使用动态节点标签运行Cypher Query时出现语法错误

问题描述

你好，我正在尝试通过动态Cypher查询获取数据.但是却遇到了如下异常:

Hello i'm trying to get data by a dynamic Cypher query.. However got an exception like:

org.neo4j.rest.graphdb.query.CypherTransactionExecutionException: Error executing cypher statements [{code=Neo.ClientError.Statement.InvalidSyntax, message=Invalid input '{': expected whitespace or a label name (line 1, column 54)
"MATCH (parentNode:ParentEntity)-[:HAS_A]->(childNode:{dynamicChildEntityType})= WHERE id(parentNode)={parentNodeId}  RETURN childNode order by childNode.orderNr"
                                                      ^}]

在尝试调用方法时:

@Override
public List<ChildEntity> getChildrenOf(Long parentNodeId, String dynamicChildEntityType) {
    Map<String, Object> params = new HashMap<String, Object>();
    params.put("dynamicChildEntityType", dynamicChildEntityType);
    params.put("parentNodeId", parentNodeId);


    String cql = "MATCH (parentNode:ParentEntity)-[:HAS_A]->(childNode:{dynamicChildEntityType})= WHERE id(parentNode)={parentNodeId}  RETURN childNode order by childNode.orderNr";


    return parentRepository.query(cql, params).as(List.class);

}

您看到什么地方了吗?标签不能使用参数吗?如果是这样，您有什么建议?

can you see what is wrong?Can't i use parameters for labels? If so, what do you suggest?

提前谢谢.

注意:我在Rest Api上使用Neo4j v2.1.6.

Note: i'm using Neo4j v2.1.6 over Rest Api.

推荐答案

您不能在Cypher中使用参数化标签.这样做的理由是，不同的标签可能会导致一个完整的单独的查询计划.想想带有索引的标签，其他没有索引的标签，等等.Cypher会为参数化的Cypher字符串缓存查询计划，因此无法将标签作为参数.

You cannot use parameterized labels in Cypher. The rationale for this is that a different label might result in a complete separate query plan. Think of labels having an index, other without indexes, etc. Cypher caches the query plan for a parameterized Cypher string, therefore it's not possible to have labels as parameters.

对于标签和关系类型，您需要在客户端使用字符串连接.

For labels and relationship types you need to use string concatenation on the client side.

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