Add BAEL-2272 persisting DDD aggregates examples (#5630)

* Add BAEL-2272 persisting DDD aggregates examples

* Update pom.xml

ddd/pom.xml

@@ -0,0 +1,91 @@
+<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.0.6.RELEASE</version>
+        <relativePath /> <!-- lookup parent from repository -->
+    </parent>
+
+    <groupId>com.baeldung.ddd</groupId>
+    <artifactId>ddd</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>ddd</name>
+    <description>DDD series examples</description>
+
+    <properties>
+        <joda-money.version>1.0.1</joda-money.version>
+        <maven-surefire-plugin.version>2.22.0</maven-surefire-plugin.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-mongodb</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <!-- JUnit platform launcher -->
+        <!-- To be able to run tests from IDE directly -->
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-launcher</artifactId>
+            <version>${junit-platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.joda</groupId>
+            <artifactId>joda-money</artifactId>
+            <version>${joda-money.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-devtools</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>de.flapdoodle.embed</groupId>
+            <artifactId>de.flapdoodle.embed.mongo</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

ddd/src/main/java/com/baeldung/ddd/PersistingDddAggregatesApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.ddd;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class PersistingDddAggregatesApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(PersistingDddAggregatesApplication.class, args);
+	}
+}

ddd/src/main/java/com/baeldung/ddd/order/Order.java

@@ -0,0 +1,52 @@
+package com.baeldung.ddd.order;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.joda.money.Money;
+
+public class Order {
+    private final List<OrderLine> orderLines;
+    private Money totalCost;
+
+    public Order(List<OrderLine> orderLines) {
+        checkNotNull(orderLines);
+        if (orderLines.isEmpty()) {
+            throw new IllegalArgumentException("Order must have at least one order line item");
+        }
+        this.orderLines = new ArrayList<>(orderLines);
+        totalCost = calculateTotalCost();
+    }
+
+    public void addLineItem(OrderLine orderLine) {
+        checkNotNull(orderLine);
+        orderLines.add(orderLine);
+        totalCost = totalCost.plus(orderLine.cost());
+    }
+
+    public List<OrderLine> getOrderLines() {
+        return new ArrayList<>(orderLines);
+    }
+
+    public void removeLineItem(int line) {
+        OrderLine removedLine = orderLines.remove(line);
+        totalCost = totalCost.minus(removedLine.cost());
+    }
+
+    public Money totalCost() {
+        return totalCost;
+    }
+
+    private Money calculateTotalCost() {
+        return orderLines.stream()
+            .map(OrderLine::cost)
+            .reduce(Money::plus)
+            .get();
+    }
+
+    private static void checkNotNull(Object par) {
+        if (par == null) {
+            throw new NullPointerException("Parameter cannot be null");
+        }
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/OrderLine.java

@@ -0,0 +1,67 @@
+package com.baeldung.ddd.order;
+
+import org.joda.money.Money;
+
+public class OrderLine {
+    private final Product product;
+    private final int quantity;
+
+    public OrderLine(Product product, int quantity) {
+        super();
+        this.product = product;
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        OrderLine other = (OrderLine) obj;
+        if (product == null) {
+            if (other.product != null) {
+                return false;
+            }
+        } else if (!product.equals(other.product)) {
+            return false;
+        }
+        if (quantity != other.quantity) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((product == null) ? 0 : product.hashCode());
+        result = prime * result + quantity;
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "OrderLine [product=" + product + ", quantity=" + quantity + "]";
+    }
+
+    Money cost() {
+        return product.getPrice()
+            .multipliedBy(quantity);
+    }
+
+    Product getProduct() {
+        return product;
+    }
+
+    int getQuantity() {
+        return quantity;
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/Product.java

@@ -0,0 +1,52 @@
+package com.baeldung.ddd.order;
+
+import org.joda.money.Money;
+
+public class Product {
+    private final Money price;
+
+    public Product(Money price) {
+        super();
+        this.price = price;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        Product other = (Product) obj;
+        if (price == null) {
+            if (other.price != null) {
+                return false;
+            }
+        } else if (!price.equals(other.price)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((price == null) ? 0 : price.hashCode());
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "Product [price=" + price + "]";
+    }
+
+    Money getPrice() {
+        return price;
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrder.java

