Mongotemplate自定义转换器不起作用答案

【问题标题】：Mongotemplate custom converter not workingMongotemplate自定义转换器不起作用
【发布时间】：2022-08-03 20:52:15
【问题描述】：

我有一个名为客户的文档列表，我使用 mongotemplate 检索了这些文档，下面是一些文档：

    {\"customer\": {\"entityPerimeter\": \"abp\", \"name\": \"ZERZER\", \"siren\": \"6154645\", \"enterpriseId\": \"546456\", \"ic01\": \"\", \"marketingOffer\": \"qlksdjf\", \"irType\": \"Router\", \"offerSpecificationOfferLabel\": \"2Mb\"}}
    {\"customer\": {\"entityPerimeter\": \"sdf\", \"name\": \"qazer\", \"siren\": \"156\", \"enterpriseId\": \"546456\", \"ic01\": \"\", \"marketingOffer\": \"qlksdjddddsqf\", \"irType\": \"Ruter\", \"offerSpecificationOfferLabel\": \"2Mb\"}}
    {\"customer\": {\"entityPerimeter\": \"zer\", \"name\": \"fazdsdfsdgg\", \"siren\": \"sdfs\", \"enterpriseId\": \"1111\", \"ic01\": \"\", \"marketingOffer\": \"qsdfqsd\", \"irType\": \"Router\", \"offerSpecificationOfferLabel\": \"2Mb\"}}

我在 mongodb 中所做的就是得到这个结果：

public List<DBObject> findAllCustomersByExtractionDateMongo(LocalDate extractionDate) {
        Aggregation aggregation = newAggregation(
                match(Criteria.where(EXTRACTION_DATE).is(extractionDate)),
                project(CUSTOMER).andExclude(\"_id\"),
                group().addToSet(\"$customer\").as(\"distinct_customers\"),
                unwind(\"distinct_customers\"),
                project().andExclude(\"_id\").and(\"distinct_customers\").as(\"customer\"),
                project().andExclude(\"distinct_customers\")

        );
        
        return template
                .aggregate(aggregation, COLLECTION, DBObject.class)
                .getMappedResults();
    }

现在我真正想要的是将这些文档映射到一个名为 Customer 的类：

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Customer {
    private String entityPerimeter;
    private String name;
    private String siren;
    private String enterpriseId;
    private String ic01;
    private String marketingOffer;
    private String product;
    private String irType;
}

我试图通过创建一个 DTO 接口来做到这一点：

public interface DocumentToCustomerMapper {
    String NULL = \"null\";
    
    static Customer getFilter(DBObject document) {
        var customer = new Customer();
        customer.setSiren(Optional.ofNullable((String) document.get(CustomerAttributes.SIREN.value())).orElse(NULL));
        customer.setEnterpriseId(Optional.ofNullable((String) document.get(CustomerAttributes.ENTERPRISE_ID.value())).orElse(NULL));
        customer.setEntityPerimeter(Optional.ofNullable((String) document.get(CustomerAttributes.ENTITY_PERIMETER.value())).orElse(NULL));
        customer.setName(Optional.ofNullable((String) document.get(CustomerAttributes.NAME.value())).orElse(NULL));
        customer.setIc01(Optional.ofNullable((String) document.get(CustomerAttributes.IC_01.value())).orElse(NULL));
        customer.setMarketingOffer(Optional.ofNullable((String) document.get(CustomerAttributes.MARKETING_OFFER.value())).orElse(NULL));
        customer.setProduct(Optional.ofNullable((String) document.get(CustomerAttributes.PRODUCT.value())).orElse(NULL));
        customer.setIrType(Optional.ofNullable((String) document.get(CustomerAttributes.IR_TYPE.value())).orElse(NULL));
        return customer;
    }
}

然后在findAllCystomersByExtractionDateMongo() 我正在这样做：

public List<Customer> findAllCustomersByExtractionDateMongo(LocalDate extractionDate) {
    Aggregation aggregation = newAggregation(
            match(Criteria.where(EXTRACTION_DATE).is(extractionDate)),
            project(CUSTOMER).andExclude(\"_id\"),
            group().addToSet(\"$customer\").as(\"distinct_customers\"),
            unwind(\"distinct_customers\"),
            project().andExclude(\"_id\").and(\"distinct_customers\").as(\"customer\"),
            project().andExclude(\"distinct_customers\")

    );

    final Converter<DBObject, Customer> converter = DocumentToCustomerMapper::getFilter;
    MongoCustomConversions cc = new MongoCustomConversions(List.of(converter));
    ((MappingMongoConverter) template.getConverter()).setCustomConversions(cc);


    return template
            .aggregate(aggregation, COLLECTION, Customer.class)
            .getMappedResults();
}

但不幸的是，它给了我一个例外：

Couldn\'t resolve type arguments for class com.obs.dqsc.api.repository.mongo_template.CustomerRepositoryImpl$$Lambda$1333/0x00000008012869a8!

我试图删除此代码：

 final Converter<DBObject, Customer> converter = DocumentToCustomerMapper::getFilter;
 MongoCustomConversions cc = new MongoCustomConversions(List.of(converter));
 ((MappingMongoConverter) template.getConverter()).setCustomConversions(cc);

然后我得到的只是客户对象中的一些空值：

Customer(entityPerimeter=null, name=null, siren=null, enterpriseId=null, ic01=null, marketingOffer=null, product=null, irType=null)
Customer(entityPerimeter=null, name=null, siren=null, enterpriseId=null, ic01=null, marketingOffer=null, product=null, irType=null)
Customer(entityPerimeter=null, name=null, siren=null, enterpriseId=null, ic01=null, marketingOffer=null, product=null, irType=null)

注意：对于性能问题，我不想在 java 端做任何映射，也不想在我的 mongo 配置中使用全局转换器。

标签： java mongodb spring-boot mapping mongotemplate

【解决方案1】：

问题是您正在使用 lambda 来表达您的转换器：

    final Converter<DBObject, Customer> converter = DocumentToCustomerMapper::getFilter;

尝试将该 sn-p 重写为其他内容（例如匿名内部类）。

这里报告了一个非常相似的问题：https://github.com/arangodb/spring-data/issues/120

【讨论】：