GPT as Mentor & Coding Tool
Tags: java, ai, gpt
Published: 2024-06-02 13:00:37


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/lejrrw5qak3z7vatjmhf.jpg)

> **Summary**
> _Welcome to the first article in a series where I'm developing a pet project with GPT as my Java mentor and coding assistant. In this article, GPT helps me create a plan and writes five Spring Boot microservices, including controllers, services, repositories, entities, DTOs, mappers, table descriptions, and XML scripts for Liquibase._

Recently, I have often heard that artificial intelligence will soon leave non-exceptional programmers without jobs. In my blog, starting with this post, I will try to show you how a non-exceptional programmer can find a job with the help of ChatGPT. I will be using GPT as a Java mentor. It will help me design an application, select technologies, write APIs for each microservice, and draft a database description.

So, let's start with my prompt.

> My goal is to secure a position as a mid-level Java developer. To achieve this, I need to enhance my knowledge of several technologies. Therefore, I plan to develop a pet project for registering stray dogs. This is not a startup; it's an educational project that I aim to implement as quickly as possible.
> The users of the application will be:
> 1. Volunteers who can enter dogs into the database.
> 2. All other users can view this database.

> Any user will be able to send donations to any dog. Each dog's medical history, including vaccinations and sterilizations, will be tracked. The dog's profile will include photos, a number (as most dogs have colored tags with numbers, although not all do), and an approximate location and age. Admins should have the ability to send notifications to all users.
> I plan to use the following technologies: Spring Boot, Spring Security, Liquibase, Maven, REST API, Swagger, PostgreSQL, Hibernate, Redis, Kafka, Elasticsearch, Docker, CI/CD, Stripe or PayPal API, and AWS. I don't have much experience with Redis, Elasticsearch, Docker, CI/CD, Stripe or PayPal API, or AWS, but I'm fairly comfortable with the rest. You can suggest other technologies if necessary.
> I need to design the application architecture to easily add a microservice for image recognition in the future. This microservice will recognize dogs from photos and search for them in the database. Could you act as a Java mentor and suggest which microservices I should develop, and help me write APIs for each one?

GPT response:

> To structure your pet project efficiently, we'll focus on a microservices architecture that aligns with your goal of expanding your knowledge as a mid-level Java developer. We'll design the application to be scalable and ready to integrate future technologies, such as an image recognition microservice. Here's a step-by-step guide to the microservices architecture, the APIs you should implement for each microservice, and how to utilize the technologies you're interested in learning:
> ## Microservices Design and APIs

> **1. Dog Management Service**
> - _Purpose:_ Manages all dog-related information.
> - _Technologies:_ Spring Boot, Maven, PostgreSQL, Hibernate, Spring Security, Redis (for caching).
> - _APIs:_
>  - POST /dogs - Create a new dog profile.
>  - GET /dogs/{id} - Retrieve a dog's profile by ID.
>  - PUT /dogs/{id} - Update a dog's profile.
>  - DELETE /dogs/{id} - Delete a dog's profile.
>  - GET /dogs - List all dogs with filtering options.

> **2. Medical Records Service**
> - _Purpose:_ Manages medical histories of dogs.
> - _Technologies:_ Spring Boot, Maven, PostgreSQL, Hibernate.
> - _APIs:_
>  - POST /medical-records - Add medical record.
>  - GET /medical-records/{dogId} - Get medical records for a specific dog.
>  - PUT /medical-records/{id} - Update a medical record.
>  - DELETE /medical-records/{id} - Delete a medical record.

> **3. Donation Management Service**
> - _Purpose:_ Handles donations made to dogs.
> - _Technologies:_ Spring Boot, Maven, Stripe or PayPal API.
> - _APIs:_
>  - POST /donations - Make a donation.
>  - GET /donations/{dogId} - Retrieve donations for a specific dog.

> **4. Notification Service**
> - _Purpose:_ Sends notifications to users.
> -  _Technologies:_ Spring Boot, Kafka (for messaging).
> - _APIs:_
>  - POST /notifications - Send a notification.
>  - GET /notifications - List all notifications.

> **5. Search Service**
> - _Purpose:_ Provides advanced search capabilities across the dog database.
> - _Technologies:_ Spring Boot, Elasticsearch.
> - _APIs:_
>  - GET /search - Search dogs based on various criteria (e.g., name, location).

> **6. User Management Service**
> - _Purpose:_ Manages user accounts and roles.
> - _Technologies:_ Spring Boot, PostgreSQL, Spring Security.
> - _APIs:_
>  - POST /users - Register new user.
>  - POST /login - User login.
>  - GET /users/{id} - Get user information.
>  - PUT /users/{id} - Update user information.