@@ -0,0 +1,111 @@
+package com.baeldung.ddd.order.jpa;
+
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.ElementCollection;
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "order_table")
+class JpaOrder {
+    private String currencyUnit;
+    @Id
+    @GeneratedValue
+    private Long id;
+    @ElementCollection(fetch = FetchType.EAGER)
+    private final List<JpaOrderLine> orderLines;
+    private BigDecimal totalCost;
+
+    JpaOrder() {
+        totalCost = null;
+        orderLines = new ArrayList<>();
+    }
+
+    JpaOrder(List<JpaOrderLine> orderLines) {
+        checkNotNull(orderLines);
+        if (orderLines.isEmpty()) {
+            throw new IllegalArgumentException("Order must have at least one order line item");
+        }
+        this.orderLines = new ArrayList<>(orderLines);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaOrder other = (JpaOrder) obj;
+        if (id == null) {
+            if (other.id != null) {
+                return false;
+            }
+        } else if (!id.equals(other.id)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaOrder [currencyUnit=" + currencyUnit + ", id=" + id + ", orderLines=" + orderLines + ", totalCost=" + totalCost + "]";
+    }
+
+    void addLineItem(JpaOrderLine orderLine) {
+        checkNotNull(orderLine);
+        orderLines.add(orderLine);
+    }
+
+    String getCurrencyUnit() {
+        return currencyUnit;
+    }
+
+    Long getId() {
+        return id;
+    }
+
+    List<JpaOrderLine> getOrderLines() {
+        return new ArrayList<>(orderLines);
+    }
+
+    BigDecimal getTotalCost() {
+        return totalCost;
+    }
+
+    void removeLineItem(int line) {
+        JpaOrderLine removedLine = orderLines.remove(line);
+    }
+
+    void setCurrencyUnit(String currencyUnit) {
+        this.currencyUnit = currencyUnit;
+    }
+
+    void setTotalCost(BigDecimal totalCost) {
+        this.totalCost = totalCost;
+    }
+
+    private static void checkNotNull(Object par) {
+        if (par == null) {
+            throw new NullPointerException("Parameter cannot be null");
+        }
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrderLine.java

@@ -0,0 +1,70 @@
+package com.baeldung.ddd.order.jpa;
+
+import javax.persistence.Embeddable;
+import javax.persistence.Embedded;
+
+@Embeddable
+class JpaOrderLine {
+    @Embedded
+    private final JpaProduct product;
+    private final int quantity;
+
+    JpaOrderLine() {
+        quantity = 0;
+        product = null;
+    }
+
+    JpaOrderLine(JpaProduct product, int quantity) {
+        super();
+        this.product = product;
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaOrderLine other = (JpaOrderLine) obj;
+        if (product == null) {
+            if (other.product != null) {
+                return false;
+            }
+        } else if (!product.equals(other.product)) {
+            return false;
+        }
+        if (quantity != other.quantity) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((product == null) ? 0 : product.hashCode());
+        result = prime * result + quantity;
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaOrderLine [product=" + product + ", quantity=" + quantity + "]";
+    }
+
+    JpaProduct getProduct() {
+        return product;
+    }
+
+    int getQuantity() {
+        return quantity;
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrderRepository.java

@@ -0,0 +1,7 @@
+package com.baeldung.ddd.order.jpa;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface JpaOrderRepository extends JpaRepository<JpaOrder, Long> {
+
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaProduct.java

@@ -0,0 +1,79 @@
+package com.baeldung.ddd.order.jpa;
+
+import java.math.BigDecimal;
+
+import javax.persistence.Embeddable;
+
+@Embeddable
+class JpaProduct {
+    private String currencyUnit;
+    private BigDecimal price;
+
+    public JpaProduct() {
+    }
+
+    public JpaProduct(BigDecimal price, String currencyUnit) {
+        super();
+        this.price = price;
+        currencyUnit = currencyUnit;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaProduct other = (JpaProduct) obj;
+        if (currencyUnit == null) {
+            if (other.currencyUnit != null) {
+                return false;
+            }
+        } else if (!currencyUnit.equals(other.currencyUnit)) {
+            return false;
+        }
+        if (price == null) {
+            if (other.price != null) {
+                return false;
+            }
+        } else if (!price.equals(other.price)) {
+            return false;
+        }
+        return true;
+    }
+
+    public String getCurrencyUnit() {
+        return currencyUnit;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((currencyUnit == null) ? 0 : currencyUnit.hashCode());
+        result = prime * result + ((price == null) ? 0 : price.hashCode());
+        return result;
+    }
+
+    public void setCurrencyUnit(String currencyUnit) {
+        this.currencyUnit = currencyUnit;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaProduct [currencyUnit=" + currencyUnit + ", price=" + price + "]";
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/mongo/OrderMongoRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.ddd.order.mongo;
+
+import org.springframework.data.mongodb.repository.MongoRepository;
+
+import com.baeldung.ddd.order.Order;
+
+public interface OrderMongoRepository extends MongoRepository<Order, String> {
+
+}

