Spring Boot + Webflux + Reactive MongoDB - 通过属性 Id 获取文档 [英] Spring Boot + Webflux + Reactive MongoDB - get document by property Id

问题描述

我想按 Offer.ProductProperties.brand 查找所有优惠文件:

I'd like to find all Offer documents by Offer.ProductProperties.brand:

@Document(collection = "offers")
public class Offer {

    @Id
    private String id;

    @NotNull
    @DBRef
    private ProductProperties properties;

产品属性:

@Document(collection = "product_properties")
public class ProductProperties {
    @Id
    private String id;

    @NotNull
    @NotEmpty
    private String brand;

服务:

Flux<ProductProperties> all = productPropertiesRepository.findAllByBrand(brand);
        List<String> productPropIds = all.toStream()
                .map(ProductProperties::getId)
                .collect(Collectors.toList());
        Flux<Offer> byProperties = offerRepository.findAllByProperties_Id(productPropIds);

但不幸的是 byProperties 是空的.为什么?

But unfortunately byProperties is empty. Why?

我的仓库:

public interface OfferRepository extends ReactiveMongoRepository<Offer, String> {

    Flux<Offer> findAllByProperties_Id(List<String> productPropertiesIds);
}

如何按 ProductProperties.brand 查找所有优惠?

How to find all Offers by ProductProperties.brand?

谢谢！

推荐答案

阅读一些documentation 发现您无法使用 @DBRef 进行查询.因此消息

After reading some documentation found out that You cannot query with @DBRef. Hence the message

无效的路径引用属性.品牌！关联只能是直接或通过他们的 id 属性指向

Invalid path reference properties.brand! Associations can only be pointed to directly or via their id property

如果您从字段中删除 DBRef，您应该可以通过 findAllByProperties_BrandAndProperties_Capacity 进行查询.

If you remove DBRef from the field, you should be able to query by findAllByProperties_BrandAndProperties_Capacity.

所以唯一的方法就是你的表现.即获取 id 并按 id 查询.
正如我在评论中所说，它不起作用的原因是因为 findAllByProperties_Id 的返回类型是 Flux.所以除非你执行终端操作，否则你不会有任何结果.试试

So the only ways is how you are doing. i.e. Fetch id's and query by id.
As I said in the comment, the reason it is not working is because return type of findAllByProperties_Id is a Flux. So unless u execute a terminal operation, you wont have any result. Try

 byProperties.collectList().block()

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