SND - Dao 建立

NonNullApi  使用
1. 當參數傳null 時將拋出異常,除非用 @Nullable
2. 當返回值爲null 時將拋出異常，除非用  @Nullable  ，也能夠用 Optional  包裹

@NonNullApi
package org.canaan.neo4j.graph;

import org.springframework.lang.NonNullApi;

 

繼承 Neo4jRepository  接口

 

package org.canaan.neo4j.graph;

import org.canaan.neo4j.graph.entity.UserNode;
import org.springframework.data.neo4j.annotation.Depth;
import org.springframework.data.neo4j.annotation.Query;
import org.springframework.data.neo4j.repository.Neo4jRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.lang.Nullable;

import java.util.Optional;

/**
 * @author Canaan
 * @date 2019/7/11 8:47
 */
public interface UserNeo4jDao extends Neo4jRepository<UserNode, Long> {


    //@Query("MATCH (n:User{id:{0}}) RETURN n ")
    Optional<UserNode> findByUserId(Long userId);


    Optional<UserNode> findByUserId(@Param("userId") Long userId, @Depth int depth);


    @Query("MATCH p=(n:User) -->() WHERE n.userId = {0} RETURN p ")
    Optional<UserNode> findPathByUserId(Long userId);

    @Nullable
    Optional<UserNode> findByUserName(@Nullable String userName);


   @Query("MATCH (movie:Movie)-[r:RATING]\->(), (movie)<-[:ACTS_IN]-(actor:Actor) " +
           "WHERE movie.id={0} " +
           "RETURN movie as movie, COLLECT(actor) AS 'cast', AVG(r.stars) AS 'averageRating'")
    MovieData getMovieData(String movieId);

    @QueryResult
    public class MovieData {
        Movie movie;
        Double averageRating;
        Set<Actor> cast;
    }
}

查詢相差的註解能夠在  org.springframework.data.neo4j.annotation 包下找到

主要 註解 有    @Query      @Param     @Depth     @QueryResult     

 

官方文檔：

https://docs.spring.io/spring-data/neo4j/docs/5.1.3.RELEASE/reference/html/#_usage

 

接口中方法命名規則：

https://docs.spring.io/spring-data/neo4j/docs/5.1.3.RELEASE/reference/html/#_query_methods