MongoDB

<?xml version="1.0" encoding="UTF-8"?>
        <project xmlns="http://maven.apache.org/POM/4.0.0"
                 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
            <modelVersion>4.0.0</modelVersion>
            <parent>
                <groupId>at.aydin.academy</groupId>
                <artifactId>24mongodb-pair</artifactId>
                <version>1.0.0</version>
                <relativePath>../pom.xml</relativePath>
            </parent>
            <artifactId>mongodb-driver-legacy</artifactId>
            <packaging>jar</packaging>
            <name>MongoDB Driver Legacy</name>

            <dependencies>
                <dependency><groupId>org.mongodb</groupId><artifactId>mongodb-driver-sync</artifactId></dependency>
<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
</dependency>

            </dependencies>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-compiler-plugin</artifactId>
                    </plugin>

                </plugins>
            </build>
        </project>

package at.aydin.lab.mongodb.legacy;

public record LegacyBook(String id, String title, int year) {
}

package at.aydin.lab.mongodb.legacy;

import org.bson.Document;

// Design Pattern: Data Mapper
// Zweck: Übersetzt manuell zwischen Fachobjekt und MongoDB Document.
public final class LegacyBookMapper {
    public Document toDocument(LegacyBook b) {
        return new Document("_id", b.id()).append("title", b.title()).append("year", b.year());
    }

    public LegacyBook fromDocument(Document d) {
        return new LegacyBook(d.getString("_id"), d.getString("title"), d.getInteger("year"));
    }
}

package at.aydin.lab.mongodb.legacy;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

class LegacyBookMapperTest {
    @Test
    void mapsDocument() {
        var m = new LegacyBookMapper();
        var b = new LegacyBook("1", "Java", 2026);
        assertEquals(b, m.fromDocument(m.toDocument(b)));
    }
}

package at.aydin.lab.mongodb.legacy;

import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.ReplaceOptions;
import org.bson.Document;
import java.util.ArrayList;
import java.util.List;
import static com.mongodb.client.model.Filters.gte;

// Design Pattern: Repository
// Zweck: Mongo-Driver, BSON-Filter und manuelles Mapping werden hinter einer fachlichen API gekapselt.
public final class LegacyBookRepository {
    private final MongoCollection<Document> collection;
    private final LegacyBookMapper mapper;
    public LegacyBookRepository(MongoCollection<Document> collection, LegacyBookMapper mapper) {
        this.collection = collection;
        this.mapper = mapper;
    }

    public void save(LegacyBook book) {
        collection.replaceOne(new Document("_id", book.id()), mapper.toDocument(book), new ReplaceOptions().upsert(true));
    }

    public List<LegacyBook> findByYearGreaterThanEqual(int year) {
        List<LegacyBook> result = new ArrayList<>();
        for (Document document : collection.find(gte("year", year))) {
            result.add(mapper.fromDocument(document));
        }
        return List.copyOf(result);
    }
}