CODEWITHSUNDEEP
neo4jcypherpy2neo
Rajendra Kadam
Rajendra Kadam

Reputation: 4052

How to Copy Sub-Graph in Neo4j using Cypher

I am trying to simulate a file system using Neo4j, Cypher, and Python(Py2Neo).

I have created the data model as shown in the following screenshot.

Type=0 means folder and type=1 means file.

. enter image description here .

I am implementing functions like Copy, Move etc for files/folders.

Move functions look simple, I can create a new relationship and delete the old one. But copying files/folders need to copy the sub-graph.

How can I copy the sub-graph?

I am creating a python module so trying to avoid apoc.

Upvotes: 4

Views: 1527

Answers (1)

InverseFalcon
InverseFalcon

Reputation: 30397

Even though you're trying to avoid APOC, it already has this feature implemented in the most recent release: apoc.refactor.cloneSubgraph()

For a non-APOC approach you'll need to accomplish the following:

  1. MATCH to distinct nodes and relationships that make up the subgraph you want to clone. Having a separate list for each will make this easier to process.

  2. Clone the nodes, and get a way to map from the original node to the cloned node.

  3. Process the relationships, finding the start and end nodes, and following the mapping to the cloned nodes, then create the same relationship type using the cloned nodes for your start and end nodes of the relationship, then copy properties from the original relationship. This way you don't have any relationships to the originals, just the clones.

  4. Determine which nodes you want to reanchor (you probably don't want to clone the original), and for any relationship that goes to/from this node, create it (via step 3) to the node you want to use as the new anchor (for example, the new :File which should be the parent of the cloned directory tree).

All this is tough to do in Cypher (steps 3 and 4 in particular), thus the reason all this was encapsulated in apoc.refactor.cloneSubgraph().

Upvotes: 5

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