> ## Future Expansion: Image Recognition Service
> - _Purpose:_ To recognize dogs from uploaded photos and match them against the database.
> - _Technologies:_ Potential use of AI/ML libraries or platforms.

> ## Project Execution and Learning Plan

> **Phase 1: Setup and Basic CRUD Operations**
> - Setup Maven projects for each microservice.
> - Implement basic CRUD operations for Dog Management and Medical Records Services.

> **Phase 2: Implement Additional Services**
> - Develop Donation Management, Notification, and User Management Services.
> - Begin integrating Redis for caching commonly retrieved data in the Dog Management Service.

> **Phase 3: Advanced Features and Deployment**
> - Integrate Elasticsearch in the Search Service.
> - Setup Docker containers for each microservice.
> - Establish a CI/CD pipeline using Jenkins or GitHub Actions.
> - Deploy services to AWS.

> **Phase 4: Third-Party Integration and Testing**
> - Integrate Stripe or PayPal for processing donations.
> - Thoroughly test each service and ensure all parts work together seamlessly.

> This approach will not only help you learn each technology but also give you a comprehensive understanding of how modern applications are structured and scaled using microservices. By documenting all APIs with Swagger, you'll ensure that your application is maintainable and understandable.

This looks great; he wrote the API for me. I'll probably need to finish it up and maybe redo some parts, but it's awesome! Now I need to think about the database tables. Or wait, why should I? Let GPT handle that.

> Can you describe the database tables I need to create?

GPT response:

> For your pet project on managing stray dogs, let's design the database schema to support your application's functionality efficiently. We'll consider five primary areas of functionality: dog management, medical records, donations, notifications, and user management. Here's a suggested schema for each:

> **1. Dog Management**

> This service will manage dog profiles, which include their basic information, photos, and location.

> Table: **Dogs**

> - _dog_id_ (Primary Key): Unique identifier for each dog.
> - _name_ (VARCHAR): Name of the dog.
> - _age_ (INTEGER): Age of the dog.
> - _location_ (VARCHAR): Approximate location where the dog is usually found.
> - _photo_url_ (VARCHAR): URL to the dog's photo.

> **2. Medical Records**

> This service will track medical histories, including vaccinations and sterilizations.

> Table: **Medical_Records**

> - _record_id_ (Primary Key): Unique identifier for each record.
> - _dog_id_ (Foreign Key): Linked to the Dogs table.
> - _description_ (TEXT): Description of the medical event.
> - _event_date_ (DATE): Date when the event occurred.
> - _type_ (VARCHAR): Type of medical event (e.g., vaccination, sterilization).

> **3. Donation Management**

> This service will handle donations made to each dog.

> Table: **Donations**

> - _donation_id_ (Primary Key): Unique identifier for each donation.
> - _dog_id_ (Foreign Key): Linked to the Dogs table.
> - _user_id_ (Foreign Key): Linked to the Users table.
> - _amount_ (DECIMAL): Amount of money donated.
> - _date_ (DATE): Date when the donation was made.

> **4. Notification Service**

> This service will store notifications intended to be sent to users.

> Table: **Notifications**

> - _notification_id_ (Primary Key): Unique identifier for each notification.
> - _message_ (TEXT): Notification message content.
> - _date_sent_ (DATE): Date when the notification was sent.

> **5. User Management**

> This service will manage user accounts and their roles (volunteers, admins).

> Table: **Users**

> - _user_id_ (Primary Key): Unique identifier for each user.
> - _username_ (VARCHAR): Username for the account.
> - _password_ (VARCHAR): Hashed password for security.
> - _email_ (VARCHAR): User's email address.
> - _role_ (VARCHAR): Role of the user (e.g., volunteer, admin).

> **Foreign Keys and Indexing**

> - Ensure that _dog_id_ in **Medical_Records** and **Donations** is a foreign key linked to the **Dogs** table.
> - Ensure that _user_id_ in **Donations** is a foreign key linked to the 
**Users** table.
> - Consider adding indexes to commonly searched fields like _dog_id_ in 
**Dogs**, _user_id_ in **Users**, and _event_date _ in **Medical_Records** to improve query performance.

> **Considerations for Scalability and Performance**

> - Use **PostgreSQL** for its robustness and support for complex queries and relationships.
> - Consider implementing **caching mechanisms** for frequently accessed data like dog profiles using Redis.
> - Optimize your schema and queries as needed based on the actual data access patterns you observe during development and initial testing.
> This schema provides a solid foundation for your application, ensuring that all necessary data is captured efficiently and is easily accessible via your planned APIs.

Great. Now I'd like GPT to generate Liquibase changelogs in XML format so I don't have to write them myself.

