feat: add product service resolver

graphql.gateway/src/main/java/com/pooranjoyb/graphql/gateway/client/BaseWebClient.java

@@ -37,6 +37,18 @@ public <T> T getObject(String baseUrl, String uri, Class<T> responseType) {
                 .block();
     }
 
+    public <T, R> T post(String baseUrl, String uri, R requestBody, Class<T> responseType) {
+        return webClientBuilder
+                .baseUrl(baseUrl)
+                .build()
+                .post()
+                .uri(uri)
+                .bodyValue(requestBody)
+                .retrieve()
+                .bodyToMono(responseType)
+                .block();
+    }
+
     public void delete(String baseUrl, String uri) {
         webClientBuilder
                 .baseUrl(baseUrl)

graphql.gateway/src/main/java/com/pooranjoyb/graphql/gateway/client/ProductServiceClient.java

@@ -0,0 +1,32 @@
+package com.pooranjoyb.graphql.gateway.client;
+
+import com.pooranjoyb.graphql.gateway.core.Constants;
+import com.pooranjoyb.graphql.gateway.dto.ProductDto;
+import com.pooranjoyb.graphql.gateway.dto.ProductRequestDto;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+@Component
+@RequiredArgsConstructor
+public class ProductServiceClient {
+
+    private final BaseWebClient baseWebClient;
+
+    @Value("${product.service.url}")
+    private String productServiceUrl;
+
+    public List<ProductDto> getProducts() {
+        return baseWebClient.getList(productServiceUrl, Constants.PRODUCT_GET_PRODUCTS, ProductDto.class);
+    }
+
+    public ProductDto createProduct(ProductRequestDto productRequestDto) {
+        return baseWebClient.post(
+                productServiceUrl,
+                Constants.PRODUCT_CREATE_PRODUCT,
+                productRequestDto,
+                ProductDto.class);
+    }
+}

graphql.gateway/src/main/java/com/pooranjoyb/graphql/gateway/core/Constants.java

@@ -7,4 +7,6 @@ public class Constants {
     public static String ORDER_GET_ORDERS = "/orders";
     public static String ORDER_GET_BY_ID = "/orders/{id}";
     public static String ORDER_DELETE_BY_ID = "/orders/{id}";
+    public static String PRODUCT_GET_PRODUCTS = "/products";
+    public static String PRODUCT_CREATE_PRODUCT = "/products";
 }

graphql.gateway/src/main/java/com/pooranjoyb/graphql/gateway/resolver/ProductResolver.java

@@ -0,0 +1,29 @@
+package com.pooranjoyb.graphql.gateway.resolver;
+
+import com.pooranjoyb.graphql.gateway.client.ProductServiceClient;
+import com.pooranjoyb.graphql.gateway.dto.ProductDto;
+import com.pooranjoyb.graphql.gateway.dto.ProductRequestDto;
+import lombok.RequiredArgsConstructor;
+import org.springframework.graphql.data.method.annotation.Argument;
+import org.springframework.graphql.data.method.annotation.MutationMapping;
+import org.springframework.graphql.data.method.annotation.QueryMapping;
+import org.springframework.stereotype.Controller;
+
+import java.util.List;
+
+@Controller
+@RequiredArgsConstructor
+public class ProductResolver {
+
+    private final ProductServiceClient productServiceClient;
+
+    @QueryMapping
+    public List<ProductDto> getProducts() {
+        return productServiceClient.getProducts();
+    }
+
+    @MutationMapping
+    public ProductDto createProduct(@Argument("product") ProductRequestDto productRequestDto) {
+        return productServiceClient.createProduct(productRequestDto);
+    }
+}

graphql.gateway/src/main/resources/graphql/schema.graphqls

@@ -9,8 +9,32 @@ type Order {
     status: String
 }
 
+type Product {
+    name: String,
+    inStock: Boolean,
+    image: String,
+    description: String,
+    brand: String,
+    rating: Int
+}
+
+input ProductInput {
+    name: String!,
+    stock: Int!,
+    image: String,
+    description: String,
+    brand: String,
+    rating: Int,
+    sku: Int!
+}
+
 # queries
 type Query {
     getOrders: [Order],
-    createOrder: Order
-}
+    createOrder: Order,
+    getProducts: [Product]
+}
+
+type Mutation {
+    createProduct(product: ProductInput!): Product
+}

graphql.gateway/src/test/java/com/pooranjoyb/graphql/gateway/client/ProductServiceClientTests.java

