feat(customer-service): add full CRUD support with type-safe generic responses

- Implemented complete CRUD endpoints in CustomerController
- Introduced dedicated DTOs for create, update, list, and delete responses
- Added CustomerControllerAdvice for consistent error handling
- Enhanced unit tests for controller and service layers
- Updated README.md with CRUD usage examples
- Bumped service version to 0.3.0 to reflect new functionality

Author: barissayli

README.md

@@ -13,14 +13,16 @@
 </p>
 
 **Type-safe client generation with Spring Boot & OpenAPI using generics.**
-This repository demonstrates how to teach OpenAPI Generator to work with generics in order to avoid boilerplate, reduce duplicated wrappers, and keep client code clean.
+This repository demonstrates how to teach OpenAPI Generator to work with generics in order to avoid boilerplate, reduce
+duplicated wrappers, and keep client code clean.
 
 ---
 
 ## 🚀 Problem Statement
 
 Most backend teams standardize responses with a generic wrapper like `ApiResponse<T>`.
-However, **OpenAPI Generator does not natively support generics** — instead, it generates one wrapper per endpoint (duplicating fields like `status`, `message`, and `errors`).
+However, **OpenAPI Generator does not natively support generics** — instead, it generates one wrapper per endpoint
+(duplicating fields like `status`, `message`, and `errors`).
 
 This creates:
 
@@ -60,7 +62,7 @@ Use the generated API:
 
 ```java
 ApiClientResponse<CustomerCreateResponse> response =
-    customerControllerApi.create(request);
+    customerControllerApi.createCustomer(request);
 ```
 
 ### 🖼 Demo Swagger Screenshot
@@ -75,6 +77,8 @@ And here’s the corresponding generated client class showing the generic wrappe
 
 ![Generated client wrapper](docs/images/generated-client-wrapper.png)
 
+---
+
 ## 🛠 Tech Stack & Features
 
 * 🚀 **Java 21** — modern language features
@@ -92,7 +96,7 @@ And here’s the corresponding generated client class showing the generic wrappe
 spring-boot-openapi-generics-clients/
  ├── customer-service/          # Sample Spring Boot microservice (API producer)
  ├── customer-service-client/   # Generated client using custom templates
- └── README.md
+ └── README.md                  # Root documentation
 ```
 
 ---
@@ -149,7 +153,7 @@ This pattern is useful when:
 
    ```java
    ApiClientResponse<CustomerCreateResponse> response =
-       customerControllerApi.create(request);
+       customerControllerApi.createCustomer(request);
    ```
 
 ---
@@ -174,5 +178,6 @@ If parameters include spaces or special characters, wrap them in quotes `"..."`.
 
 ## 💬 Feedback
 
-If you spot any mistakes in this README or have questions about the project, feel free to open an issue or start a discussion.
+If you spot any mistakes in this README or have questions about the project, feel free to open an issue or start a
+discussion.
 I’m happy to improve the documentation and clarify concepts further!

customer-service-client/README.md

@@ -1,18 +1,20 @@
 # customer-service-client
 
-Generated Java client for the demo **customer-service**, showcasing **type‑safe generic responses** with OpenAPI + a custom Mustache template (wrapping payloads in a reusable `ApiClientResponse<T>`).
+Generated Java client for the demo **customer-service**, showcasing **type-safe generic responses** with OpenAPI + a
+custom Mustache template (wrapping payloads in a reusable `ApiClientResponse<T>`).
 
-This module demonstrates how to evolve OpenAPI Generator with minimal customization to support generic response envelopes — avoiding duplicated wrappers and preserving strong typing.
+This module demonstrates how to evolve OpenAPI Generator with minimal customization to support generic response
+envelopes — avoiding duplicated wrappers and preserving strong typing.
 
 ---
 
 ## ✅ What You Get
 
 * Generated code using **OpenAPI Generator** (`restclient` with Spring Framework `RestClient`).
 * A reusable generic base: `io.github.bsayli.openapi.client.common.ApiClientResponse<T>`.
-* Thin wrappers per endpoint (e.g. `ApiResponseCustomerCreateResponse`) that extend the base.
-* Spring Boot configuration to auto‑expose the client as beans.
-* A focused integration test using **OkHttp MockWebServer**.
+* Thin wrappers per endpoint (e.g. `ApiResponseCustomerCreateResponse`, `ApiResponseCustomerUpdateResponse`).
+* Spring Boot configuration to auto-expose the client as beans.
+* Focused integration tests using **OkHttp MockWebServer** covering all CRUD endpoints.
 
 ---
 
@@ -23,14 +25,14 @@ This module demonstrates how to evolve OpenAPI Generator with minimal customizat
 ```bash
 cd customer-service
 mvn spring-boot:run
-# Service base URL: http://localhost:8084/customer
+# Service base URL: http://localhost:8084/customer-service
 ```
 
 2. **Pull the OpenAPI spec into this module**
 