> Generate the appropriate Liquibase changelogs in XML format for each microservice

GPT response:

> To create Liquibase changelogs in XML format for each microservice, I'll outline the changelogs for the database schema we discussed. Each changelog will be crafted for specific parts of the application, facilitating modular deployment and easier management.
> ## 1. Dogs Management Service
> File: **db.changelog-dogs.xml**

```
<?xml version="1.0" encoding="UTF-8"?>

<databaseChangeLog
    xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
        http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.8.xsd">

    <changeSet id="1" author="your_username">
        <createTable tableName="dogs">
            <column name="dog_id" type="serial" autoIncrement="true">
                <constraints primaryKey="true" nullable="false"/>
            </column>
            <column name="name" type="varchar(255)"/>
            <column name="age" type="int"/>
            <column name="location" type="varchar(255)"/>
            <column name="photo_url" type="varchar(255)"/>
        </createTable>
    </changeSet>

</databaseChangeLog>
```

> ## 2. Medical Records Service
> **File: db.changelog-medical-records.xml**

```
<?xml version="1.0" encoding="UTF-8"?>

<databaseChangeLog
    xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
        http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.8.xsd">

    <changeSet id="1" author="your_username">
        <createTable tableName="medical_records">
            <column name="record_id" type="serial" autoIncrement="true">
                <constraints primaryKey="true" nullable="false"/>
            </column>
            <column name="dog_id" type="int">
                <constraints nullable="false" foreignKeyName="fk_dog_medical"
                             references="dogs(dog_id)"/>
            </column>
            <column name="description" type="text"/>
            <column name="event_date" type="date"/>
            <column name="type" type="varchar(255)"/>
        </createTable>
        <createIndex indexName="idx_dog_id" tableName="medical_records">
            <column name="dog_id"/>
        </createIndex>
    </changeSet>

</databaseChangeLog>
```

> ## 3. Donation Management Service
> **File: db.changelog-donations.xml**

```
<?xml version="1.0" encoding="UTF-8"?>

<databaseChangeLog
    xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
        http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.8.xsd">

    <changeSet id="1" author="your_username">
        <createTable tableName="donations">
            <column name="donation_id" type="serial" autoIncrement="true">
                <constraints primaryKey="true" nullable="false"/>
            </column>
            <column name="dog_id" type="int">
                <constraints nullable="false" foreignKeyName="fk_dog_donation"
                             references="dogs(dog_id)"/>
            </column>
            <column name="user_id" type="int">
                <constraints nullable="false" foreignKeyName="fk_user_donation"
                             references="users(user_id)"/>
            </column>
            <column name="amount" type="decimal(10,2)"/>
            <column name="date" type="date"/>
        </createTable>
        <createIndex indexName="idx_dog_id" tableName="donations">
            <column name="dog_id"/>
        </createIndex>
        <createIndex indexName="idx_user_id" tableName="donations">
            <column name="user_id"/>
        </createIndex>
    </changeSet>

</databaseChangeLog>
```

> **4. User Management Service**
> **File: db.changelog-users.xml**

```
<?xml version="1.0" encoding="UTF-8"?>

<databaseChangeLog
    xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
        http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.8.xsd">

    <changeSet id="1" author="your_username">
        <createTable tableName="users">
            <column name="user_id" type="serial" autoIncrement="true">
                <constraints primaryKey="true" nullable="false"/>
            </column>
            <column name="username" type="varchar(255)">
                <constraints unique="true" nullable="false"/>
            </column>
            <column name="password" type="varchar(255)" nullable="false"/>
            <column name="email" type="varchar(255)" nullable="false"/>
            <column name="role" type="varchar(255)"/>
        </createTable>
    </changeSet>

</databaseChangeLog>
```

> Each Liquibase changelog file corresponds to a specific microservice and includes the necessary DDL commands to create the respective tables. Make sure to replace "your_username" with your actual username or identifier. This structure will help you manage database versions and changes efficiently as your application evolves.

Initially, GPT created changelogs without adding indexes. When I requested it to include indexes for foreign keys, GPT promptly did so. Now I'll ask GPT to write Java classes for the table entities and include Hibernate annotations.

GPT response:

> For your pet project, I'll provide Java classes for each of the tables you've defined, including Hibernate annotations to map these classes to your database schema. These classes will represent the entities for Dogs, Medical Records, Donations, Notifications, and Users.

