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neo4jcyphergraph-databases

Cypher: How to update property if the property is an array and an aggregated count?

I have a node which has property span_id, contact and count, where span_id is a fixed string, but contacts is an array of contact_id, and count is an integer.

My question is if Cypher query can update the node by appending new elements in the array, and aggregated the count?

For example, I created a node as follows

(s:Service {span_id:"A", contacts:["A1"], count=1}

Later, I got an event which has contact_id = "B2", and span_id is still "A". Now the node needs to be updated as

(s:Service {span_id:"A", contacts:["A1", "B2"], count=2}

Later again, another event has contact_id = "C3", span_id= "A", so the node needs to be updated

(s:Service {span_id:"A", contacts:["A1", "B2", "B3"], count=3}

....

Does Cypher support the updating?

Solution

  • You can add an item to a list using the addition operator. And you can set a property based on the length of the list.

    WITH ["C3"] as mynewelement
MATCH (n {span_id:'A'})
SET n.count = size(n.contacts+mynewelement)
SET n.contact = = n.contacts + mynewelement