 ```bash
 cd customer-service-client
-curl -s http://localhost:8084/customer/v3/api-docs.yaml \
+curl -s http://localhost:8084/customer-service/v3/api-docs.yaml \
   -o src/main/resources/customer-api-docs.yaml
 ```
 
@@ -83,7 +85,7 @@ public class CustomerApiClientConfig {
 **application.properties:**
 
 ```properties
-customer.api.base-url=http://localhost:8084/customer
+customer.api.base-url=http://localhost:8084/customer-service
 ```
 
 **Usage example:**
@@ -97,19 +99,19 @@ public void createCustomer() {
       .name("Jane Doe")
       .email("[email protected]");
 
-  var resp = customerApi.create(req); // ApiResponseCustomerCreateResponse
+  var resp = customerApi.createCustomer(req); // ApiResponseCustomerCreateResponse
 
-  System.out.println(resp.getStatus());                 // 201
+  System.out.println(resp.getStatus());                      // 201
   System.out.println(resp.getData().getCustomer().getName()); // "Jane Doe"
 }
 ```
 
 ### Option B — Manual Wiring (no Spring context)
 
 ```java
-var rest = RestClient.builder().baseUrl("http://localhost:8084/customer").build();
+var rest = RestClient.builder().baseUrl("http://localhost:8084/customer-service").build();
 var apiClient = new io.github.bsayli.openapi.client.generated.invoker.ApiClient(rest)
-    .setBasePath("http://localhost:8084/customer");
+    .setBasePath("http://localhost:8084/customer-service");
 var customerApi = new io.github.bsayli.openapi.client.generated.api.CustomerControllerApi(apiClient);
 ```
 
@@ -125,8 +127,7 @@ package io.github.bsayli.openapi.client.adapter.impl;
 import io.github.bsayli.openapi.client.adapter.CustomerClientAdapter;
 import io.github.bsayli.openapi.client.common.ApiClientResponse;
 import io.github.bsayli.openapi.client.generated.api.CustomerControllerApi;
-import io.github.bsayli.openapi.client.generated.dto.CustomerCreateRequest;
-import io.github.bsayli.openapi.client.generated.dto.CustomerCreateResponse;
+import io.github.bsayli.openapi.client.generated.dto.*;
 import org.springframework.stereotype.Service;
 
 @Service
@@ -139,8 +140,28 @@ public class CustomerClientAdapterImpl implements CustomerClientAdapter {
     }
 
