappingException with the message: “ Detected multiple association links with same relation type! Disambiguate association”. The association name defaults to the property name and can be customized using the rel attribute of @RestResource annotation.
We can resolve this by specifying a different value for the rel attribute or by omitting the RestResource annotation so that the resource name defaults to secondaryAddress.

2.2. The Repositories :

In order to expose these entities as resources, for ex :creat interface library etends CrudRepository:
public interface LibraryRepository extends CrudRepository<Library, Long> {} .
public interface AddressRepository extends CrudRepository<Address, Long> {} .

2.3. after that u are :

Creating the Resources :

by adding alibrary instance to work , The API returns the JSON object . double-qoute character inside the string represent JSON body at windows . after that the resbonse will received with association resourse has been expoed at liprary endpoint .

so before we creating the association we will send GET request to the endpoit that will return empty object . Now the result of the POST request is a JSON object .

Now ..

Creating the Associations :

After persisting both instances, we can establish the relationship by using one of the association resources. …To remove the Associations , we can call the endpoint with DELETE method, making sure to use the association resource of the owner of the relationship.

what

One-to-Many Relationship analysis !!

In systems analysis, a one-to-many relationship is a type of cardinality that refers to the relationship between two entities A and B in which an element of A may be linked to many elements of B, but a member of B is linked to only one element of A. For instance, think of A as books, and B as pages.

and there is

The Data Model..

To exemplify a one-to-many relationship.

also

we need creat Repository ..

and after that dealing with this data , how ever there is alot thing to do also , like Testing the One-to-One Relationship , Testing the One-to-Many Relationship , and thats it :)

Spring MVC Test Configuration

Let’s now introduce how to configure and run the Spring enabled tests.

Enable Spring in Tests with JUnit 5

by adding the @ExtendWith annotation to our test classes and specifying the extension class to load.

The WebApplicationContext Object

WebApplicationContext provides a web application configuration. It loads all the application beans and controllers into the context.

Verify Test Configuration.after all .

WebApplicationContext and MockMvc object creation, which played an important role in calling the endpoints of the application.
Looking further, we covered how we can send GET and POST requests with variations of parameter passing and how to verify the HTTP response status, header, and content.
As a closing remark, we did also evaluate some limitations of MockMvc. Knowing those limitations can guide us to make an informed decision about how we’re going to implement our tests.