> **1. Dog Entity**

```
import javax.persistence.*;
import java.util.Set;

@Entity
@Table(name = "dogs")
public class Dog {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "dog_id")
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "age")
    private Integer age;

    @Column(name = "location")
    private String location;

    @Column(name = "photo_url")
    private String photoUrl;

    // Getters and Setters
}

```

> **2. Medical Record Entity**

```
import javax.persistence.*;

@Entity
@Table(name = "medical_records")
public class MedicalRecord {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "record_id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "dog_id", nullable = false)
    private Dog dog;

    @Column(name = "description")
    private String description;

    @Column(name = "event_date")
    private Date eventDate;

    @Column(name = "type")
    private String type;

    // Getters and Setters
}

```

> **3. Donation Entity**

```
import javax.persistence.*;

@Entity
@Table(name = "donations")
public class Donation {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "donation_id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "dog_id", nullable = false)
    private Dog dog;

    @ManyToOne
    @JoinColumn(name = "user_id", nullable = false)
    private User user;

    @Column(name = "amount")
    private BigDecimal amount;

    @Column(name = "date")
    private Date date;

    // Getters and Setters
}

```

> **4. Notification Entity**

```
import javax.persistence.*;

@Entity
@Table(name = "notifications")
public class Notification {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "notification_id")
    private Long id;

    @Column(name = "message")
    private String message;

    @Column(name = "date_sent")
    private Date dateSent;

    // Getters and Setters
}

```

> **5. User Entity**

```
import javax.persistence.*;
import java.util.Set;

@Entity
@Table(name = "users")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "user_id")
    private Long id;

    @Column(name = "username", unique = true)
    private String username;

    @Column(name = "password")
    private String password;

    @Column(name = "email")
    private String email;

    @Column(name = "role")
    private String role;

    // Getters and Setters
}

```

> These classes include basic entity mappings using Hibernate annotations. You may want to customize constructors, methods, and additional fields according to your specific requirements and logic, such as relations between entities (e.g., _@OneToMany_ for relations between **Dog** and **MedicalRecord** or **Donation**). Each class is annotated to correspond to the respective database table and fields, managing the primary keys, relationships, and common columns.

Great job, GPT! Can you write the controllers for me next? My next prompt was: 'Write controllers for each of my microservices.'

GPT wrote the controllers, but I forgot to ask for Swagger descriptions. So, I added another prompt: 'Could you add Swagger descriptions?' GPT did it.

I then realized that the methods in the controllers were returning entities instead of DTOs, so I asked GPT to create and return DTOs. It did, but the mapping code was inside the controllers, and some methods were returning lists of DTOs. I requested pagination to return pages and also asked for the mapping code to be extracted into separate classes. GPT managed to do that too, though it was quite challenging.

Through this process, I realized GPT isn’t as smart as I initially thought—at least not yet. I also noticed that GPT sometimes got lazy because it occasionally didn’t write the full code and instead gave responses like 'The other controllers should be written similarly,' which meant I had to ask it specifically to write the other controllers. But to be fair, it did what I asked. Next time, I should be more specific with my requirements.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/bdter2nv7lkp5bj5tgph.jpg)

GPT response:

> **1. Medical Record DTO**

```
public class MedicalRecordDTO {
    private Long id;
    private Long dogId;
    private String description;
    private Date eventDate;
    private String type;

    // Constructors, Getters and Setters
    public MedicalRecordDTO() {}

    public MedicalRecordDTO(Long id, Long dogId, String description, Date eventDate, String type) {
        this.id = id;
        this.dogId = dogId;
        this.description = description;
        this.eventDate = eventDate;
        this.type = type;
    }

    // Standard getters and setters
}

```

> **2. Donation DTO**

```
public class DonationDTO {
    private Long id;
    private Long dogId;
    private Long userId;
    private BigDecimal amount;
    private Date date;

    // Constructors, Getters and Setters
    public DonationDTO() {}

    public DonationDTO(Long id, Long dogId, Long userId, BigDecimal amount, Date date) {
        this.id = id;
        this.dogId = dogId;
        this.userId = userId;
        this.amount = amount;
        this.date = date;
    }

    // Standard getters and setters
}

```

> **3. Notification DTO**

```
public class NotificationDTO {
    private Long id;
    private String message;
    private Date dateSent;

    // Constructors, Getters and Setters
    public NotificationDTO() {}

    public NotificationDTO(Long id, String message, Date dateSent) {
        this.id = id;
        this.message = message;
        this.dateSent = dateSent;
    }

    // Standard getters and setters
}

```

> **4. User DTO**

```
public class UserDTO {
    private Long id;
    private String username;
    private String password;  // Note: Consider security implications of transmitting passwords
    private String email;
    private String role;

    // Constructors, Getters and Setters
    public UserDTO() {}

    public UserDTO(Long id, String username, String password, String email, String role) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.email = email;
        this.role = role;
    }

    // Standard getters and setters
}