@@ -0,0 +1,65 @@
+package com.pooranjoyb.graphql.gateway.client;
+
+import com.pooranjoyb.graphql.gateway.core.Constants;
+import com.pooranjoyb.graphql.gateway.dto.ProductDto;
+import com.pooranjoyb.graphql.gateway.dto.ProductRequestDto;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class ProductServiceClientTests {
+
+    private final BaseWebClient baseWebClient = mock(BaseWebClient.class);
+    private final ProductServiceClient productServiceClient = new ProductServiceClient(baseWebClient);
+
+    ProductServiceClientTests() {
+        ReflectionTestUtils.setField(productServiceClient, "productServiceUrl", "http://product-service");
+    }
+
+    @Test
+    void getProductsCallsProductServiceListEndpoint() {
+        ProductDto product = ProductDto.builder().name("monitor").inStock(true).build();
+        when(baseWebClient.getList(
+                "http://product-service",
+                Constants.PRODUCT_GET_PRODUCTS,
+                ProductDto.class)).thenReturn(List.of(product));
+
+        List<ProductDto> products = productServiceClient.getProducts();
+
+        assertThat(products).containsExactly(product);
+        verify(baseWebClient).getList(
+                "http://product-service",
+                Constants.PRODUCT_GET_PRODUCTS,
+                ProductDto.class);
+    }
+
+    @Test
+    void createProductPostsProductPayloadToProductService() {
+        ProductRequestDto request = ProductRequestDto.builder()
+                .name("monitor")
+                .stock(10L)
+                .sku(12345L)
+                .build();
+        ProductDto createdProduct = ProductDto.builder().name("monitor").inStock(true).build();
+        when(baseWebClient.post(
+                "http://product-service",
+                Constants.PRODUCT_CREATE_PRODUCT,
+                request,
+                ProductDto.class)).thenReturn(createdProduct);
+
+        ProductDto response = productServiceClient.createProduct(request);
+
+        assertThat(response).isEqualTo(createdProduct);
+        verify(baseWebClient).post(
+                "http://product-service",
+                Constants.PRODUCT_CREATE_PRODUCT,
+                request,
+                ProductDto.class);
+    }
+}

graphql.gateway/src/test/java/com/pooranjoyb/graphql/gateway/resolver/ProductResolverTests.java

@@ -0,0 +1,56 @@
+package com.pooranjoyb.graphql.gateway.resolver;
+
+import com.pooranjoyb.graphql.gateway.client.ProductServiceClient;
+import com.pooranjoyb.graphql.gateway.dto.ProductDto;
+import com.pooranjoyb.graphql.gateway.dto.ProductRequestDto;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class ProductResolverTests {
+
+    private final ProductServiceClient productServiceClient = mock(ProductServiceClient.class);
+    private final ProductResolver productResolver = new ProductResolver(productServiceClient);
+
+    @Test
+    void getProductsDelegatesToProductServiceClient() {
+        ProductDto product = ProductDto.builder()
+                .name("monitor")
+                .inStock(true)
+                .brand("Acme")
+                .build();
+        when(productServiceClient.getProducts()).thenReturn(List.of(product));
+
+        List<ProductDto> products = productResolver.getProducts();
+
+        assertThat(products).containsExactly(product);
+        verify(productServiceClient).getProducts();
+    }
+
+    @Test
+    void createProductDelegatesToProductServiceClient() {
+        ProductRequestDto request = ProductRequestDto.builder()
+                .name("monitor")
+                .stock(10L)
+                .image("monitor.png")
+                .description("27 inch display")
+                .brand("Acme")
+                .rating(5L)
+                .sku(12345L)
+                .build();
+        ProductDto createdProduct = ProductDto.builder()
+                .name("monitor")
+                .inStock(true)
+                .brand("Acme")
+                .build();
+        when(productServiceClient.createProduct(request)).thenReturn(createdProduct);
+
+        assertThat(productResolver.createProduct(request)).isEqualTo(createdProduct);
+        verify(productServiceClient).createProduct(request);
+    }
+}