Neo4j load data relations with unknown labels - neo4j

Question

I have 4 Labels (A, B, C, D). All of them have a single Property {id}.
Now I have a file with relations which I would like to load. Every row has this structure:
{id_1}, {type_of_relations}, {id_2}
How can I create the relations?
My non-working guess is:
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM "file:/data.csv" AS line
FIELDTERMINATOR ','
MATCH (a:A{id:line.id_1} OR a:B{id:line.id_1} OR a:C{id:line.id_1} OR a:D{id:line.id_1})
MATCH (b:A{id:line.id_2} OR b:B{id:line.id_2} OR b:C{id:line.id_2} OR b:D{id:line.id_2})
MERGE (a)-[:line.type_of_relations]->(b)

Answer 1

You cannot parameterize the relationship type in Cypher.
However, you can do this using the apoc.create.relationship procedure in Neo4j apoc procedures:
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM "file:///file.csv" AS row
MATCH (a) WHERE a.id = row.id_1
MATCH (b) WHERE b.id = row.id_2
CALL apoc.create.relationship(a, row.type_of_relations, {}, b) YIELD rel
RETURN count(*) AS num
The procedure takes a parameter for the relationship type which allows for creating dynamic relationship types.

Answer 2

I don't think you can do that. For a number of reasons.
create (f:bar {name:'NewUserA'})
create (f:foo {name:'NewUserA'})
match (f:foo {name:'NewUserA'} or f:bar {name:'NewUserA'}) return f;
Code
Invalid input 'o': expected whitespace, comment, ')' or a relationship pattern (line 1, column 32 (offset: 31))
"match (f:foo {name:'NewUserA'} or f:bar {name:'NewUserA'}) return f".
So there is a problem on the match at any rate.
If the id is globally unique then you can ignore the label and just match on the id. that will take care of your 'or' problem.
match (f) where f.name='NewUserA' match (t) where t.name='NewUserA' return f,t
would give you the nodes.
That being said, when coding parameterized queries RELATIONSHIP_TYPE is one of the items you cannot parameterize. From the docs:
5.5. Parameters
[..]
Parameters can not be used as for property names, relationship types and labels, since these patterns are part of the query structure that is compiled into a query plan.
[..]
So you may need to look to ways of building your MERGE as a string somewhere else (awk is your friend) and then running that in the shell.