How do I create relationships from substrings in Neo4J

Question

I have a set of 'tag' nodes and 'category' nodes, and wanted to generate relationships between the two by testing if the category's name is a substring of the tag's name. This was my approach thus far (apologies, I'm one day into cypher so this may be fundamentally flawed but I am yet to find something equivalent to reverse engineer thus far)

match(cat:category)
match(tag:tag) where tag.name =~ '.*'+cat.name+'.*'
merge (tag)-[:belongs_to]-(cat)

Error:

Type mismatch: expected Boolean, Collection<Boolean> or Collection<Collection<Boolean>> but was String (line 2, column 48 (offset: 67))
"match(tag:tag) where tag.name =~ '.*'+cat.name+'.*'"

The error seems to revolve around the use of =~ and concatenated strings, any advice would be appreciated!

Answer 1

The problem is with the order in which the expression in the WHERE clause is evaluated. You can get around it by being explicit: enclose the string concatenation in parentheses.

WHERE tag.name =~ ('.*' + cat.name + '.*')

I tried quickly looking for documentation on cypher operator precedence but it wasn't in the operator chapter , so I'm not sure where this is documented.