[Third week] Domain model Active record

build.gradle.kts

@@ -19,6 +19,9 @@ dependencies {
     implementation("org.springframework.boot:spring-boot-starter-web")
     implementation("org.springframework.boot:spring-boot-starter-validation")
 
+    implementation("org.mongodb:mongodb-driver-core:5.2.0")
+    implementation("org.mongodb:mongodb-driver-sync:5.2.0")
+
     developmentOnly("org.springframework.boot:spring-boot-devtools")
 
     testImplementation("org.springframework.boot:spring-boot-starter-test")

src/main/java/com/example/demo/Application.java

@@ -1,11 +1,31 @@
 package com.example.demo;
 
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+import com.mongodb.client.MongoDatabase;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
 
 @SpringBootApplication
 public class Application {
     public static void main(String[] args) {
         SpringApplication.run(Application.class, args);
     }
+
+    @Bean
+    public MongoClient mongoClient(
+            @Value("${mongodb.url}") String url
+    ) {
+        return MongoClients.create(url);
+    }
+
+    @Bean
+    public MongoDatabase mongoDatabase(
+            MongoClient mongoClient,
+            @Value("${mongodb.database}") String database
+    ) {
+        return mongoClient.getDatabase(database);
+    }
 }

src/main/java/com/example/demo/application/CartService.java

@@ -0,0 +1,60 @@
+package com.example.demo.application;
+
+import com.example.demo.infrastructure.LineItemDAO;
+import com.example.demo.infrastructure.ProductDAO;
+import com.example.demo.models.Cart;
+import com.example.demo.models.LineItem;
+import com.example.demo.models.Product;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+
+@Service
+public class CartService {
+
+
+    private final LineItemDAO lineItemDAO;
+    private final ProductDAO productDAO;
+
+    public CartService(
+            LineItemDAO lineItemDAO,
+            ProductDAO productDAO
+    ) {
+        this.lineItemDAO = lineItemDAO;
+        this.productDAO = productDAO;
+    }
+
+    public Cart getCart() {
+        List<LineItem> lineItems = lineItemDAO.findAll();
+
+        lineItems.forEach(lineItem -> {
+            String productId = lineItem.getProductId();
+            Product product = productDAO.find(productId);
+
+
+            lineItem.setProduct(product);
+        });
+
+
+        return new Cart(lineItems);
+    }
+
+    public void addProduct(String productId, int quantity) {
+        List<LineItem> lineItems = lineItemDAO.findAll();
+
+        LineItem lineItem = lineItems.stream()
+                .filter(i -> i.getProductId().equals(productId))
+                .findFirst()
+                .orElse(null);
+
+        if (lineItem == null) {
+            lineItem = new LineItem(productId, quantity);
+            lineItemDAO.add(lineItem);
+            return;
+        }
+
+        lineItem.addQuantity(quantity);
+
+        lineItemDAO.update(lineItem);
+    }
+}

src/main/java/com/example/demo/controllers/CartController.java

@@ -1,14 +1,42 @@
 package com.example.demo.controllers;
 
+import com.example.demo.application.CartService;
+import com.example.demo.controllers.dtos.CartDto;
+import com.example.demo.models.Cart;
+import com.example.demo.models.LineItem;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 @RestController
 @RequestMapping("/cart")
 public class CartController {
+    private final CartService cartService;
+
+    public CartController(CartService cartService) {
+        this.cartService = cartService;
+    }
+
+
     @GetMapping
-    String detail() {
-        return "";
+    CartDto detail() {
+        Cart cart = cartService.getCart();
+
+        return new CartDto(
+                cart.getLineItems().stream().map(this::mapToDto).toList(),
+                cart.getTotalPrice()
+        );
+    }
+
+    private CartDto.LineItemDto mapToDto(LineItem lineItem) {
+        return new CartDto.LineItemDto(
+                lineItem.getId(),
+                lineItem.getProductId(),
+                lineItem.getProductName(),
+                lineItem.getUnitPrice(),
+                lineItem.getQuantity(),
+                lineItem.getTotalPrice()
+        );
     }
+
 }

src/main/java/com/example/demo/controllers/LineItemController.java

@@ -1,17 +1,32 @@
 package com.example.demo.controllers;
 
+import com.example.demo.application.CartService;
+import com.example.demo.controllers.dtos.AddProductToCartDto;
+import jakarta.validation.Valid;
 import org.springframework.http.HttpStatus;
 import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestController;
 
