Looking for a way to use merge in the case of more than 2 relationships

Neo4j Graph Platform Cypher
1

I have four "generic labels":

  1. EngineCapacity
  2. HorsePower
  3. Transmission
  4. NumberOfDoors

Now I want to connect these nodes to my Car nodes.
But I don't want to connect them straight onto to it. I first connect them to a Combo node and then that is connected to the Car.

So, I first need to make sure the "generic" nodes exists, then make sure the "combo" node exists and then make sure the "combo" node is connected to the car.

I tried this

with 13900 as engineCapacity, 160 as horsePower, 'automatic' as transmission, 5 as nDoors

merge (engineNode:EngineCapacity {value:engineCapacity})
merge (hpNode:HorsePower {value:horsePower})
merge (transNode:Transmission {value:transmission})
merge (doorsNode:NumberOfDoors {value:nDoors})
merge (carNode:Car {value:'VW Golf mk6 1.4 TSI 160BHP'})

with engineNode, hpNode, transNode, doorsNode, carNode

merge (combo:Combo)<-[:IN_COMBO]-(engineNode),
(combo)<-[:IN_COMBO]-(hpNode),
(combo)<-[:IN_COMBO]-(transNode),
(combo)<-[:IN_COMBO]-(doorsNode),
(combo)-[:SPECIFIES_CAR]->(carNode)

which obviously doesn't work.

Then I tried

with 13900 as engineCapacity, 160 as horsePower, 'automatic' as transmission, 5 as nDoors

merge (engineNode:EngineCapacity {value:engineCapacity})
merge (hpNode:HorsePower {value:horsePower})
merge (transNode:Transmission {value:transmission})
merge (doorsNode:NumberOfDoors {value:nDoors})
merge (carNode:Car {value:'VW Golf mk6 1.4 TSI 160BHP'})

with engineNode, hpNode, transNode, doorsNode, carNode

match (combo:Combo)<-[:IN_COMBO]-(engineNode),
(combo)<-[:IN_COMBO]-(hpNode),
(combo)<-[:IN_COMBO]-(transNode),
(combo)<-[:IN_COMBO]-(doorsNode),

with count(combo) as counter, engineNode, hpNode, transNode, doorsNode, carNode
case counter
	when 0 then create(combo2:Combo)<-[:IN_COMBO]-(engineNode),
        (combo2)<-[:IN_COMBO]-(hpNode),
        (combo2)<-[:IN_COMBO]-(transNode),
        (combo2)<-[:IN_COMBO]-(doorsNode)
end
merge (combo2)-[:SPECIFIES_CAR]->(carNode)

which again doesn't work.

Any ideas how to handle this?
Thanks

2

Thanks for providing good amount of details in your question. But it'd be more helpful if you could provide the errors you're getting in both the ways.
Btw, for now I solved it by merging each relation separately.

with 13900 as engineCapacity, 160 as horsePower, 'automatic' as transmission, 5 as nDoors

merge (engineNode:EngineCapacity {value:engineCapacity})
merge (hpNode:HorsePower {value:horsePower})
merge (transNode:Transmission {value:transmission})
merge (doorsNode:NumberOfDoors {value:nDoors})
merge (carNode:Car {value:'VW Golf mk6 1.4 TSI 160BHP'})

with engineNode, hpNode, transNode, doorsNode, carNode

merge (combo:Combo)<-[:IN_COMBO]-(engineNode)
merge (combo)<-[:IN_COMBO]-(hpNode)
merge (combo)<-[:IN_COMBO]-(transNode)
merge (combo)<-[:IN_COMBO]-(doorsNode)
merge (combo)-[:SPECIFIES_CAR]->(carNode)

Hope it helps :slight_smile:

3

Wow it works :stuck_out_tongue:
I can't believe it was that simple as it took me a couple of hours and I gave up.
It's just a concept to begin with which I'm not sure I'm going to use.

Thanks!

4

Glad I could help :)