### Spring Boot Offset Pagination Repository Calls

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/HibernateSpringBootOffsetPagination/README.md

Examples of calling the built-in `findAll(Pageable)` method with and without sorting, and using Spring Data query creation for custom methods.

```java
repository.findAll(PageRequest.of(page, size));
```

```java
repository.findAll(PageRequest.of(page, size, new Sort(Sort.Direction.ASC, "name")));
```

```java
Page<Author> findByName(String name, Pageable pageable);
```

```java
Page<Author> queryFirst10ByName(String name, Pageable pageable);
```

--------------------------------

### Fetch Player Data with JavaScript

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/SpringBootPayaraMySqlKickoffApplication/src/main/webapp/index.html

Use this function to send a GET request to retrieve player data. The server endpoint '/players/fetch' should be set up to handle player retrieval.

```javascript
function fetchPlayer() { var xhttp = new XMLHttpRequest(); xhttp.onreadystatechange = function () { if (this.readyState === 4 && this.status === 200) { alert(this.responseText); } }; xhttp.open("GET", "/players/fetch", true); xhttp.setRequestHeader("Content-type", "application/json; charset=utf-8"); xhttp.send(); }
```

--------------------------------

### Batch Inserts using saveAll in Spring Boot JPA

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/README.md

This example demonstrates how to perform batch inserts efficiently using the `saveAll(Iterable<S> entities)` method provided by `SimpleJpaRepository` in a Spring Boot application with MySQL.

```java
List<User> users = new ArrayList<>();
for (int i = 0; i < 10000; i++) {
    users.add(new User("User " + i));
}

userRepository.saveAll(users);
```

--------------------------------

### Setup Spring Data JPA Auditing

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/README.md

Implement auditing to maintain history records and track user activities. Requires an abstract base entity with auditing annotations and an AuditorAware implementation.

```java
abstract class BaseEntity<U> {

    @CreatedDate
    @Column(nullable = false)
    @JsonIgnore
    protected LocalDateTime created;

    @LastModifiedDate
    @Column(nullable = false)
    @JsonIgnore
    protected LocalDateTime lastModified;

    @CreatedBy
    @Column(updatable = false)
    @JsonIgnore
    protected U createdBy;

    @LastModifiedBy
    @Column(nullable = false)
    @JsonIgnore
    protected U lastModifiedBy;

}

@Configuration
@EnableJpaAuditing(auditorAwareRef = "auditorProvider")
class AuditingConfig {

    @Bean
    public AuditorProvider auditorProvider(SpringSecurityAuditorAware auditorAware) {
        return auditorProvider;
    }

}

@Component
class SpringSecurityAuditorAware implements AuditorAware<U> {

    @Override
    public Optional<U> getCurrentAuditor() {
        // Use Spring Security to return the currently logged-in user
        // Example: return Optional.of(SecurityContextHolder.getContext().getAuthentication().getName());
        return null; // Placeholder
    }

}

@MappedSuperclass
@EntityListeners({AuditingEntityListener.class})
abstract class BaseEntity<U> {

    @CreatedDate
    @Column(nullable = false)
    @JsonIgnore
    protected LocalDateTime created;

    @LastModifiedDate
    @Column(nullable = false)
    @JsonIgnore
    protected LocalDateTime lastModified;

    @CreatedBy
    @Column(updatable = false)
    @JsonIgnore
    protected U createdBy;

    @LastModifiedBy
    @Column(nullable = false)
    @JsonIgnore
    protected U lastModifiedBy;

}

@Configuration
@EnableJpaAuditing(auditorAwareRef = "auditorProvider")
class AuditingConfig {

    @Bean
    public AuditorProvider auditorProvider(SpringSecurityAuditorAware auditorAware) {
        return auditorProvider;
    }

}

@Component
class SpringSecurityAuditorAware implements AuditorAware<U> {

    @Override
    public Optional<U> getCurrentAuditor() {
        // Use Spring Security to return the currently logged-in user
        // Example: return Optional.of(SecurityContextHolder.getContext().getAuthentication().getName());
        return null; // Placeholder
    }

}
```

--------------------------------

### Hibernate Envers Auditing Setup

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/README.md

Configure Hibernate Envers for auditing by annotating entities with `@Audited`. Optionally, rename audit tables using `@AuditTable`.

```java
@Audited
@Entity
class Book {
    // ...
}

@AuditTable("book_audits")
@Audited
@Entity
class BookAudit {
    // ...
}
```

