SpringBoot : Spring Data JPA - One To Many & Join Query | Example | Java Techie 

Yes Mohammad , correct am also new to this ide so , np going forward will use more shortcuts

lol..just target that parent package and then ctrl+n.. write the class name and edit the package name.

Yes Rajdeep you are correct I didn't notice this .thanks I will check and update you

Awesome, thank you :)

How it will show same customer with different json could you please mention the scenario

Yes we can

We can do in same way

Please go through my code and try to find out difference

Configure Lombok in your IDE

@@Javatechie I thank you very much for the quick answer and the solution I wish you a very big success my teacher I am very happy thank you once again

@@sediksedik7948 cool buddy 🙂

Yes why not

Then you need to create parameter constructor and exclude id from constructor

Yes why not

P P

Even helped me .. i was searching for this..

Hi Bala , What you are trying and in which api call you are getting null pointer exception If you share me code directly how can i identify the issue

Please debug and let me know which exact line giving NPE

Why two persons can't buy same product . Product id should be different right ?

Because in the product table product ID is primary key and customer ID is foreign If two person buys same product then it will throw an error Because customer ID is number it can occupy only one number And if same product is bought by another customer it can't create another row of same product ID in product table

Ok bidirectional I will do and share codebase with community Because I don't want to create video with duplicate content 🙏

Why it will fail ? It should add new entry in product table with mapped customer id

Change the id and try to persist the data

It seems because of corrupted data .can you please Remove hibernate sequence table from the dB then try it again

I didn't write getter and setter because am using Lombok . Please configure Lombok in your IDE , it will resolve your issue

Thanks buddy

@@Javatechie do you have one to one tutorial too?

Can you share your entity structure

Please configure Lombok in your IDE

Whatever I'm here understanding him from past 4 years he is good at what he is saying. English

Mohammad this is one to many example only please cross verify once

Never tried that

If it's microservice architecture then I would say this is such a bad practice

@@Javatechie ok....any recommendation then?

Check the annotation part

Hi buddy you are correct . Always I mentioned same that use service layer even I used few of my video also .but this is a demo Vedio and to save your time usually I follow this approach

Please restart your application

dto - data transfer object

No you need to write join query for all information you are expecting

Have you configured Lombok in your ide? If not please configure it

Yes @ToString you can ignore it's already there in @Datq

It should work it doesn't relay on variable name if you named it as topics then make sure to send topics as a key in json

yes i'm sending the same name in the request also, but not sure why its not working. and also one thing i'm not getting java.lang.IllegalArgumentException. but topics entity data is not storing my request is { "course":{ "course_id": 1, "course_name": "spring", "topic":[ { "topic_id": 1, "name": "java", "importance": "high", "description": "Core Java" }, { "topic_id": 2, "name": "mysql", "importance": "high", "description": "mysql basics" } ], "rating": 8, "prize": 3000 } } but i'm getting { "course_id": 1, "course_name": "spring", "topics": null, "rating": 8, "prize": 3000 } in response even i don't see any data in topic table

Me too

Check the annotations defined in entity class and it's import statement

Since this is one to many we can use same payload to add N number of products specific to a customer

Yes update is not a big deal , Just get the existing object by id then copy input object data to existing one and save it .

Not yet started buddy

@@Javatechie please start soon sir.. i would like to join

Please check my spring data jpa tutorial

@@Javatechie okey Ty :D

Yes but which entity is your parent you need to always add query on that repo

Configure Lombok in your IDE

Thank you so much buddy for your word . Could you please share the @Query annotations where you have write ✍️

@@Javatechie I have written it in an interface extending CrudRepository e.g : interface Xrepository extends CrudRepository{ @Query(" ") getInfo(){} } do you need the query as well? its actually a join of 3 entities, returning 3 attributes from 3 tables which I am mapping to a DTO.