     @Override
-    public ApiClientResponse<CustomerCreateResponse> create(CustomerCreateRequest request) {
-        return customerControllerApi.create(request);
+    public ApiClientResponse<CustomerCreateResponse> createCustomer(CustomerCreateRequest request) {
+        return customerControllerApi.createCustomer(request);
+    }
+
+    @Override
+    public ApiClientResponse<CustomerDto> getCustomer(Integer customerId) {
+        return customerControllerApi.getCustomer(customerId);
+    }
+
+    @Override
+    public ApiClientResponse<CustomerListResponse> getCustomers() {
+        return customerControllerApi.getCustomers();
+    }
+
+    @Override
+    public ApiClientResponse<CustomerUpdateResponse> updateCustomer(Integer customerId, CustomerUpdateRequest request) {
+        return customerControllerApi.updateCustomer(customerId, request);
+    }
+
+    @Override
+    public ApiClientResponse<CustomerDeleteResponse> deleteCustomer(Integer customerId) {
+        return customerControllerApi.deleteCustomer(customerId);
     }
 }
 ```
@@ -149,6 +170,7 @@ This ensures:
 
 * Generated code stays isolated.
 * Business code depends only on the adapter interface.
+* Naming conventions are consistent with the service (createCustomer, getCustomer, getCustomers, updateCustomer, deleteCustomer).
 
 ---
 
@@ -177,7 +199,7 @@ Integration test with MockWebServer:
 mvn -q -DskipITs=false test
 ```
 
-It enqueues a `201` response and asserts correct mapping into `ApiResponseCustomerCreateResponse`.
+It enqueues responses for **all CRUD operations** and asserts correct mapping into the respective wrappers (e.g. `ApiResponseCustomerCreateResponse`, `ApiResponseCustomerUpdateResponse`).
 
 ---
 

customer-service-client/pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>io.github.bsayli</groupId>
     <artifactId>customer-service-client</artifactId>
-    <version>0.2.1</version>
+    <version>0.3.0</version>
     <name>customer-service-client</name>
     <description>Generated client (RestClient) using generics-aware OpenAPI templates</description>
     <packaging>jar</packaging>
@@ -129,7 +129,8 @@
                             <invokerPackage>io.github.bsayli.openapi.client.generated.invoker</invokerPackage>
 
                             <!-- Use our custom templates that implement generics-aware wrappers -->
-                            <templateDirectory>${project.basedir}/src/main/resources/openapi-templates</templateDirectory>
+                            <templateDirectory>${project.basedir}/src/main/resources/openapi-templates
+                            </templateDirectory>
 
                             <!-- Keep output lean -->
                             <generateSupportingFiles>true</generateSupportingFiles>

customer-service-client/src/main/java/io/github/bsayli/openapi/client/adapter/CustomerClientAdapter.java

@@ -1,9 +1,12 @@
 package io.github.bsayli.openapi.client.adapter;
 
 import io.github.bsayli.openapi.client.common.ApiClientResponse;
-import io.github.bsayli.openapi.client.generated.dto.CustomerCreateRequest;
-import io.github.bsayli.openapi.client.generated.dto.CustomerCreateResponse;
+import io.github.bsayli.openapi.client.generated.dto.*;
 
 public interface CustomerClientAdapter {
-    ApiClientResponse<CustomerCreateResponse> create(CustomerCreateRequest request);
+  ApiClientResponse<CustomerCreateResponse> createCustomer(CustomerCreateRequest request);
+  ApiClientResponse<CustomerDto> getCustomer(Integer customerId);
+  ApiClientResponse<CustomerListResponse> getCustomers();
+  ApiClientResponse<CustomerUpdateResponse> updateCustomer(Integer customerId, CustomerUpdateRequest request);
+  ApiClientResponse<CustomerDeleteResponse> deleteCustomer(Integer customerId);
 }

customer-service-client/src/main/java/io/github/bsayli/openapi/client/adapter/config/CustomerApiClientConfig.java

@@ -10,20 +10,20 @@
 @Configuration
 public class CustomerApiClientConfig {
 
-    @Bean
-    public RestClient customerRestClient(RestClient.Builder builder,
-                                         @Value("${customer.api.base-url}") String baseUrl) {
-        return builder.baseUrl(baseUrl).build();
-    }
+  @Bean
+  public RestClient customerRestClient(
+      RestClient.Builder builder, @Value("${customer.api.base-url}") String baseUrl) {
+    return builder.baseUrl(baseUrl).build();
+  }
 
