Delete relationship between neo4j nodes using relationship_id, in neomodel

Question

I have neo4j node and relationship schema in neomodel as given below. Now I need to create a function so that it takes the uid of the PersonRel and delete the relationship between the two persons connected by this relationship. I couldn't find it in the documentation: https://neomodel.readthedocs.io/en/latest/

class PersonRel(StructuredRel):
    uid = StringProperty()
    created_at = DateTimeProperty(
        default=lambda: datetime.now(pytz.utc)
    )
    weight = FloatProperty()
    direction = StringProperty()


class PersonNode(StructuredNode):
    uid = UniqueIdProperty()
    label = StringProperty(required=True)
    description = StringProperty()
    related_to = RelationshipFrom("PersonNode", "related_to", model=PersonRel)
    created_at = DateTimeProperty(
        default=lambda: datetime.now(pytz.utc)
    )

Rajendra Kadam · Answer 1 · 2019-07-22T10:08:30.590

2

I use Py2Neo so, I am not familiar with the Neomodel. If you don't find any option to find and delete relationship by the property, you can choose to delete it with the standalone Cypher query.

You can execute the standalone cypher query in Neomodel like:

db.cypher_query(query, params)

Your delete query would be like:

MATCH ()-[rel]-() WHERE rel.uid={{uid}} DELETE rel

edited Jul 22 '19 at 10:08

answered Jul 22 '19 at 06:30

Rajendra Kadam

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Thanks for the answer, it helped a lot. But I had to make a few changes, as the query didn't run as it is. So, I am posting the answer separately, so that is it a bit more clear. – Kshitij Mittal Jul 22 '19 at 10:04

score 1 · Accepted Answer · answered Jul 22 '19 at 10:10

As Raj pointed out, it is possible in Neomodel to write any raw cypher query as well. However, in the documentation, the process is not clearly described.

The following code finally helped me to get the required results:

from neomodel import db as neodb
neodb.cypher_query("MATCH ()-[rel {uid:{uid}}]-() delete rel", {"uid": rel_id})

To be noted, the params are required to be passed as a dictionary, which is not mentioned in the documentation. Also, {uid:{uid}} - in this part of the query, the inner uid, which is again is curly braces, is a variable which should be passed in params. But the outer braces are a part of cypher syntax, so neomodel code doesn't consider that as a variable. Also, there is no need to add quotes around {uid}.

Delete relationship between neo4j nodes using relationship_id, in neomodel

2 Answers2