apoc.refactor.collapseNode

Details
Syntax	`apoc.refactor.collapseNode(nodes, relType) :: (input, output, error)`
Description	Collapses the given `NODE` and replaces it with a `RELATIONSHIP` of the given type.
Input arguments	Name	Type	Description
	`nodes`	`ANY`	The nodes to collapse. Nodes can be of type `STRING` (elementId()), `INTEGER` (id()), `NODE`, or `LIST<STRING \| INTEGER \| NODE>`.
	`relType`	`STRING`	The name of the resulting relationship type.
Return arguments	Name	Type	Description
	`input`	`INTEGER`	The id of the given relationship.
	`output`	`RELATIONSHIP`	The id of the new relationship with the updated type.
	`error`	`STRING`	The message if an error occurred.

Refactoring nodes using Cypher

Node labels and relationship types can be referenced dynamically in Cypher without using APOC.

Cypher syntax for creating, matching and merging labels and types dynamically

CREATE (n1:$(label))-[r:$(type)]->(n2:$(label))
MERGE (n1:$(label))-[r:$(type)]->(n2:$(label))
MATCH (n1:$(label))-[r:$(type)]->(n2:$(label))

The dynamically calculated type must evaluate to a STRING or LIST<STRING>. For more information, see the Cypher Manual → CREATE, MERGE, MATCH.

Batching, as well as parallel execution, can be achieved in Cypher using CALL {…} IN CONCURRENT TRANSACTIONS. For more information, see CALL subqueries in transactions → Concurrent transactions.

Usage Examples

The examples in this section are based on the following sample graph:

CREATE (flight:Flight {number: "BA001"})
CREATE (origin:Airport {code: "LHR"})
CREATE (destination:Airport {code: "AMS"})
CREATE (flight)<-[:OUT]-(origin)
CREATE (flight)-[:IN]->(destination);

The following queries collapses the Flight node, replacing it with a CONNECTED to relationship in APOC and Cypher:

apoc.refactor.collapseNode

MATCH (flight:Flight {number: "BA001"})
CALL apoc.refactor.collapseNode([flight],'CONNECTED_TO')
YIELD input, output
RETURN input, output;

Using Cypher

MATCH (flight:Flight {number: "BA001"})
CALL (flight) {
    MATCH p=(a)-[]-(f)-[]-(b)
    WITH p, a, f, b LIMIT 1
    CREATE (a)-[r:CONNECTED_TO]->(b)
    SET r = properties(f)
    DETACH DELETE f
    RETURN r AS newRel
}
RETURN newRel

Results
input	output
10	[:CONNECTED_TO {number: "BA001"}]

If we execute this query, it will result in the following graph: