Neo4j/Cypher Create nodes from multiple nested json

Question

I am trying to create graph from the sample data below. I am new to cypher and learned new things from tutorial and stack help. I am stuck at the problem below. I am trying to create nodes from nested arrays for multiple properties.

Following the link: UNWIND multiple unrelated arrays loaded from JSON file

Sample Data:

[   {   'organization': ['MIT','Univ. of CT'],
        'student_names': ['Adam Smith'],
        'unique_id': 'ABC123'},
    {   'organization': ['Harvard'],
        'student_names': ['Adam Smith', 'Cate Scott'],
        'unique_id': 'ABC124'},
    {   'organization': ['Harvard'],
        'student_names': ['Mandy T.', 'Bob Smith'],
        'unique_id': 'ABC125'}]

Here is what I tried:

CALL apoc.load.json('file:///test2.json') YIELD value AS class
MERGE (c:Class {name: class.name})
SET
c.organization = class.organization,
c.student_names = class.student_names

WITH c, class
UNWIND class.organization AS org
MERGE (o:Organization {name: org})
MERGE (o)-[:ACCEPTED]->(c)

WITH c, class
UNWIND class.student_names AS student
MERGE (s:StudentName {name: student})
MERGE (s)-[:ATTENDS]->(o)

I keep getting error Neo.ClientError.Statement.SemanticError: Cannot merge node using null property value for name. I don't see any null values in the data. What is causing this? How can I fix this? Thanks!!!

score 1 · Accepted Answer · answered Aug 07 '19 at 13:33

MERGE doesn't work if the property on which you merging has a null value.

Here, with MERGE (c:Class {name: class.name}) You are trying merge Class node on the property name but there is no such a property in the json.

I guess you wanted to merge this on unique_id property. So you can change your as

MERGE (c:Class {unique_id: class.unique_id})

Rest of the query looks ok.

Neo4j/Cypher Create nodes from multiple nested json

1 Answers1