如何使用neo4jclient解开两个列表？

Question

我有一个方法可以传递现有节点的标题和两个列表。一个包含新节点的标题，另一个包含应作为属性添加到新关系的计数。两个列表都包含相同数量的项目。

我展开新文章列表，并可以使用以下代码成功添加新节点：

public async Task AddArticlesWithRelationshipsAsync(List<string> newArticleTitles, string linkedFromArticle, List<int> count)
{
    await client
        .Cypher
        .Unwind(newArticleTitles, "newArticleTitle")
        .Match("(linkedFromArticle:Article)")
        .Where("linkedFromArticle.title = { linkedFromArticle}")
        .WithParam("linkedFromArticle", linkedFromArticle)
        .Merge("(newArticle: Article { title: newArticleTitle } )")
        .Merge("(newArticle)< -[:REFERENCES { count: 500 }]-(linkedFromArticle)")
        .ExecuteWithoutResultsAsync();
}

但是，硬编码为500.我正在努力利用<int>的计数。到目前为止，我最好的尝试是展开count列表：

public async Task AddArticlesWithRelationshipsAsync(List<string> newArticleTitles, string linkedFromArticle, List<int> count)
{
    await client
        .Cypher
        .Unwind(newArticleTitles, "newArticleTitle")
        .Unwind(count, "count")
        .Match("(linkedFromArticle:Article)")
        .Where("linkedFromArticle.title = { linkedFromArticle}")
        .WithParam("linkedFromArticle", linkedFromArticle)
        .Merge("(newArticle: Article { title: newArticleTitle } )")
        .Merge("(newArticle)< -[:REFERENCES { count: count }]-(linkedFromArticle)")
        .ExecuteWithoutResultsAsync();
}

不幸的是，这会增加所有新节点与所有关系计数之间的关系。如何将两个列表与具有相同索引的项配对？

Answer 1

我写了一个Cypher查询，使用range()函数和FOREACH来解决问题。

首先，我创建了一个:Article节点：

CREATE (:Article {title : 'Article A'})

之后，我将Neo4j浏览器参数配置为：

:params { linkedFromArticle : 'Article A', newArticleTitles : ['Article B', 'Article C', 'Article D'], count : [10, 20, 30] }

然后，Cypher查询：

MATCH (linkedFromArticle:Article)
WHERE linkedFromArticle.title = {linkedFromArticle}
WITH linkedFromArticle, RANGE(0, SIZE({count}) - 1) AS indexes
FOREACH(index IN indexes |
    MERGE (newArticle:Article { title: {newArticleTitles}[index] } )
    MERGE (newArticle)-[:REFERENCES {count : {count}[index]}]->(linkedFromArticle)
)

结果图：

修改

使用Neo4jClient的等效C＃函数：

public async Task AddArticlesWithRelationshipsAsync(List<string> newArticleTitles, string linkedFromArticle, List<int> count) {
    await client
    .Cypher
    .WithParam("newArticleTitles", newArticleTitles)
    .WithParam("linkedFromArticle", linkedFromArticle)
    .WithParam("count", count)
    .Match("(linkedFromArticle:Article)")
    .Where("linkedFromArticle.title = {linkedFromArticle}")
    .With("linkedFromArticle, RANGE(0, SIZE({count}) - 1) AS indexes")
    .ForEach("(index IN indexes | " +
             "MERGE (newArticle:Article { title: {newArticleTitles}[index] } )" +
             "MERGE (newArticle)-[:REFERENCES {count : {count}[index]}]->(linkedFromArticle)" +
     ")")
    .ExecuteWithoutResultsAsync();
}