Predicates are boolean functions that return true or false for a given set of input.
They are most commonly used to filter out subgraphs in the WHERE part of a query.
See also Section 8.4.2, “Comparison operators”.
Tests whether a predicate holds for all element of this collection collection.
Syntax: ALL(identifier in collection WHERE predicate)
Arguments:
- collection: An expression that returns a collection
- identifier: This is the identifier that can be used from the predicate.
- predicate: A predicate that is tested against all items in the collection.
Query.
MATCH p=(a)-[*1..3]->(b) WHERE a.name='Alice' AND b.name='Daniel' AND ALL (x IN nodes(p) WHERE x.age > 30) RETURN p
All nodes in the returned paths will have an age property of at least 30.
Result
| p |
|---|
| 1 row |
|
Tests whether a predicate holds for at least one element in the collection.
Syntax: ANY(identifier in collection WHERE predicate)
Arguments:
- collection: An expression that returns a collection
- identifier: This is the identifier that can be used from the predicate.
- predicate: A predicate that is tested against all items in the collection.
Query.
MATCH (a) WHERE a.name='Eskil' AND ANY (x IN a.array WHERE x = "one") RETURN a
All nodes in the returned paths has at least one one value set in the array property named array.
Returns true if the predicate holds for no element in the collection.
Syntax: NONE(identifier in collection WHERE predicate)
Arguments:
- collection: An expression that returns a collection
- identifier: This is the identifier that can be used from the predicate.
- predicate: A predicate that is tested against all items in the collection.
Query.
MATCH p=(n)-[*1..3]->(b) WHERE n.name='Alice' AND NONE (x IN nodes(p) WHERE x.age = 25) RETURN p
No nodes in the returned paths has a age property set to 25.
Result
| p |
|---|
| 2 rows |
|
|
Returns true if the predicate holds for exactly one of the elements in the collection.
Syntax: SINGLE(identifier in collection WHERE predicate)
Arguments:
- collection: An expression that returns a collection
- identifier: This is the identifier that can be used from the predicate.
- predicate: A predicate that is tested against all items in the collection.
Query.
MATCH p=(n)-->(b) WHERE n.name='Alice' AND SINGLE (var IN nodes(p) WHERE var.eyes = "blue") RETURN p
Exactly one node in every returned path will have the eyes property set to "blue".
Result
| p |
|---|
| 1 row |
|