--------------------------------

### Build Project and Docker Image

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/Java EE/CMPCandCMT/README.md

Use Maven to clean and package the project, then build a Docker image for the application.

```bash
mvn clean package && docker build -t com.sample/quickstart .
```

--------------------------------

### Create New Player with JavaScript

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/SpringBootPayaraMySqlKickoffApplication/src/main/webapp/index.html

Use this function to send a POST request to create a new player. Ensure the server endpoint '/players/new' is correctly configured.

```javascript
function newPlayer() { var xhttp = new XMLHttpRequest(); xhttp.onreadystatechange = function () { if (this.readyState === 4 && this.status === 200) { alert(this.responseText); } }; xhttp.open("POST", "/players/new", true); xhttp.setRequestHeader("Content-type", "application/json; charset=utf-8"); xhttp.send(); }
```

--------------------------------

### Author Specification Example

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/HibernateSpringBootSliceAllCriteriaBuilderSortAndSpecificationAndQueryHints/README.md

Defines a Spring Data `Specification` to filter `Author` entities by age greater than 45. This can be used with repository methods that accept `Specification`.

```java
public static Specification<Author> isAgeGt45() {
    // ...
}
```

--------------------------------

### Fetch Slice with Specification, Sort, and Query Hints

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/HibernateSpringBootSliceAllCriteriaBuilderSortAndSpecificationAndQueryHints/README.md

Demonstrates fetching a `Slice<Author>` using a `Specification`, `PageRequest` with custom `Sort`, and passing query hints. This method avoids the `SELECT COUNT` query.

```java
public Slice<Author> fetchNextSlice(int page, int size) {
    // hint example
    Map<String, Object> hints = new HashMap<>();
    hints.put("...", value);
        
    return authorRepository.findAll(isAgeGt45(),
        PageRequest.of(page, size, new Sort(Sort.Direction.ASC, "age")),
        LockModeType..., hints);
}
```

--------------------------------

### Fetch Next Page with Keyset Pagination

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/README.md

Implement keyset pagination to efficiently determine if more records exist for a 'Next Page' button. This method fetches one extra record to check for the next page's existence.

```java
public AuthorView fetchNextPage(long id, int limit) {
    List<Author> authors = authorRepository.fetchAll(id, limit + 1);

    if (authors.size() == (limit + 1)) {
        authors.remove(authors.size() - 1);
        return new AuthorView(authors, true);
    }

    return new AuthorView(authors, false);
}
```

```java
public Map<List<Author>, Boolean> fetchNextPage(long id, int limit) {
    List<Author> authors = authorRepository.fetchAll(id, limit + 1);
        
    if(authors.size() == (limit + 1)) {
        authors.remove(authors.size() -1);
        return Collections.singletonMap(authors, true);
    }
        
    return Collections.singletonMap(authors, false);
}
```

--------------------------------

### Generate Two MySQL Databases and Match Entities

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/README.md

Set up two distinct MySQL databases and map entities to their respective tables using the `@Table` annotation with a schema attribute. The JDBC URL should not include a specific database name.

```properties
spring.datasource.url=jdbc:mysql://localhost:3306
```

--------------------------------

### Fetch Next Slice with Sorting

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/HibernateSpringBootSliceAllCriteriaBuilderAndSort/README.md

This method demonstrates how to fetch the next slice of data with sorting applied. It uses `PageRequest.of` to specify the page number, size, and sort order.

```Java
public Slice<Author> fetchNextSlice(int page, int size) {
    return authorRepository.findAll(PageRequest.of(page, size, new Sort(Sort.Direction.ASC, "age")));
}
```

--------------------------------

### Run Docker Container

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/Java EE/CMPCandCMT/README.md

Remove any existing container with the same name and then run the Docker image as a detached container, exposing ports 8080 and 4848.

```bash
docker rm -f quickstart || true && docker run -d -p 8080:8080 -p 4848:4848 --name quickstart com.sample/quickstart
```

--------------------------------

### Enable Log4j 2 Trace for Hibernate SQL Statements

Source: https://github.com/anghelleonard/hibernate-springboot/blob/master/README.md

Configure Log4j 2 to view prepared statement binding and extracted parameters. This requires excluding Spring Boot's default logging and adding the Log4j 2 dependency.

```xml
<Logger name="org.hibernate.type.descriptor.sql" level="trace"/>
```