Spring Data Reactive R2DBC 分页

Question

Spring Data Reactive 不支持 Page 作为返回类型。我正在尝试使用来自服务层的两个不同查询（一个用于获取结果列表，另一个用于获取总数）来实现这一点。

第一个查询给出的内容为Flux<Person>，第二个查询给出的计数为Mono<Integer>。

我可以将这两者结合起来并返回一个Mono<Page<Person>>吗？怎么样？

请帮忙。

Answer 1

所以最后我编码如下。

我对整个反应式范式很陌生。所以下面的代码可能不是最好的方法。最终，我希望 Spring Data R2DBC 增加对 Page 返回类型的支持。上述问题的答案在 CustomMentorRepositoryImpl 类中的 search 方法实现中。

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.data.annotation.Id;
import org.springframework.data.annotation.Version;
import org.springframework.data.relational.core.mapping.Column;
import org.springframework.data.relational.core.mapping.Table;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Table("mentors")
public class Mentor {

    @Id
    private Long id;
    boolean hasId() {
        return id != null;
    }

    @Version
    @Column("version")
    private Integer version;

    @Column("name")
    private String name;

    @Column("age")
    private Integer age;

}

存储库类

import com.sample.app.domain.Mentor;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.r2dbc.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.data.repository.reactive.ReactiveCrudRepository;
import org.springframework.stereotype.Repository;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

@Repository
public interface MentorRepository extends 
    ReactiveCrudRepository<Mentor, String>, CustomMentorRepository {    
}

// CustomRepository 类

import com.sample.app.domain.Mentor;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.query.Param;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

public interface CustomMentorRepository {
    public Mono<Page<Mentor>> search(String name, Pageable page);
}

// CustomRepositoryImpl 类

import lombok.AllArgsConstructor;
import com.sample.app.domain.Mentor;
import com.sample.app.repository.CustomMentorRepository;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;
import org.springframework.data.r2dbc.core.DatabaseClient;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

@AllArgsConstructor
public class CustomMentorRepositoryImpl implements CustomMentorRepository {

    DatabaseClient databaseClient;

    @Override
    public Mono<Page<Mentor>> search(String name, Pageable page) {
        // Get the contents
        Flux<Mentor> contents = databaseClient.execute("SELECT * FROM mentors where name like :name limit :limit offset :offset")
                .bind("name", "%" + name + "%")
                .bind("limit", page.getPageSize())
                .bind("offset", page.getOffset())
                .as(Mentor.class)
                .fetch().all();
        // Get the count
        Mono<Long> count = databaseClient.execute("SELECT count(*) FROM mentors where name like :name")
                .bind("name", "%" + name + "%")
                .as(Long.class)
                .fetch().first();
        return contents.collectList().zipWith(count).flatMap(objects ->
                Mono.just(new PageImpl<Mentor>(objects.getT1(), page, objects.getT2()))
        );
    }
}