 @RestController
 @RequestMapping("/cart/line-items")
 public class LineItemController {
+    private final CartService cartService;
+
+    public LineItemController(CartService cartService) {
+        this.cartService = cartService;
+    }
+
     @PostMapping
     @ResponseStatus(HttpStatus.CREATED)
-    void create() {
-        //
+    void create(
+            @Valid @RequestBody AddProductToCartDto addProductToCartDto
+    ) {
+        cartService.addProduct(
+                addProductToCartDto.productId(),
+                addProductToCartDto.quantity()
+        );
     }
 }

src/main/java/com/example/demo/controllers/dtos/AddProductToCartDto.java

@@ -0,0 +1,14 @@
+package com.example.demo.controllers.dtos;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Positive;
+
+public record AddProductToCartDto(
+        @NotBlank
+        String productId,
+
+        @Positive
+        int quantity
+) {
+
+}

src/main/java/com/example/demo/controllers/dtos/CartDto.java

@@ -0,0 +1,18 @@
+package com.example.demo.controllers.dtos;
+
+import java.util.List;
+
+public record CartDto(
+        List<LineItemDto> lineItems,
+        int totalPrice
+) {
+    public record LineItemDto(
+            String id,
+            String productId,
+            String productName,
+            int unitPrice,
+            int quantity,
+            int totalPrice
+    ) {
+    }
+}

src/main/java/com/example/demo/infrastructure/LineItemDAO.java

@@ -0,0 +1,60 @@
+package com.example.demo.infrastructure;
+
+import com.example.demo.models.LineItem;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+import com.mongodb.client.model.Filters;
+import com.mongodb.client.model.Updates;
+import org.bson.Document;
+import org.bson.types.ObjectId;
+import org.springframework.stereotype.Component;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@Component
+public class LineItemDAO {
+    private final MongoCollection<Document> collection;
+
+    public LineItemDAO(MongoDatabase mongoDatabase) {
+        this.collection = mongoDatabase.getCollection("line_items");
+    }
+
+    public List<LineItem> findAll() {
+
+        List<Document> documents = new ArrayList<>();
+
+        collection.find().into(documents);
+        return documents.stream()
+                .map(this::mapToModel)
+                .toList();
+    }
+
+    private LineItem mapToModel(Document document) {
+        return new LineItem(
+                document.getObjectId("_id").toString(),
+                document.getString("product_id"),
+                document.getInteger("quantity")
+        );
+    }
+
+    public void add(LineItem lineItem) {
+        Document document = new Document()
+                .append("product_id", lineItem.getProductId())
+                .append("quantity", lineItem.getQuantity());
+
+        collection.insertOne(document);
+    }
+
+
+    public void update(LineItem lineItem) {
+        collection.updateOne(
+                Filters.eq("_id", new ObjectId(lineItem.getId())),
+                Updates.combine(
+                        Updates.set("product_id", lineItem.getProductId()),
+                        Updates.set("quantity", lineItem.getQuantity())
+                )
+        );
+    }
+
+}

src/main/java/com/example/demo/infrastructure/ProductDAO.java

@@ -0,0 +1,35 @@
+package com.example.demo.infrastructure;
+
+import com.example.demo.models.Product;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+import com.mongodb.client.model.Filters;
+import org.bson.Document;
+import org.bson.types.ObjectId;
+import org.springframework.stereotype.Component;
+
+@Component
+public class ProductDAO {
+    private final MongoCollection<Document> collection;
+
+    public ProductDAO(MongoDatabase mongoDatabase) {
+        this.collection = mongoDatabase.getCollection("line_items");
+    }
+
+
+    public Product find(String productId) {
+        Document document = collection.find(
+                Filters.eq("_id", new ObjectId(productId))
+        ).first();
+
+        if (document == null) {
+            return null;
+        }
+
+        return new Product(
+                document.getObjectId("_id").toString(),
+                document.getString("name"),
+                document.getInteger("price")
+        );
+    }
+}

src/main/java/com/example/demo/models/Cart.java

@@ -0,0 +1,22 @@
+package com.example.demo.models;
+
+import java.util.Collections;
+import java.util.List;
+
+public class Cart {
+    private List<LineItem> lineItems;
+
+    public Cart(List<LineItem> lineItems) {
+        this.lineItems = lineItems;
+    }
+
+    public List<LineItem> getLineItems() {
+        return Collections.unmodifiableList(lineItems);
+    }
+
+    public int getTotalPrice() {
+        return lineItems.stream()
+                .mapToInt(LineItem::getTotalPrice)
+                .sum();
+    }
+}

src/main/java/com/example/demo/models/LineItem.java

@@ -0,0 +1,58 @@
+package com.example.demo.models;
+
+public class LineItem {
+    //Similar to DB schema
+    private String id = null;
+    private String productId;
+    private int quantity;
+
+    private String productName;
+    private int unitPrice;
+    private int totalPrice;
+
+    public LineItem(String productId, int quantity) {
+        this.productId = productId;
+        this.quantity = quantity;
+    }
+
+    public LineItem(String id, String productId, int quantity) {
+        this.id = id;
+        this.productId = productId;
+        this.quantity = quantity;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public String getProductId() {
+        return productId;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public int getUnitPrice() {
+        return unitPrice;
+    }
+
+    //business logic
+
+    public void addQuantity(int quantity) {
+        this.quantity += quantity;
+    }
+
+    public int getTotalPrice() {
+        return unitPrice * quantity;
+    }
+
+    public void setProduct(Product product) {
+        this.productName = product.getName();
+        this.unitPrice = product.getPrice();
+    }
+}