```

> **Dog Management Mapper**

```
public class DogMapper {

    public static DogDTO toDogDTO(Dog dog) {
        return new DogDTO(
            dog.getId(),
            dog.getName(),
            dog.getAge(),
            dog.getLocation(),
            dog.getPhotoUrl()
        );
    }

    public static Dog toDogEntity(DogDTO dogDTO) {
        Dog dog = new Dog();
        dog.setId(dogDTO.getId());
        dog.setName(dogDTO.getName());
        dog.setAge(dogDTO.getAge());
        dog.setLocation(dogDTO.getLocation());
        dog.setPhotoUrl(dogDTO.getPhotoUrl());
        return dog;
    }
}

```

> **Medical Records Mapper**

```
public class MedicalRecordMapper {

    public static MedicalRecordDTO toMedicalRecordDTO(MedicalRecord medicalRecord) {
        return new MedicalRecordDTO(
            medicalRecord.getId(),
            medicalRecord.getDog().getId(),
            medicalRecord.getDescription(),
            medicalRecord.getEventDate(),
            medicalRecord.getType()
        );
    }

    public static MedicalRecord toMedicalRecordEntity(MedicalRecordDTO medicalRecordDTO) {
        MedicalRecord medicalRecord = new MedicalRecord();
        medicalRecord.setId(medicalRecordDTO.getId());
        Dog dog = new Dog();
        dog.setId(medicalRecordDTO.getDogId());
        medicalRecord.setDog(dog);
        medicalRecord.setDescription(medicalRecordDTO.getDescription());
        medicalRecord.setEventDate(medicalRecordDTO.getEventDate());
        medicalRecord.setType(medicalRecordDTO.getType());
        return medicalRecord;
    }
}

```

> **Donation Mapper**

```
public class DonationMapper {

    public static DonationDTO toDonationDTO(Donation donation) {
        return new DonationDTO(
            donation.getId(),
            donation.getDog().getId(),
            donation.getUser().getId(),
            donation.getAmount(),
            donation.getDate()
        );
    }

    public static Donation toDonationEntity(DonationDTO donationDTO) {
        Donation donation = new Donation();
        donation.setId(donationDTO.getId());
        Dog dog = new Dog();
        dog.setId(donationDTO.getDogId());
        User user = new User();
        user.setId(donationDTO.getUserId());
        donation.setDog(dog);
        donation.setUser(user);
        donation.setAmount(donationDTO.getAmount());
        donation.setDate(donationDTO.getDate());
        return donation;
    }
}

```

> **Notification Mapper**

```
public class NotificationMapper {

    public static NotificationDTO toNotificationDTO(Notification notification) {
        return new NotificationDTO(
            notification.getId(),
            notification.getMessage(),
            notification.getDateSent()
        );
    }

    public static Notification toNotificationEntity(NotificationDTO notificationDTO) {
        Notification notification = new Notification();
        notification.setId(notificationDTO.getId());
        notification.setMessage(notificationDTO.getMessage());
        notification.setDateSent(notificationDTO.getDateSent());
        return notification;
    }
}

```

> **User Mapper**

```
public class UserMapper {

    public static UserDTO toUserDTO(User user) {
        return new UserDTO(
            user.getId(),
            user.getUsername(),
            user.getPassword(),
            user.getEmail(),
            user.getRole()
        );
    }

    public static User toUserEntity(UserDTO userDTO) {
        User user = new User();
        user.setId(userDTO.getId());
        user.setUsername(userDTO.getUsername());
        user.setPassword(userDTO.getPassword());  // Make sure to hash the password in the service layer
        user.setEmail(userDTO.getEmail());
        user.setRole(userDTO.getRole());
        return user;
    }
}
```

> **Medical Records Controller with MedicalRecordMapper**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/medical-records")
@Api(value = "Medical Record Management", description = "Operations pertaining to medical records of dogs in the application")
public class MedicalRecordController {

    @Autowired
    private MedicalRecordService medicalRecordService;

    @ApiOperation(value = "Add a new medical record for a dog", response = MedicalRecordDTO.class)
    @PostMapping
    public ResponseEntity<MedicalRecordDTO> addMedicalRecord(@RequestBody MedicalRecordDTO medicalRecordDTO) {
        MedicalRecord medicalRecord = MedicalRecordMapper.toMedicalRecordEntity(medicalRecordDTO);
        MedicalRecord createdMedicalRecord = medicalRecordService.addMedicalRecord(medicalRecord);
        return ResponseEntity.ok(MedicalRecordMapper.toMedicalRecordDTO(createdMedicalRecord));
    }

