Question

I need to implement something of a ternary operator that can help me return some default values from cypher query itself.

Scenario is –

if an employee’s city is Delhi, return 5 else return 10

Something like a ternary operator.

start employee = node(5)
return employee.city == 'DELHI' ? 5 : 10 as val;

I tried things like

start employee = node(5)
return coalesce (employee.city == 'DELHI', 5)

but no luck.

Is there a way to implement such a scenario in neo4j be it Cypher or Traversal.

Answer 1

Unfortunately it is not supported out of the box but here is a hack to do it, using filter, head and collection literals.

The idea is to have a two element list and a filter expression that becomes true for the first element for your “true-branch” and alternatively true for the second element in the list whic represents the value of your false-branch.

see this console example: http://console.neo4j.org/r/6tig7g

start n=node(5) return head(filter( a in [5,10] : n.city = 'DELHI' OR a = 10))

so generally:

head(filter( a in [true-result,false-result] : CONDITION OR a = false-result))