使用 Py2Neo 通过合并更新节点

Question

我正在尝试使用 py2neo 库合并然后更新图形。我的代码看起来大致像

from py2neo import Graph, Node, Relationship

graph = Graph(host, auth=(user, password,))

tx = graph.begin()
alice = Node("Person", name="Alice")
bob = Node("Person", name="Bob")
KNOWS = Relationship(alice, "KNOWS", bob)
tx.create(KNOWS)
graph.commit(tx)

这会按预期创建节点和边

(:Person {name: "Alice"})-[:KNOWS]->(:Person {name: "Bob"})

如果我尝试在新交易中修改 alice，我没有得到任何改变

例如

new_tx = graph.begin()
alice["age"] = 32
new_tx.merge(alice, "Person", "name")
graph.commit(new_tx)

我怀疑我误解了 Transaction 在这里的工作原理。我希望以上内容等同于找到 Alice 并使用新属性更新或创建新节点。

更新：我发现了 Graph.push 方法，但仍希望获得有关最佳实践的建议。

Answer 1

您需要定义一个主键，让 MERGE 知道哪个属性用作主键。来自文档：

The primary property key used for Cypher MATCH and MERGE operations. If undefined, the special value of "id" is used to hinge uniqueness on the internal node ID instead of a property. Note that this alters the behaviour of operations such as Graph.create() and Graph.merge() on GraphObject instances.

为每个节点类型定义自定义 class 并在其中定义主键可能是最佳做法。

class Person(GraphObject):
    __primarykey__ = "name"

    name = Property()
    born = Property()

    acted_in = RelatedTo(Movie)
    directed = RelatedTo(Movie)
    produced = RelatedTo(Movie)

使用 Py2Neo 通过合并更新节点

Updating a node with merge using Py2Neo

python

neo4j

py2neo