    @ApiOperation(value = "Retrieve medical records by dog ID with pagination", response = MedicalRecordDTO.class, responseContainer = "List")
    @GetMapping("/{dogId}")
    public ResponseEntity<Page<MedicalRecordDTO>> getMedicalRecordsByDogId(
        @PathVariable Long dogId,
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "10") int size) {
        Page<MedicalRecord> records = medicalRecordService.getMedicalRecordsByDogId(dogId, PageRequest.of(page, size));
        Page<MedicalRecordDTO> recordDTOs = records.map(MedicalRecordMapper::toMedicalRecordDTO);
        return ResponseEntity.ok(recordDTOs);
    }

    @ApiOperation(value = "Update an existing medical record", response = MedicalRecordDTO.class)
    @PutMapping("/{id}")
    public ResponseEntity<MedicalRecordDTO> updateMedicalRecord(@PathVariable Long id, @RequestBody MedicalRecordDTO medicalRecordDTO) {
        MedicalRecord medicalRecord = MedicalRecordMapper.toMedicalRecordEntity(medicalRecordDTO);
        medicalRecord.setId(id);
        MedicalRecord updatedMedicalRecord = medicalRecordService.updateMedicalRecord(medicalRecord);
        return ResponseEntity.ok(MedicalRecordMapper.toMedicalRecordDTO(updatedMedicalRecord));
    }

    @ApiOperation(value = "Delete a medical record")
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteMedicalRecord(@PathVariable Long id) {
        medicalRecordService.deleteMedicalRecord(id);
        return ResponseEntity.ok().build();
    }
}
```

> **Donation Management Controller with DonationMapper**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/donations")
@Api(value = "Donation Management", description = "Operations pertaining to donations made to dogs")
public class DonationController {

    @Autowired
    private DonationService donationService;

    @ApiOperation(value = "Make a donation", response = DonationDTO.class)
    @PostMapping
    public ResponseEntity<DonationDTO> makeDonation(@RequestBody DonationDTO donationDTO) {
        Donation donation = DonationMapper.toDonationEntity(donationDTO);
        Donation createdDonation = donationService.makeDonation(donation);
        return ResponseEntity.ok(DonationMapper.toDonationDTO(createdDonation));
    }

    @ApiOperation(value = "Get all donations made for a specific dog with pagination", response = DonationDTO.class, responseContainer = "List")
    @GetMapping("/{dogId}")
    public ResponseEntity<Page<DonationDTO>> getDonationsByDogId(
        @PathVariable Long dogId,
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "10") int size) {
        Page<Donation> donations = donationService.getDonationsByDogId(dogId, PageRequest.of(page, size));
        Page<DonationDTO> donationDTOs = donations.map(DonationMapper::toDonationDTO);
        return ResponseEntity.ok(donationDTOs);
    }
}
```

> **Notification Management Controller with NotificationMapper**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/notifications")
@Api(value = "Notification Management", description = "Management of notifications sent to users")
public class NotificationController {

    @Autowired
    private NotificationService notificationService;

    @ApiOperation(value = "Send a notification", response = NotificationDTO.class)
    @PostMapping
    public ResponseEntity<NotificationDTO> sendNotification(@RequestBody NotificationDTO notificationDTO) {
        Notification notification = NotificationMapper.toNotificationEntity(notificationDTO);
        Notification sentNotification = notificationService.sendNotification(notification);
        return ResponseEntity.ok(NotificationMapper.toNotificationDTO(sentNotification));
    }

    @ApiOperation(value = "List all notifications with pagination", response = NotificationDTO.class, responseContainer = "List")
    @GetMapping
    public ResponseEntity<Page<NotificationDTO>> getAllNotifications(
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "10") int size) {
        Page<Notification> notifications = notificationService.getAllNotifications(PageRequest.of(page, size));
        Page<NotificationDTO> notificationDTOs = notifications.map(NotificationMapper::toNotificationDTO);
        return ResponseEntity.ok(notificationDTOs);
    }
}

```

> **User Management Controller with UserMapper**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/users")
@Api(value = "User Management", description = "Operations pertaining to users in the application")
public class UserController {

    @Autowired
    private UserService userService;

    @ApiOperation(value = "Register a new user", response = UserDTO.class)
    @PostMapping
    public ResponseEntity<UserDTO> registerUser(@RequestBody UserDTO userDTO) {
        User user = UserMapper.toUserEntity(userDTO);
        User registeredUser = userService.registerUser(user);
        return ResponseEntity.ok(UserMapper.toUserDTO(registeredUser));
    }

    @ApiOperation(value = "Get a user by ID", response = UserDTO.class)
    @GetMapping("/{id}")
    public ResponseEntity<UserDTO> getUserById(@PathVariable Long id) {
        User user = userService.getUserById(id);
        return ResponseEntity.ok(UserMapper.toUserDTO(user));
    }

    @ApiOperation(value = "Update an existing user", response = UserDTO.class)
    @PutMapping("/{id}")
    public ResponseEntity<UserDTO> updateUser(@PathVariable Long id, @RequestBody UserDTO userDTO) {
        User user = UserMapper.toUserEntity(userDTO);
        user.setId(id);
        User updatedUser = userService.updateUser(user);
        return ResponseEntity.ok(UserMapper.toUserDTO(updatedUser));
    }

    @ApiOperation(value = "Delete a user")
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
        userService.deleteUser(id);
        return ResponseEntity.ok().build();
    }

    @ApiOperation(value = "List all users with pagination", response = UserDTO.class, responseContainer = "List")
    @GetMapping
    public ResponseEntity<Page<UserDTO>> getAllUsers(
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "10") int size) {
        Page<User> users = userService.getAllUsers(PageRequest.of(page, size));
        Page<UserDTO> userDTOs = users.map(UserMapper::toUserDTO);
        return ResponseEntity.ok(userDTOs);
    }
}

