post route completed

src/main/java/com/nisum/ascend/promotions/controller/PromotionsController.java

 package com.nisum.ascend.promotions.controller;
 
 import com.nisum.ascend.promotions.dto.PromotionDto;
+import com.nisum.ascend.promotions.exception.PromotionAlreadyExistsException;
 import com.nisum.ascend.promotions.model.Promotion;
 import com.nisum.ascend.promotions.repository.PromotionRepository;
 import com.nisum.ascend.promotions.service.PromotionService;
@@ -33,10 +34,9 @@ public class PromotionsController {
         return null;
     }
 
-    @PostMapping()
-    public Mono<ResponseEntity<PromotionDto>> createPromotion(@RequestBody Promotion newPromotion){
-        //TODO: create promotion
-        return null;
+    @PostMapping("")
+    public Mono<PromotionDto> createPromotion(@RequestBody Promotion newPromotion){
+        return promotionService.createPromotion(newPromotion).onErrorMap(throwable -> new PromotionAlreadyExistsException());
     }
 
     @PostMapping("/bulkSearch")

src/main/java/com/nisum/ascend/promotions/exception/PromotionAlreadyExistsException.java

+package com.nisum.ascend.promotions.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.NOT_ACCEPTABLE)
+public class PromotionAlreadyExistsException extends RuntimeException{
+    public PromotionAlreadyExistsException(){
+        super("promotion already existed");
+    }
+}

src/main/java/com/nisum/ascend/promotions/exception/RestWebExceptionHandler.java

+package com.nisum.ascend.promotions.exception;
+
+import org.springframework.core.annotation.Order;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Component;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.WebExceptionHandler;
+import reactor.core.publisher.Mono;
+
+@Component
+@Order(-2)
+ class RestWebExceptionHandler implements WebExceptionHandler {
+    @Override
+    public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) {
+        if (ex instanceof PromotionAlreadyExistsException) {
+            exchange.getResponse().setStatusCode(HttpStatus.NOT_ACCEPTABLE);
+
+            return exchange.getResponse().setComplete();
+        }
+        return Mono.error(ex);
+    }
+
+}

src/main/java/com/nisum/ascend/promotions/service/PromotionService.java

 package com.nisum.ascend.promotions.service;
 
 import com.nisum.ascend.promotions.dto.PromotionDto;
+import com.nisum.ascend.promotions.model.Promotion;
 import com.nisum.ascend.promotions.repository.PromotionRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 @Service
 public class PromotionService {
@@ -19,4 +21,8 @@ public class PromotionService {
     public Flux<PromotionDto> findPromotionsByProductSku(String sku){
         return promotionRepository.findByProductSku(sku).map(PromotionDto::generateDtoFromPromotion);
     }
+
+    public Mono<PromotionDto> createPromotion(Promotion promotion){
+        return promotionRepository.save(promotion).map(PromotionDto::generateDtoFromPromotion);
+    }
 }

src/test/java/com/nisum/ascend/promotions/controller/PromotionsControllerTest.java

@@ -14,6 +14,7 @@ import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 import org.springframework.test.web.reactive.server.WebTestClient;
+import reactor.core.publisher.Mono;
 
 import java.util.List;
 
@@ -48,4 +49,16 @@ class PromotionsControllerTest {
                     });
                 });
     }
+
+    @Test
+    void createPromotion(){
+        Promotion promotion = new Promotion("50OFF","SH1234", (float) 0.5,5);
+        webTestClient.post().uri("/api/promos")
+                .contentType(MediaType.valueOf(MediaType.APPLICATION_JSON_VALUE))
+                .body(Mono.just(promotion),Promotion.class)
+                .exchange()
+                .expectStatus().isOk()
+                .expectBody()
+                .jsonPath("$.promotionId","50OFF");
+    }
 }
\ No newline at end of file