Spring boot applicaiton for crud operation
This is a demo application which demonstrates basic crud operation with RESTful web services, Spring boot, Spring MVC, JPA, Connect to MYSQL db, Spring Security Sign up, Sign in, JSON web token (JWT) based authentication.
In this demo project we are trying to achieve basic Crud operation for rest APIs and we have implemented number of technologies provided by Spring boot framework.
- JWT
- Actuator : for monitoring APIs.
- Content negotiation : providing API response both JSON and XML format.
- HATEOAS : providing next resource link automatically
- Swagger : documentaion format for restful services
- paginaiton with JpaRepository
The basic architecture of this application is given below.
The EER model diagram as follows
The diagram for Authentication Manager which is responsible for validate authenticaiton from db.
To make best use of spring boot application, it's mandatory to understand following concepts
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Optional : Return type Optional is a new container type that wraps a single value. It is used to represent a value is present or absent. The main advantage of this new construct is that No more too many null checks and NullPointerException.
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@RepositoryRestResource(exported = false) disable hal features
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JsonBackReference
- This annotation basically says that posts will not be part of the JSON
- returned for tag (but each post will contain list of its tags in the
- response). If the post was a part of the list then the program would fetch
- the post's tags, which would then make the program fetch the post again
- and again until we’d get a StackOverflowException.
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@Service : hold the business logic and call method in repository layer
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@Bean : create instance of object
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@Autowire : This is a dependency, I want actual object/instance, Pls create dependency for me. you cant @autowire any class if it not marked with @component
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@Component: It means that Spring framework will autodetect these classes for dependency injection when annotation-based configuration and classpath scanning is used.To make spring annotonation aware that It's kinda like "I may need object of this class. @Component is a class level annotation where as @Bean is a method level annotation.
VS @Configuration annotation indicates that a class declares one or more @Bean methods and may be processed by the Spring container to generate bean definitions and service requests for those beans at runtime.
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CSRF - Cross-Site Request Forgery vulnerability allows an attacker to force a logged-in user to perform an important action without their consent or knowledge.
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@Restcontroller - response body + controller --> return JSON/XML, responsible for handling all the incoming client request and delagates it to appropriate service method.
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@controller - returns mapping AKA view as html/jsp
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JWT - json web token - used for api authentication
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@Repository - This is to indicate that the class defines a data repository.
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ResponseEntity is meant to represent the entire HTTP response. You can control anything that goes into it: status code, headers, and body.
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@ResponseBody is a marker for the HTTP response body and @ResponseStatus declares the status code of the HTTP response.
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Cascading - Entity relationships often depend on the existence of another entity — for example, the Person–Address relationship. Without the Person, the Address entity doesn't have any meaning of its own. When we delete the Person entity, our Address entity should also get deleted.
Cascading is the way to achieve this. When we perform some action on the target entity, the same action will be applied to the associated entity. -
DTO is an abbreviation for Data Transfer Object, so it is used to transfer the data between classes and modules of your application. DTO should only contain private fields for your data, getters, setters and constructors. It is not recommended to add business logic methods to such classes, but it is OK to add some util methods.
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DAO is an abbreviation for Data Access Object, so it should encapsulate the logic for retrieving, saving and updating data in your data storage (a database, a file-system, whatever).
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Dao uses Spring JPA to perform DB operations whereas DaoImpl has implementation with Hibernate for performing DB operations.
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JpaRepository extends PagingAndSortingRepository which in turn extends CrudRepository. Their main functions are: CrudRepository : mainly provides CRUD functions. PagingAndSortingRepository : provides methods to do pagination and sorting records. JpaRepository : provides some JPA-related methods such as flushing the persistence context and deleting records in a batch.
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FetchType.Lazy : to avoid recursion, unless u call it, it will not fetch the details.
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Maven : build & dependency management tools
maven let you declare all the dependency that you want in a single file. you dont have to download the file and add in your class path, you just mention the jars that you need are into this file which is called pom.xml. In this file contains list of dependencies that maven needs to know. Then you run a maven command and maven gonna look at your dependencies and find all the dependencies that app needs to run & it goes to that repository (https://mvnrepository.com/) to get all the jars.
Procedure to test APIs
1- for SignUp (post) url - http://localhost:8083/api/auth/signup in the body { "username" : "hos", "email": "hosgmail@sdf.com", "password" : "aaaaaa", "role" : ["admin"] }
2- for SignIn (post) url - localhost:8083/api/auth/signin in the body { "username" : "hos", "password" : "aaaaaa" }
3- for getting lists of users/pages/posts/tags (Get)
url - http://localhost:8083/users
url - http://localhost:8083/pages
url - http://localhost:8083/posts
url - http://localhost:8083/tags
paginaiton with JpaRepository -
url - http://localhost:8083/tagsbypagination?size=5&page=0
url - http://localhost:8083/usersbypagination?size=5&page=0
url - http://localhost:8083/pagesbypagination?size=5&page=0
url - http://localhost:8083/postsbypagination?size=5&page=0
Dont forget to add jwt token in the authorization header before calling any API request which you will get it during SignIn process and create a DB called mydb in mysql workbench / shell, change application.properties as needed.
Docker
Now we will learn how to dockerize spring boot application, building image by using docker file and at the end launching spring boot application with mysql db all together by using docker compose.
Let's have some basic understanding about docker
Let's see what docker host is consists of
So, in order to run this spring boot application :
1- at first, we need to create .jar file of this application. we can type "mvn clean package -DskipTests" in CMD to get .jar.
2- then after creating .jar file now we have to create the image of the application so we can type "docker build -t diganto007/user-post-api:0.0.1-SNAPSHOT ."
3- we have our image for spring boot application is ready to deploy but instead of launching spring boot application and mysql db seperately, we can use docker-compose to launch both of them together. A docker-compose.yml file has been written and customized to serve the purpose. So now we can just type "docker-compose up" in CMD.
So what is the difference between dockerfile and docker compose ?
A Dockerfile is a simple text file that contains the commands a user could call to assemble an image whereas Docker Compose is a tool for defining and running multi-container Docker applications. Docker Compose define the services that make up your app in docker-compose.yml so they can be run together in an isolated environment.
Pls check the youtube video for better understanding how to dockerize your application. (https://www.youtube.com/watch?v=HL0s3YGmjew)