Update Command API

- Adjust PlaceOrderCommand to only construct the order
- Introduce AddProductCommand to be able to add several products to an
order
- Introduce IncrementProductCountCommand to increase the number of
product instances for a given Order
- Introduce DecrementProductCountCommand to increase the number of
product instances for a given Order

#BAEL-4767

axon/src/main/java/com/baeldung/axon/coreapi/commands/AddProductCommand.java

@@ -0,0 +1,50 @@
+package com.baeldung.axon.coreapi.commands;
+
+import org.axonframework.modelling.command.TargetAggregateIdentifier;
+
+import java.util.Objects;
+
+public class AddProductCommand {
+
+    @TargetAggregateIdentifier
+    private final String orderId;
+    private final String productId;
+
+    public AddProductCommand(String orderId, String productId) {
+        this.orderId = orderId;
+        this.productId = productId;
+    }
+
+    public String getOrderId() {
+        return orderId;
+    }
+
+    public String getProductId() {
+        return productId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        AddProductCommand that = (AddProductCommand) o;
+        return Objects.equals(orderId, that.orderId) && Objects.equals(productId, that.productId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(orderId, productId);
+    }
+
+    @Override
+    public String toString() {
+        return "AddProductCommand{" +
+                "orderId='" + orderId + '\'' +
+                ", productId='" + productId + '\'' +
+                '}';
+    }
+}

axon/src/main/java/com/baeldung/axon/coreapi/commands/DecrementProductCountCommand.java

@@ -0,0 +1,50 @@
+package com.baeldung.axon.coreapi.commands;
+
+import org.axonframework.modelling.command.TargetAggregateIdentifier;
+
+import java.util.Objects;
+
+public class DecrementProductCountCommand {
+
+    @TargetAggregateIdentifier
+    private final String orderId;
+    private final String productId;
+
+    public DecrementProductCountCommand(String orderId, String productId) {
+        this.orderId = orderId;
+        this.productId = productId;
+    }
+
+    public String getOrderId() {
+        return orderId;
+    }
+
+    public String getProductId() {
+        return productId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        DecrementProductCountCommand that = (DecrementProductCountCommand) o;
+        return Objects.equals(orderId, that.orderId) && Objects.equals(productId, that.productId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(orderId, productId);
+    }
+
+    @Override
+    public String toString() {
+        return "DecrementProductCountCommand{" +
+                "orderId='" + orderId + '\'' +
+                ", productId='" + productId + '\'' +
+                '}';
+    }
+}

axon/src/main/java/com/baeldung/axon/coreapi/commands/IncrementProductCountCommand.java

@@ -0,0 +1,50 @@
+package com.baeldung.axon.coreapi.commands;
+
+import org.axonframework.modelling.command.TargetAggregateIdentifier;
+
+import java.util.Objects;
+
+public class IncrementProductCountCommand {
+
+    @TargetAggregateIdentifier
+    private final String orderId;
+    private final String productId;
+
+    public IncrementProductCountCommand(String orderId, String productId) {
+        this.orderId = orderId;
+        this.productId = productId;
+    }
+
+    public String getOrderId() {
+        return orderId;
+    }
+
+    public String getProductId() {
+        return productId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        IncrementProductCountCommand that = (IncrementProductCountCommand) o;
+        return Objects.equals(orderId, that.orderId) && Objects.equals(productId, that.productId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(orderId, productId);
+    }
+
+    @Override
+    public String toString() {
+        return "IncrementProductCountCommand{" +
+                "orderId='" + orderId + '\'' +
+                ", productId='" + productId + '\'' +
+                '}';
+    }
+}

axon/src/main/java/com/baeldung/axon/coreapi/commands/PlaceOrderCommand.java

@@ -1,51 +1,43 @@
 package com.baeldung.axon.coreapi.commands;
 
-import java.util.Objects;
-
 import org.axonframework.modelling.command.TargetAggregateIdentifier;
 
+import java.util.Objects;
+
 public class PlaceOrderCommand {
 
     @TargetAggregateIdentifier
     private final String orderId;
-    private final String product;
 
-    public PlaceOrderCommand(String orderId, String product) {
+    public PlaceOrderCommand(String orderId) {
         this.orderId = orderId;
-        this.product = product;
     }
 
     public String getOrderId() {
         return orderId;
     }
 
-    public String getProduct() {
+    @Override
-        return product;
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        PlaceOrderCommand that = (PlaceOrderCommand) o;
+        return Objects.equals(orderId, that.orderId);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(orderId, product);
+        return Objects.hash(orderId);
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) {
-            return true;
-        }
-        if (obj == null || getClass() != obj.getClass()) {
-            return false;
-        }
-        final PlaceOrderCommand other = (PlaceOrderCommand) obj;
-        return Objects.equals(this.orderId, other.orderId)
-                && Objects.equals(this.product, other.product);
     }
 
     @Override
     public String toString() {
         return "PlaceOrderCommand{" +
                 "orderId='" + orderId + '\'' +
-                ", product='" + product + '\'' +
                 '}';
     }
 }