[BAEL-6689] code for zipwhen

spring-5-webflux-2/src/main/java/com/baeldung/webflux/zipwhen/model/User.java

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+package com.baeldung.webflux.zipwhen.model;
+
+public class User {
+
+    private final String id;
+    private final String email;
+
+    public User(String id, String email) {
+        this.id = id;
+        this.email = email;
+
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+}

spring-5-webflux-2/src/main/java/com/baeldung/webflux/zipwhen/service/DatabaseService.java

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+package com.baeldung.webflux.zipwhen.service;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import com.baeldung.webflux.zipwhen.model.User;
+
+import reactor.core.publisher.Mono;
+
+public class DatabaseService {
+    private Map<String, User> dataStore = new ConcurrentHashMap<>();
+
+    public Mono<Boolean> saveUserData(User user) {
+        return Mono.create(sink -> {
+            try {
+                dataStore.put(user.getId(), user);
+                sink.success(true);
+            } catch (Exception e) {
+                sink.success(false);
+            }
+        });
+    }
+}
+

spring-5-webflux-2/src/main/java/com/baeldung/webflux/zipwhen/service/EmailService.java

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+package com.baeldung.webflux.zipwhen.service;
+
+import reactor.core.publisher.Mono;
+
+public class EmailService {
+    private final UserService userService;
+
+    public EmailService(UserService userService) {
+        this.userService = userService;
+    }
+
+    public Mono<Boolean> sendEmail(String userId) {
+        return userService.getUser(userId)
+          .flatMap(user -> {
+              System.out.println("Sending email to: " + user.getEmail());
+              return Mono.just(true);
+          })
+          .defaultIfEmpty(false);
+    }
+}

spring-5-webflux-2/src/main/java/com/baeldung/webflux/zipwhen/service/UserService.java

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+package com.baeldung.webflux.zipwhen.service;
+
+import com.baeldung.webflux.zipwhen.model.User;
+
+import reactor.core.publisher.Mono;
+
+public class UserService {
+    public Mono<User> getUser(String userId) {
+        return Mono.just(new User(userId, "john Major"));
+    }
+}
+

spring-5-webflux-2/src/main/java/com/baeldung/webflux/zipwhen/web/UserController.java

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+package com.baeldung.webflux.zipwhen.web;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+
+import com.baeldung.webflux.zipwhen.model.User;
+import com.baeldung.webflux.zipwhen.service.DatabaseService;
+import com.baeldung.webflux.zipwhen.service.EmailService;
+import com.baeldung.webflux.zipwhen.service.UserService;
+
+import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Schedulers;
+import reactor.util.function.Tuples;
+
+public class UserController {
+    private final UserService userService;
+    private final EmailService emailService;
+    private final DatabaseService databaseService;
+
+    public UserController(UserService userService, EmailService emailService, DatabaseService databaseService) {
+        this.userService = userService;
+        this.emailService = emailService;
+        this.databaseService = databaseService;
+    }
+
+    @GetMapping("/example/{userId}")
+    public Mono<ResponseEntity<String>> combineAllDataFor(@PathVariable String userId) {
+        Mono<User> userMono = userService.getUser(userId);
+        Mono<Boolean> emailSentMono = emailService.sendEmail(userId)
+          .subscribeOn(Schedulers.parallel());
+        Mono<String> databaseResultMono = userMono.flatMap(user -> databaseService.saveUserData(user)
+          .map(Object::toString));
+
+        return userMono.zipWhen(user -> emailSentMono, Tuples::of)
+          .zipWhen(tuple -> databaseResultMono, (tuple, databaseResult) -> {
+              User user = tuple.getT1();
+              Boolean emailSent = tuple.getT2();
+              return ResponseEntity.ok()
+                .body("Response: " + user + ", Email Sent: " + emailSent + ", Database Result: " + databaseResult);
+          });
+    }
+}

spring-5-webflux-2/src/test/java/com/baeldung/webflux/zipwhen/UserControllerUnitTest.java

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+package com.baeldung.webflux.zipwhen;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+
+import com.baeldung.webflux.zipwhen.model.User;
+import com.baeldung.webflux.zipwhen.service.DatabaseService;
+import com.baeldung.webflux.zipwhen.service.EmailService;
+import com.baeldung.webflux.zipwhen.service.UserService;
+import com.baeldung.webflux.zipwhen.web.UserController;
+
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+public class UserControllerUnitTest {
+    @Test
+    public void givenUserId_whenCombineAllData_thenReturnsMonoWithCombinedData() {
+        UserService userService = Mockito.mock(UserService.class);
+        EmailService emailService = Mockito.mock(EmailService.class);
+        DatabaseService databaseService = Mockito.mock(DatabaseService.class);
+
+        String userId = "123";
+        User user = new User(userId, "John Doe");
+
+        Mockito.when(userService.getUser(userId))
+          .thenReturn(Mono.just(user));
+        Mockito.when(emailService.sendEmail(userId))
+          .thenReturn(Mono.just(true));
+        Mockito.when(databaseService.saveUserData(user))
+          .thenReturn(Mono.just(true));
+
+        UserController userController = new UserController(userService, emailService, databaseService);
+
+        Mono<ResponseEntity<String>> responseMono = userController.combineAllDataFor(userId);
+
+        StepVerifier.create(responseMono)
+          .expectNextMatches(responseEntity -> responseEntity.getStatusCode() == HttpStatus.OK && responseEntity.getBody()
+            .equals("Response: " + user + ", Email Sent: true, Database Result: " + true))
+          .verifyComplete();
+    }
+}