Table of contents

Introduction

UserResource to use JPA - Updating POST and DELETE methods

2.1.

Step 1: Modify

2.2.

Step 2: Delete

2.3.

Step 3: Postman Application

2.4.

Step 4: POST Request

2.5.

Step 5: Selection

2.6.

Step 6: Input

2.7.

Step 7: Exception

2.8.

Step 8: Resolution

2.9.

Step 9: POST Request Again

Frequently Asked Questions

3.1.

How can I remove several records at once from JPA?

3.2.

What does the JPA delete query return?

3.3.

What does API's Delete method do?

3.4.

Can POST be used to update data?

3.5.

Which technique does JPA employ when doing a delete operation?

Conclusion

Last Updated: Mar 27, 2024

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UserResource to use JPA - Updating POST and DELETE methods

Author Rasha Abdul Khader

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Introduction

A SpringBoot JPA specification is used to manage relational data in Java applications. It enables data access and persistence across a Java object or class and a relational database. Object-Relation Mapping (ORM) is used by JPA (ORM). It's a collection of interfaces. It additionally offers a runtime EntityManager API for executing queries and transactions on the objects against the database. It employs the object-oriented query language JPQL, which is platform neutral (Java Persistent Query Language). A framework is not JPA. Any framework can use it to implement the idea it describes.

UserResource to use JPA - Updating POST and DELETE methods

UserResource to use JPA for Updating POST and DELETE methods

This part will convert the deleteUser() method and the createUser() method to JPA. Let's update UserJPAResource.java with the necessary adjustments.

Step 1: Modify

Modify the service provided by the deleteUser() function.

Step 2: Delete

UserRepository's delete() method does not return anything. Delete the return type.

@DeleteMapping("/jpa/users/{id}") 
public void deleteUser(@PathVariable int id) 
{ 
userRepository.deleteById(id); 
} 
It throws an exception if it is unsuccessful.

Step 3: Postman Application

Send a DELETE request using the Postman application and the URL http://localhost:8080/jpa/users/1 .

Status: 200 OK denotes that the record has been deleted successfully.

The URL http://localhost:8080/jpa/users/1 should be used to make another DELETE request. "No entity with id 1 exists" is the message returned.

{ 
"timesatmp": "2022-09-27T13:35:02", 
"message": "No class com.javatpoint.rest.webServices.restfulwebservices.user. User entity with id 1 exists! ", 
"details": "uri=/jpa/user/1" 
}

To create a user, we shall right away issue a POST request.

Step 4: POST Request

Send a POST request to http://localhost:8080/jpa/users using the specified URL.

Step 5: Selection

Make sure that application/json is selected for the Content Type when you click the Headers tab.

Step 6: Input

The user's name and Date Of Birth should be entered in the Body tab. The name Ravi has been input.

Step 7: Exception

By pressing the Send button, the ConstaintViolationException is thrown when we attempt to create a user.

Hibernation employs a sequence due to which the user entity's Id is a created value. The id of the row that Hibernate is attempting to insert is 1. It is in contrast with the information we currently know.

Step 8: Resolution

In order to resolve the conflict, change the Ids in the data.sql file by opening it.

insert into user values(101, sysdate(), "Ravi"); 
insert into user values(102, sysdate(), "Abel"); 
insert into user values(104, sysdate(), "Tia");

Step 9: POST Request Again

Publish a POST request once again. It displays Status: 201 Created as a result. The status indicates successful user creation.

Frequently Asked Questions

How can I remove several records at once from JPA?

To begin with, you must develop a JPA query method that returns all entries belonging to an ID. Then, you can use the deleteAll() action on the List.

What does the JPA delete query return?

A single JPQL query is created against the database using the @Query function. In contrast, the deleteBy methods do a read query before deleting each item individually. Additionally, the deleteBy method can provide a list of deleted entries, whereas the custom query only returns the total number of records that have been removed.

What does API's Delete method do?

The Web API's Delete action function will be implemented in this section. In the RESTful architecture, a record can be deleted from the data source by sending an HTTP DELETE request. Therefore, using Entity Framework, let's add an action method in our StudentController to remove an existing student record from the database.

Check out Entity Framework Interview Questions to know more about it.

Can POST be used to update data?

To update a resource, you can use POST, but you cannot use the resource's URL as the POST request.

Which technique does JPA employ when doing a delete operation?

To delete a record associated with a particular primary key, we may use the JPA method deleteById().

Conclusion

This blog demonstrates how to get UserResource to use JPA for Updating POST and DELETE methods.

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