```

Then I wrote, 'Create services and repositories for each microservice.'

GPT response:

> ## Dog Management Service and Repository
> **DogRepository.java**

```
import org.springframework.data.jpa.repository.JpaRepository;

public interface DogRepository extends JpaRepository<Dog, Long> {
}

```

> **DogService.java**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.Optional;

@Service
public class DogService {

    @Autowired
    private DogRepository dogRepository;

    public Dog createDog(Dog dog) {
        return dogRepository.save(dog);
    }

    public Dog updateDog(Dog dog) {
        return dogRepository.save(dog);
    }

    public Dog getDogById(Long id) {
        return dogRepository.findById(id).orElseThrow(() -> new RuntimeException("Dog not found"));
    }

    public void deleteDog(Long id) {
        dogRepository.deleteById(id);
    }

    public Page<Dog> getAllDogs(Pageable pageable) {
        return dogRepository.findAll(pageable);
    }
}

```

> ## Medical Records Service and Repository
> **MedicalRecordRepository.java**

```
import org.springframework.data.jpa.repository.JpaRepository;

public interface MedicalRecordRepository extends JpaRepository<MedicalRecord, Long> {
    Page<MedicalRecord> findByDogId(Long dogId, Pageable pageable);
}

```

> **MedicalRecordService.java**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MedicalRecordService {

    @Autowired
    private MedicalRecordRepository medicalRecordRepository;

    public MedicalRecord addMedicalRecord(MedicalRecord medicalRecord) {
        return medicalRecordRepository.save(medicalRecord);
    }

    public MedicalRecord updateMedicalRecord(MedicalRecord medicalRecord) {
        return medicalRecordRepository.save(medicalRecord);
    }

    public void deleteMedicalRecord(Long id) {
        medicalRecordRepository.deleteById(id);
    }

    public Page<MedicalRecord> getMedicalRecordsByDogId(Long dogId, Pageable pageable) {
        return medicalRecordRepository.findByDogId(dogId, pageable);
    }
}

```

> ## Donation Management Service and Repository
> **DonationRepository.java**

```
import org.springframework.data.jpa.repository.JpaRepository;

public interface DonationRepository extends JpaRepository<Donation, Long> {
    Page<Donation> findByDogId(Long dogId, Pageable pageable);
}

```

> **DonationService.java**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class DonationService {

    @Autowired
    private DonationRepository donationRepository;

    public Donation makeDonation(Donation donation) {
        return donationRepository.save(donation);
    }

    public Page<Donation> getDonationsByDogId(Long dogId, Pageable pageable) {
        return donationRepository.findByDogId(dogId, pageable);
    }
}

```

> ## Notification Management Service and Repository
> **NotificationRepository.java**

```
import org.springframework.data.jpa.repository.JpaRepository;

public interface NotificationRepository extends JpaRepository<Notification, Long> {
}

```

> **NotificationService.java**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class NotificationService {

    @Autowired
    private NotificationRepository notificationRepository;

    public Notification sendNotification(Notification notification) {
        return notificationRepository.save(notification);
    }

    public Page<Notification> getAllNotifications(Pageable pageable) {
        return notificationRepository.findAll(pageable);
    }
}

```

> ## User Management Service and Repository
> **UserRepository.java**

```
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
}

```

> **UserService.java**

```
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    public User registerUser(User user) {
        return userRepository.save(user);
    }

    public User updateUser(User user) {
        return userRepository.save(user);
    }

    public void deleteUser(Long id) {
        userRepository.deleteById(id);
    }

    public User getUserById(Long id) {
        return userRepository.findById(id).orElseThrow(() -> new RuntimeException("User not found"));
    }

    public Page<User> getAllUsers(Pageable pageable) {
        return userRepository.findAll(pageable);
    }
}

```

> These services and repositories are designed to provide a clean, functional interface for each part of your application, facilitating data management and business logic execution. They are crafted using Spring Data JPA's JpaRepository, which offers a broad range of methods for CRUD operations and paging.