ddd/src/test/java/com/baeldung/ddd/order/OrderTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.ddd.order;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.catchThrowable;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+class OrderTest {
+    @DisplayName("given order with two items, when calculate total cost, then sum is returned")
+    @Test
+    void test0() throws Exception {
+        // given
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 2);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 5.00)), 10);
+        Order order = new Order(Arrays.asList(ol0, ol1));
+
+        // when
+        Money totalCost = order.totalCost();
+
+        // then
+        assertThat(totalCost).isEqualTo(Money.of(CurrencyUnit.USD, 70.00));
+    }
+
+    @DisplayName("when create order without line items, then exception is thrown")
+    @Test
+    void test1() throws Exception {
+        // when
+        Throwable throwable = catchThrowable(() -> new Order(new ArrayList<>()));
+
+        // then
+        assertThat(throwable).isInstanceOf(IllegalArgumentException.class);
+    }
+
+    @DisplayName("given order with two line items, when add another line item, then total cost is updated")
+    @Test
+    void test2() throws Exception {
+        // given
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 1);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 5.00)), 1);
+        Order order = new Order(Arrays.asList(ol0, ol1));
+
+        // when
+        order.addLineItem(new OrderLine(new Product(Money.of(CurrencyUnit.USD, 20.00)), 2));
+
+        // then
+        assertThat(order.totalCost()).isEqualTo(Money.of(CurrencyUnit.USD, 55));
+    }
+
+    @DisplayName("given order with three line items, when remove item, then total cost is updated")
+    @Test
+    void test3() throws Exception {
+        // given
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 1);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 20.00)), 1);
+        OrderLine ol2 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 30.00)), 1);
+        Order order = new Order(Arrays.asList(ol0, ol1, ol2));
+
+        // when
+        order.removeLineItem(1);
+
+        // then
+        assertThat(order.totalCost()).isEqualTo(Money.of(CurrencyUnit.USD, 40.00));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/jpa/PersistOrderIntegrationTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.ddd.order.jpa;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+import java.util.Arrays;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+public class PersistOrderIntegrationTest {
+    @Autowired
+    private JpaOrderRepository repository;
+
+    @DisplayName("given order with two line items, when persist, then order is saved")
+    @Test
+    public void test() throws Exception {
+        // given
+        JpaOrder order = prepareTestOrderWithTwoLineItems();
+
+        // when
+        JpaOrder savedOrder = repository.save(order);
+
+        // then
+        JpaOrder foundOrder = repository.findById(savedOrder.getId())
+            .get();
+        assertThat(foundOrder.getOrderLines()).hasSize(2);
+    }
+
+    private JpaOrder prepareTestOrderWithTwoLineItems() {
+        JpaOrderLine ol0 = new JpaOrderLine(new JpaProduct(BigDecimal.valueOf(10.00), "USD"), 2);
+        JpaOrderLine ol1 = new JpaOrderLine(new JpaProduct(BigDecimal.valueOf(5.00), "USD"), 10);
+        return new JpaOrder(Arrays.asList(ol0, ol1));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/jpa/ViolateOrderBusinessRulesTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.ddd.order.jpa;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+public class ViolateOrderBusinessRulesTest {
+    @DisplayName("given two non-zero order line items, when create an order with them, it's possible to set total cost to zero")
+    @Test
+    void test() throws Exception {
+        // given
+        // available products
+        JpaProduct lungChingTea = new JpaProduct(BigDecimal.valueOf(10.00), "USD");
+        JpaProduct gyokuroMiyazakiTea = new JpaProduct(BigDecimal.valueOf(20.00), "USD");
+        // Lung Ching tea order line
+        JpaOrderLine orderLine0 = new JpaOrderLine(lungChingTea, 2);
+        // Gyokuro Miyazaki tea order line
+        JpaOrderLine orderLine1 = new JpaOrderLine(gyokuroMiyazakiTea, 3);
+
+        // when
+        // create the order
+        JpaOrder order = new JpaOrder();
+        order.addLineItem(orderLine0);
+        order.addLineItem(orderLine1);
+        order.setTotalCost(BigDecimal.ZERO);
+        order.setCurrencyUnit("USD");
+
+        // then
+        // this doesn't look good...
+        assertThat(order.getTotalCost()).isEqualTo(BigDecimal.ZERO);
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/mongo/OrderMongoIntegrationTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.ddd.order.mongo;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+import com.baeldung.ddd.order.Order;
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.Product;
+
+@SpringJUnitConfig
+@SpringBootTest
+public class OrderMongoIntegrationTest {
+    @Autowired
+    private OrderMongoRepository repo;
+
+    @DisplayName("given order with two line items, when persist using mongo repository, then order is saved")
+    @Test
+    void test() throws Exception {
+        // given
+        Order order = prepareTestOrderWithTwoLineItems();
+
+        // when
+        repo.save(order);
+
+        // then
+        List<Order> foundOrders = repo.findAll();
+        assertThat(foundOrders).hasSize(1);
+        List<OrderLine> foundOrderLines = foundOrders.iterator()
+            .next()
+            .getOrderLines();
+        assertThat(foundOrderLines).hasSize(2);
+        assertThat(foundOrderLines).containsOnlyElementsOf(order.getOrderLines());
+    }
+
+    private Order prepareTestOrderWithTwoLineItems() {
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 2);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 5.00)), 10);
+        return new Order(Arrays.asList(ol0, ol1));
+    }
+}

pom.xml

@@ -522,6 +522,7 @@
 				<module>spring-jms</module>
 				<module>spring-jooq</module>
 				<module>persistence-modules/spring-jpa</module>
+				<module>ddd</module>
 				
 			</modules>