Creating nodes and relationships in Neo4j in the same query from JSON file

Question

Suppose I have a JSON file like this:

{
    data: [
        {
            name: "1",
            description: "Node 1",
            parent: ""
        },
        {
            name: "2",
            description: "Node 2",
            parent: "1"
        },
        {
            name: "3",
            description: "Node 3",
            parent: "1"
        },
        {
            name: "4",
            description: "Node 4",
            parent: "3"
        },
    ]
}

I wish to create the nodes and the relationships in the same query using neo4j-driver for Node.js. Suppose I have that JSON file loaded in a variable called data. I've tried this, but haven't been able to create the relationships:

const result = await session.run(`
    UNWIND $nodes AS node
    MERGE (n:Node { name: node.name, description: node.description })
    WITH $nodes AS relationships
    UNWIND relationships AS relationship
    MATCH(c:Node { name: relationship.name }), (p:Node { name: relationship.parent })
    MERGE (p)-[:PARENT_OF]->(n)
`, { nodes: data });

I get two relationships from 1 to a null node and from 2 to a null node.

Is there any way to do this or should I first create the nodes and then in another query create the relationships.

Thank you

Graphileon · Accepted Answer · 2020-06-28 07:22:48Z

1

You can do it in a single run:

UNWIND $nodes AS node
MERGE (n:Node { name: node.name })
ON CREATE SET n.description = node.description
FOREACH ( i IN (CASE WHEN node.parent<>'' THEN [1] ELSE [] END) |
     MERGE (p:Node { name: node.parent }) 
     MERGE (p)-[:PARENT_OF]->(n)
)

edited Jun 28, 2020 at 7:22

answered Jun 28, 2020 at 4:37

Graphileon

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