Exclude some labels from nodes list of a path

[billxu]

Hello

I am using cypher below to find name of nodes from A to B, and attach the id of path to them.

MATCH p = (n1:A)-[*]->(n2:B)
WHERE not(exists((n2)-[]->(:B)))
UNWIND nodes(p) AS n3
RETURN n1.name, n3.name, reduce(x = '0', y IN nodes(p) | x + '_' + id(y)) AS pid

I get output as table below, in which rows(in yellow) containing null value in n3.name column are not expected to be output.

n1.name	n3.name	pid
a010	null	0_10_1_2
a010	b001	0_10_1_2
a010	b002	0_10_1_2
a010	null	0_10_1_3
a010	b001	0_10_1_3
a010	b003	0_10_1_3

How can I exclude these rows from output?

[ameyasoft · Accepted solution]

Try this:
MATCH p = (n1:A)-[*]->(n2:B)
WHERE not(exists((n2)-[]->(:B)))
UNWIND nodes(p) AS n3
with n1, n2, n3 where n3.name is not null
RETURN n1.name, n3.name, reduce(x = '0', y IN n3 | x + '_' + id(y)) AS pid

[glilienfield]

@ameyasoft‘s solution should work. Another approach is to filter the list of nodes that gets unwinded. Replace line 4 with

unwind [n in nodes(p) where n.name is not null] as n3. 

[billxu]

Thanks! This also works, too.

Thank you both!

[billxu]

Thank you! This works!