At this point, I wanted to write the conclusion, but I realized we haven't created the Search Service yet. So, my next prompt is, 'What about the search service? We haven't done anything for it.'

GPT response: 

> Creating a search service, especially for an application like yours that handles entities such as dogs, medical records, donations, etc., can greatly enhance user experience by allowing quick and efficient retrieval of data based on various criteria. For implementing a search service, we will typically consider integrating a technology optimized for search operations, such as Elasticsearch, which you mentioned earlier, or a simpler implementation using database queries if the scale and complexity are limited.
> Let's outline how you could set up a basic search service using database queries and later discuss how it could be extended to use Elasticsearch.

> ## Basic Search Service Using Spring Data JPA Specifications

> You can use Spring Data JPA Specifications to build a dynamic query for searching dogs based on attributes like name, age, and location. This approach leverages the _JpaSpecificationExecutor_ interface provided by Spring Data.

> **Dog Specification for Search**

> First, let's create a _Specification_ class that will be used to construct the queries based on the search criteria.

```
import org.springframework.data.jpa.domain.Specification;
import javax.persistence.criteria.*;

public class DogSpecification {

    public static Specification<Dog> hasName(String name) {
        return (root, query, criteriaBuilder) -> {
            if (name == null) return criteriaBuilder.isTrue(criteriaBuilder.literal(true)); // always true
            return criteriaBuilder.like(criteriaBuilder.lower(root.get("name")), "%" + name.toLowerCase() + "%");
        };
    }

    public static Specification<Dog> hasAge(Integer age) {
        return (root, query, criteriaBuilder) -> {
            if (age == null) return criteriaBuilder.isTrue(criteriaBuilder.literal(true));
            return criteriaBuilder.equal(root.get("age"), age);
        };
    }

    public static Specification<Dog> hasLocation(String location) {
        return (root, query, criteriaBuilder) -> {
            if (location == null) return criteriaBuilder.isTrue(criteriaBuilder.literal(true));
            return criteriaBuilder.like(criteriaBuilder.lower(root.get("location")), "%" + location.toLowerCase() + "%");
        };
    }

    public static Specification<Dog> buildSearchSpec(String name, Integer age, String location) {
        return Specification.where(hasName(name)).and(hasAge(age)).and(hasLocation(location));
    }
}

```

> **DogRepository Update**

> Extend _DogRepository_ to include _JpaSpecificationExecutor_:

```
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface DogRepository extends JpaRepository<Dog, Long>, JpaSpecificationExecutor<Dog> {
}

```

> ## Search Service Implementation

> Now, implement the search logic in the _DogService_.

```
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;

@Service
public class DogSearchService {

    @Autowired
    private DogRepository dogRepository;

    public Page<DogDTO> searchDogs(String name, Integer age, String location, Pageable pageable) {
        Specification<Dog> spec = DogSpecification.buildSearchSpec(name, age, location);
        Page<Dog> dogs = dogRepository.findAll(spec, pageable);
        return dogs.map(DogMapper::toDogDTO);
    }
}

```

> ## Extending to Use Elasticsearch

> If your application requires more complex search functionalities like full-text search, scalability across a large dataset, or faster response times, integrating Elasticsearch would be beneficial.

> - **1 Elasticsearch Repository:** Use Spring Data Elasticsearch to define a repository for _Dog_.
> - **2 Indexing Service:** Implement a service to handle the indexing of dog entities into Elasticsearch.
> - **3 Search Method:** Create methods in the _DogSearchService_ to utilize Elasticsearch's capabilities, such as full-text search, filtering, and sorting.

> Here's a brief concept for integrating Elasticsearch:

```
import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;

public interface DogSearchRepository extends ElasticsearchRepository<Dog, Long> {
    Page<Dog> findByDescriptionContaining(String description, Pageable pageable);
}

```

> This setup would require additional configuration for Elasticsearch and potentially a synchronization mechanism between your primary database and the Elasticsearch index.

> Using these approaches, you can tailor the complexity and performance of the search functionality to meet the specific demands and scale of your application.

**Conclusion** 

GPT is a fascinating tool. It can create a plan for a pet project and write applications based on specific requirements. However, the requirements need to be very clear. GPT will do exactly what I ask without questioning it, even if my request is misguided. This is the biggest difference compared to a human mentor. If my requests are not well-formulated, GPT will write code that no highly qualified developer would find acceptable.

Now it's time to build the projects and move on to learning and applying the next technologies according to the plan.