-    @Bean
-    public ApiClient customerApiClient(RestClient customerRestClient,
-                                       @Value("${customer.api.base-url}") String baseUrl) {
-        return new ApiClient(customerRestClient).setBasePath(baseUrl);
-    }
+  @Bean
+  public ApiClient customerApiClient(
+      RestClient customerRestClient, @Value("${customer.api.base-url}") String baseUrl) {
+    return new ApiClient(customerRestClient).setBasePath(baseUrl);
+  }
 
-    @Bean
-    public CustomerControllerApi customerControllerApi(ApiClient customerApiClient) {
-        return new CustomerControllerApi(customerApiClient);
-    }
-}
+  @Bean
+  public CustomerControllerApi customerControllerApi(ApiClient customerApiClient) {
+    return new CustomerControllerApi(customerApiClient);
+  }
+}

customer-service-client/src/main/java/io/github/bsayli/openapi/client/adapter/impl/CustomerClientAdapterImpl.java

@@ -5,19 +5,45 @@
 import io.github.bsayli.openapi.client.generated.api.CustomerControllerApi;
 import io.github.bsayli.openapi.client.generated.dto.CustomerCreateRequest;
 import io.github.bsayli.openapi.client.generated.dto.CustomerCreateResponse;
+import io.github.bsayli.openapi.client.generated.dto.CustomerDeleteResponse;
+import io.github.bsayli.openapi.client.generated.dto.CustomerDto;
+import io.github.bsayli.openapi.client.generated.dto.CustomerListResponse;
+import io.github.bsayli.openapi.client.generated.dto.CustomerUpdateRequest;
+import io.github.bsayli.openapi.client.generated.dto.CustomerUpdateResponse;
 import org.springframework.stereotype.Service;
 
 @Service
 public class CustomerClientAdapterImpl implements CustomerClientAdapter {
 
-    private final CustomerControllerApi customerControllerApi;
+  private final CustomerControllerApi customerControllerApi;
 
-    public CustomerClientAdapterImpl(CustomerControllerApi customerControllerApi) {
-        this.customerControllerApi = customerControllerApi;
-    }
+  public CustomerClientAdapterImpl(CustomerControllerApi customerControllerApi) {
+    this.customerControllerApi = customerControllerApi;
+  }
 
-    @Override
-    public ApiClientResponse<CustomerCreateResponse> create(CustomerCreateRequest request) {
-        return customerControllerApi.create(request);
-    }
+  @Override
+  public ApiClientResponse<CustomerCreateResponse> createCustomer(CustomerCreateRequest request) {
+    return customerControllerApi.createCustomer(request);
+  }
+
+  @Override
+  public ApiClientResponse<CustomerDto> getCustomer(Integer customerId) {
+    return customerControllerApi.getCustomer(customerId);
+  }
+
+  @Override
+  public ApiClientResponse<CustomerListResponse> getCustomers() {
+    return customerControllerApi.getCustomers();
+  }
+
+  @Override
+  public ApiClientResponse<CustomerUpdateResponse> updateCustomer(
+          Integer customerId, CustomerUpdateRequest request) {
+    return customerControllerApi.updateCustomer(customerId, request);
+  }
+
+  @Override
+  public ApiClientResponse<CustomerDeleteResponse> deleteCustomer(Integer customerId) {
+    return customerControllerApi.deleteCustomer(customerId);
+  }
 }

customer-service-client/src/main/java/io/github/bsayli/openapi/client/common/ApiClientError.java

@@ -1,4 +1,3 @@
 package io.github.bsayli.openapi.client.common;
 
-public record ApiClientError(String errorCode, String message) {
-}
+public record ApiClientError(String errorCode, String message) {}