BAEL-8847: Generating HTTP Clients in Spring Boot from OpenAPI Spec (#18844)

* new maven execution. adds dependencies. adds jackson types dependencies

* adds test

* final version changes

* set main clas to spring boot plugin

Author: pedrolopes9-7

spring-boot-modules/spring-boot-openapi/pom.xml

@@ -60,6 +60,7 @@
                 <version>${openapi-generator.version}</version>
                 <executions>
                     <execution>
+                        <id>generate-quotes-api</id>
                         <goals>
                             <goal>generate</goal>
                         </goals>
@@ -80,13 +81,40 @@
                                 <modelPackage>com.baeldung.tutorials.openapi.quotes.api.model</modelPackage>
                                 <documentationProvider>source</documentationProvider>
                             </configOptions>
+                            <generateApiTests>false</generateApiTests>
+                            <generateModelTests>false</generateModelTests>
+                            <supportingFilesToGenerate>ApiUtil.java</supportingFilesToGenerate>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>generate-weather-api</id>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                        <configuration>
+                            <inputSpec>${project.basedir}/src/main/resources/api/weatherapi.yaml</inputSpec>
+                            <generatorName>spring</generatorName>
+                            <configOptions>
+                                <openApiNullable>false</openApiNullable>
+                                <useJakartaEe>false</useJakartaEe>
+                                <annotationLibrary>none</annotationLibrary>
+                                <documentationProvider>none</documentationProvider>
+                                <apiPackage>com.baeldung.tutorials.openapi.generatehttpclients.api</apiPackage>
+                                <modelPackage>com.baeldung.tutorials.openapi.generatehttpclients.api.model</modelPackage>
+                            </configOptions>
+                            <generateApiTests>false</generateApiTests>
+                            <generateModelTests>false</generateModelTests>
+                            <supportingFilesToGenerate>ApiUtil.java</supportingFilesToGenerate>
                         </configuration>
                     </execution>
                 </executions>
             </plugin>
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
+                <configuration>
+                    <mainClass>com.baeldung.tutorials.openapi.generatehttpclients.GenerateHttpClientSpringApplication</mainClass>
+                </configuration>
             </plugin>
         </plugins>
     </build>

spring-boot-modules/spring-boot-openapi/src/main/java/com/baeldung/tutorials/openapi/generatehttpclients/GenerateHttpClientSpringApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.tutorials.openapi.generatehttpclients;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class GenerateHttpClientSpringApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(GenerateHttpClientSpringApplication.class, args);
+
+    }
+}

spring-boot-modules/spring-boot-openapi/src/main/java/com/baeldung/tutorials/openapi/generatehttpclients/service/GetWeatherService.java

@@ -0,0 +1,26 @@
+package com.baeldung.tutorials.openapi.generatehttpclients.service;
+
+import org.springframework.stereotype.Service;
+
+import com.baeldung.tutorials.openapi.generatehttpclients.api.WeatherApi;
+import com.baeldung.tutorials.openapi.generatehttpclients.api.model.WeatherResponse;
+
+@Service
+public class GetWeatherService {
+
+    private final WeatherApi weatherApi;
+
+    public GetWeatherService(WeatherApi weatherApi) {
+        this.weatherApi = weatherApi;
+    }
+
+    public WeatherResponse getCurrentWeather(String city, String units) {
+        var response = weatherApi.getCurrentWeather(city, units);
+
+        if (response.getStatusCodeValue() < 399) {
+            return response.getBody();
+        }
+
+        throw new RuntimeException("Failed to get current weather for " + city);
+    }
+}

spring-boot-modules/spring-boot-openapi/src/main/resources/api/weatherapi.yaml

@@ -0,0 +1,73 @@
+openapi: 3.0.3
+info:
+  title: Current Weather API
+  description: |
+    Get real-time weather information for cities worldwide.
+  version: 1.0.0
+
+paths:
+  /weather:
+    get:
+      summary: Get current weather data
+      description: Retrieve current weather information for a specified city
+      operationId: getCurrentWeather
+      parameters:
+        - name: city
+          in: query
+          required: true
+          schema:
+            type: string
+        - name: units
+          in: query
+          required: false
+          schema:
+            type: string
+            enum: [ celsius, fahrenheit ]
+            default: celsius
+      responses:
+        '200':
+          description: Successful weather data retrieval
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/WeatherResponse'
+        '404':
+          description: City not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+
+components:
+  schemas:
+    WeatherResponse:
+      type: object
+      required:
+        - location
+      properties:
+        current:
+          type: object
+          required:
+            - temperature
+            - units
+          properties:
+            temperature:
+              type: number
+              format: double
+            units:
+              type: string
+              enum: [ celsius, fahrenheit ]
+            timestamp:
+              type: string
+              format: date-time
+
+    ErrorResponse:
+      type: object
+      required:
+        - code
+        - message
+      properties:
+        code:
+          type: string
+        message:
+          type: string

spring-boot-modules/spring-boot-openapi/src/main/resources/application.yaml

@@ -2,4 +2,8 @@
 logging:
   level:
     root: INFO
-    org.springframework: INFO
+    org.springframework: INFO
+
+openapi:
+  currentWeather:
+    base-path: https://localhost:8080

spring-boot-modules/spring-boot-openapi/src/test/java/com/baeldung/tutorials/openapi/generatehttpclients/WeatherApiUnitTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.tutorials.openapi.generatehttpclients;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.when;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+
+import com.baeldung.tutorials.openapi.generatehttpclients.api.WeatherApi;
+import com.baeldung.tutorials.openapi.generatehttpclients.api.model.WeatherResponse;
+import com.baeldung.tutorials.openapi.generatehttpclients.api.model.WeatherResponseCurrent;
+import com.baeldung.tutorials.openapi.generatehttpclients.service.GetWeatherService;
+
+@ExtendWith(MockitoExtension.class)
+class WeatherApiUnitTest {
+
+    private GetWeatherService weatherService;
+
+    @Mock
+    private WeatherApi weatherApi;
+
+    @BeforeEach
+    void setUp() {
+        weatherService = new GetWeatherService(weatherApi);
+    }
+
+    @Test
+    void givenOkStatus_whenCallingWeatherApi_thenReturnCurrentWeather() {
+        when(weatherApi.getCurrentWeather("London", "celsius")).thenReturn(
+            new ResponseEntity<>(new WeatherResponse().current(new WeatherResponseCurrent(455d, WeatherResponseCurrent.UnitsEnum.CELSIUS)), HttpStatus.OK));
+
+        var weather = weatherService.getCurrentWeather("London", "celsius");
+
+        assertThat(weather.getCurrent()
+            .getTemperature()).isEqualTo(455d);
+        assertThat(weather.getCurrent()
+            .getUnits()).isEqualTo(WeatherResponseCurrent.UnitsEnum.CELSIUS);
+    }
+
+    @Test
+    void givenBadRequestStatus_whenCallingWeatherApi_thenReturnError() {
+        when(weatherApi.getCurrentWeather("London", "celsius")).thenReturn(new ResponseEntity<>(HttpStatus.BAD_REQUEST));
+
+        assertThrows(RuntimeException.class, () -> weatherService.getCurrentWeather("London", "celsius"));
+    }
+}