What is the query, if you don't mind can you share your GitHub link to javatechie4u@gmail.com

Could you please share your entity structure

What error you are getting

@@Javatechie Error creating bean with name 'orderController': Unsatisfied dependency expressed through field 'customerRepository'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'customerRepository' defined in com.sravan.jpa.Repository.CustomerRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Invocation of init method failed; nested exception is org.springframework.data.repository.query.QueryCreationException: Could not create query for public abstract java.util.List com.sravan.jpa.Repository.CustomerRepository.getOrderDetails()! Reason: Validation failed for query for method public abstract java.util.List

@id annotation not working ? Try to insert id manually and let me know

Sorry @@Javatechie something wrong/extra line in the application.properties file i copied from another repo. I changed your's property file to postgres its woking now

Cool 😎

If there is no relationship between entity then why we need join first of all ? Yes as per your join query expected return value you need to create corresponding dto . It doesn't matter whether you are using native query or hql or jpql

@@Javatechie I tried with this but didn't work. @Query(value="SELECT new com.doc.importexport.dto.FirmHelper(f.firm_Id, f.firm_Name, f.firm_Registration_Number, f.proprietor_Name, f.firm_Address, f.proprietor_Contact, f.bank_Name, f.tt_Dap_Number, f.tt_Date, f.tt_Dap_Amount, f.application_Date,f.invoice_No, f.invoice_Date, f.bl_No, f.bl_Date, f.shipped_On_Date, f.revenue_Status, f.verification_Level, f.sender_Name, f.request_Date_Nepali, f.request_Send_By, f.assistant_Verification,f.assistant_Verification_Date, f.officer_Verification, f.officer_Verification_Date, f.director_Verification, f.director_Verification_Date, c.currency_Type, co.custom_Office_Name, pm.payment_Type, sp.sea_Port_Name, f.firm_Document, f.revenue_Amount, f.revenue_Voucher, f.request_Sender_Id) FROM Firm f, Sea_Port sp, Currency c, Custom_Office co, Payment_Method pm WHERE f.payment_Method_Id=pm.payment_Method_Id AND f.seaport_Id=sp.seaport_Id AND f.custom_Office_Id=co.custom_Office_Id AND f.currency_Id=c.currency_Id AND f.firm_Id=?1", nativeQuery = true) public FirmHelper getFirmDetailsByFirmId(int firmId);

Please configure Lombok in your IDE otherwise manually add getter and setter method

@@Javatechie alright, thanks for the response.

Hey Darshan it's just demo for spring jpa association mapping not hibernate tutorial. Do let me know if you want me to cover this as a separate session

@@Javatechie Yes Please do one video on all enums which are present in Hibernate, JPA, and Spring frameworks, spring boot . I searched for these enum types nobody did videos on this. If possible kindly do a few videos on all enum types

@Darshan Raut very nice question. beginners are expecting this type of question. We should know how to use them, where to use them, and scenarios they are using ...etc

I think you scan write native SQL with @query tag

@@AlhambraDream Yea, but that's native and database dependent. Anyways I learnt how to do joinings and other complex operations using JPA queries now.

@@ShinAkuma how?

Can you please share any other approach

It won't override instead it should add a new entry

@@Javatechie sir I have implemented it using course and students. In that multiple course can have same student. As we need to mention the primary key in spring boot while creating table so it won't allow repetation of the student. The foreign key(course_id) is getting overriden in the student table.

Please do cross verify with my code which I shared in GitHub link mentioned in video description

Yes agreed!

Please configure Lombok in your IDE

@@Javatechie okay thankyou

After correcting the MySQL dialect property it got fixed org.hibernate.dialect.MySQL5Dialect

Github link mentioned in video description

Dto is just to capture your request and response attribute but entity is the real value which will persist to your database

@@Javatechie Thanks and why is the advantage of capturing the request and response in dto way instead of the entity itself?

Yes we can update but how you will find out duplicate record ? You need to compare somewhere right ?

You can do that Simple just add show.sql=true in application.properties file .

Can you share your entity class?

@@Javatechie @Entity @Table(name = "Student") public class Student extends User { @OneToMany(targetEntity = Appointment.class ,cascade={CascadeType.MERGE,CascadeType.REFRESH}) @JoinColumn(name = "appointment_id",referencedColumnName = "id") private List listOfAppointment; .... } @Entity public class Appointment { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.AUTO) private long appointmentID; .... }

Why you extends from user class ?

@@Javatechie because there are other types of users, i.e students and lecture assistants. Is that the causd of the problem?

Yes , then go for inheritance mapping