如何在Python的Neo4J中使用字典参数

Question

如何在Python的Neo4J中使用字典参数

3

我正在使用 py2neo 在 Python 中运行Cypher查询。目前，我正在传递 $user_id 和 $name 的值。

query = "MATCH (user:User{id:$user_id, name: $name}) MATCH (user)-[rout]->() WITH user, collect(DISTINCT {relationship: type(rout), node: endNode(rout)}) AS extended_info RETURN { user: user, extended_info: extended_info } AS result"

graph.run(query, parameters= {"user_id": 1, "name": "Vivek"}).data()

我想要传递一个键和值的字典，而不仅仅是传递值。就像这样：

{id:1, name: "Vivek"}

并直接在查询中使用它。这将使我具有编写单个查询以过滤一个或多个属性的灵活性。

query = "MATCH (user:User{$params}) MATCH (user)-[rout]->() WITH user, collect(DISTINCT {relationship: type(rout), node: endNode(rout)}) AS extended_info RETURN { user: user, extended_info: extended_info } AS result"

graph.run(query, parameters= {id:1, name: "Vivek"}).data()

是否有使用py2neo来完成此操作的方法？或者是否有其他方法可以编写仅需一次查询的匹配查询？

- Vivek Maskara

1个回答

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- stellasia · Accepted Answer

如果可以的话，一种解决方案是使用字符串格式化动态构建查询：

First try to create a query with properties.
```
query = "MATCH (u:User {{ {properties} }}) RETURN u.name"
```
{properties} will be replaced by string formating, while the {{ ... }} will be converted to single brackets {..} during string formating.
Define your paramters: warning remember that in python, dictionnary keys must be string (well, not only, but in this case yes)
```
parameters = {"id": 1, "name": "Toto"}
```

Create the properties list for py2neo:

properties = ', '.join('{0}: ${0}'.format(n) for n in parameters)

Format your query:

query2 = query.format(properties=properties)
print(query2)

query2 now look like this:

MATCH (u:User { id: $id, name: $name }) RETURN u.name

Finally, you can run query2 with parameters:

r = graph.run(query2, parameters=parameters)
print(r.data())

请注意，我们可以在那里完全格式化字符串以注入参数，但我更喜欢让py2neo在那里执行必要的检查。