如何进行依赖的WebClient调用

Question

我需要进行3个相关的WebClient API调用。最后，我想要一个最终响应对象的Mono。我需要使用第一个API响应中的值来调用第二个API（它将返回Purchase类的Mono）。Purchase类将包含2个成员变量

1. 用户对象
2. 现在，对于列表中的每个值，我需要进行第三次API调用。然后将最终的mono对象返回到控制器

目前，我一直在研究如何为列表中的每个值（由第二个API返回）异步调用第三个API

service.get购买返回Mono

class Purchase{
   private List<Item> purchasedItemsList;
}

class Item {
   private int itemId;
   private int categoryId;
   private String itemName;
}
public Mono<FinalResponse> getEndResults(UserRequest userRequest) {
        Mono<User> response1 = service.getUserResponse(userRequest);
        return response1.flatMap(response -> {
           int userId = response.getUserId();
           FinalResponse finalResponse = new FinalResponse();
           List<AllItems> itemList = new LinkedList<>();
           return service.getPurchase(userRequest, userId)
                    .map(purchasedItem -> {
                        val.getPurchasedItemsList().forEach(oneItem -> {      // please help me how to go about from here
                              service.getSimilarItemsInCategory(userRequest, userId, oneItem.getCategoryId)
                              .map(similarItem -> { 
                                AllItems allItem = new AllItems();     
                                allItem.setPurchasedItem(oneItem);
                                allItem.setSimilarItem(similarItem);
                                itemList.add(allItem);
                              });
                        });
                finalResponse.setResults(itemList);
                 return finalResponse;
                    });
        });
    }



class FinalResponse {
    private User user;
    private List<AllItems> results;
}
class AllItems {
    private Item purchasedItem;
    private List<Item> similarItem;
}

基本上，我需要的最终响应是

{
 "users":{//UserObject//},
 "results": [
     {
         "purchasedItem": {// Purschased Item 1},
         "similarItems": [
             {//Similar Item 1},
             {//Similar Item 2}
          ]
     },
     {
         "purchasedItem": {// Purschased Item 1},
         "similarItems": [
             {//Similar Item 1},
             {//Similar Item 2}
          ]
     }
 ]

}




Answer 1

下面是Toerktumlare的评论：如果WebClient调用返回Monos或简单值或列表的流量，这可能相当简单。

您可以使用flatMapMany（）或flatMapIterable（）。

这个简化的例子怎么样？

    public Mono<FinalResponse> getEndResults(UserRequest userRequest) {
        Mono<User> userResponse = service.getUserResponse(userRequest);
        return userResponse.flatMap(response -> {
                    int userId = response.getUserId();
                    return service.getPurchase(userRequest, userId)
                            .map(Purchase::getPurchasedItemsList)
                            .flatMapIterable(purchasedItems -> purchasedItems)
                            .flatMap(oneItem -> getSimilarItemInCategory(userRequest, userId, oneItem))
                            .collectList();
                })
                .map(itemList -> {
                    FinalResponse finalResponse = new FinalResponse();
                    finalResponse.setResults(itemList);
                    return finalResponse;
                });
    }

    public Mono<AllItems> getSimilarItemInCategory(UserRequest userRequest, int userId, Item oneItem) {
        return service.getSimilarItemsInCategory(userRequest, userId, oneItem.getCategoryId())
                .map(similarItem -> {
                    AllItems allItem = new AllItems();
                    allItem.setPurchasedItem(oneItem);
                    allItem.setSimilarItem(similarItem);
                    return allItem;
                });
    }