如何在neo4j中获取特定节点的所有子节点

Question

我 在我的 neo4j 中有这种关系：

Parent -> Childs
F -> D,E
D -> A,B,C

用例：我正在尝试使用此查询

获取特定节点的所有child

MATCH (p:Person{name:"F"})<-[:REPORTS_TO*]-(c) 
RETURN {parent : p.name, child : {name :collect( c.name)}}

这个 returns 我这个 :

{"parent":"F","child":{"name":["D","A","B","C","E"]}}

A, B, C 不是 F 的直接 child，因为它们是 D

的 child

要求的回复是

[
"F" : [ Childs i.e "E", "D" ]
"E" : []
"D" : [ "A", "B", "C" ]
 and so on ....
]

实现此目的的一种方法是递归地触发以下查询：

MATCH (p:Person{name:"F"})<-[:REPORTS_TO]-(c) 
RETURN {parent : p.name, child : {name :collect( c.name)}}

哪个returns

{"parent":"F","child":{"name":["E","D"]}}

然后搜索 E and D 的所有 child，然后搜索 child 的 child，依此类推..

我的问题是我可以在单个查询中或以更好的方式实现吗？

Edit1：添加数据集

CREATE (f:Person {name: "F"})
CREATE (e:Person {name: "E"})
CREATE (d:Person {name: "D"})
CREATE (c:Person {name: "C"})
CREATE (b:Person {name: "B"})
CREATE (a:Person {name: "A"})
CREATE (x:Person {name: "X"})
CREATE (a)-[:REPORTS_TO]->(x)
CREATE (d)-[:REPORTS_TO]->(a)
CREATE (d)-[:REPORTS_TO]->(b)
CREATE (d)-[:REPORTS_TO]->(c)
CREATE (f)-[:REPORTS_TO]->(d)
CREATE (f)-[:REPORTS_TO]->(e)

Answer 1

您可以使用 OPTIONAL MATCH 来实现您的目标。

您的数据集如下所示：

试一试：

MATCH (p:Person)
OPTIONAL MATCH (p)<-[:REPORTS_TO]-(c) 
RETURN {parent : p.name, child : {name :collect( c.name)}}

查询结果：

+-----------------------------------------------------+
| {parent : p.name, child : {name :collect( c.name)}} |
+-----------------------------------------------------+
| {parent=D, child={name=[C, B, A]}}                  |
| {parent=A, child={name=[]}}                         |
| {parent=C, child={name=[]}}                         |
| {parent=F, child={name=[E, D]}}                     |
| {parent=E, child={name=[]}}                         |
| {parent=B, child={name=[]}}                         |
+-----------------------------------------------------+

如果您只需要一个特定的 parent 和您各自的 children，您可以这样做：

MATCH (p:Person)
WHERE p.name = "D"
OPTIONAL MATCH (p)<-[:REPORTS_TO]-(c) 
WITH COLLECT (c) + p AS all
UNWIND all as p
MATCH (p)
OPTIONAL MATCH (p)<-[:REPORTS_TO]-(c) 
RETURN {parent : p.name, child : {name :collect( c.name)}}

结果：

+-----------------------------------------------------+
| {parent : p.name, child : {name :collect( c.name)}} |
+-----------------------------------------------------+
| {parent=D, child={name=[C, B, A]}}                  |
| {parent=A, child={name=[]}}                         |
| {parent=C, child={name=[]}}                         |
| {parent=B, child={name=[]}}                         |
+-----------------------------------------------------+

编辑：

来自@Prakash Pandey 的评论：

how can we do something like childs, childs of childs and so on where p.name = "Tom"

根据题中添加的数据集，可以做：

MATCH (p:Person)<-[:REPORTS_TO*]-(c:Person)
WHERE p.name = "X"
WITH COLLECT (c) + p AS all UNWIND all as p
MATCH (p)<-[:REPORTS_TO]-(c)
RETURN {parent : p.name, child : {name :collect( c.name)}}

结果：

+-----------------------------------------------------+
| {parent : p.name, child : {name :collect( c.name)}} |
+-----------------------------------------------------+
| {parent=D, child={name=[F]}}                        |
| {parent=A, child={name=[D]}}                        |
| {parent=X, child={name=[A]}}                        |
+-----------------------------------------------------+

Answer 2

我创建了您描述的图表。

下面的查询returns大部分是你需要的：

MATCH (a:Parent)<-[r:isParent*0..]-(b:Parent)
return {parent:a.name,child : {name :collect( b.name)}}

结果：

{"parent":"D","child":{"name":["D","A","B","C"]}}

{"parent":"A","child":{"name":["A"]}}

{"parent":"C","child":{"name":["C"]}}

{"parent":"F","child":{"name":["F","D","E","A","B","C"]}}

{"parent":"E","child":{"name":["E"]}}

{"parent":"B","child":{"name":["B"]}}

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