16.1. Predicates

16.1.1. ALL
16.1.2. ANY
16.1.3. NONE
16.1.4. SINGLE

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 12.1.2, “Comparison operators”.

Figure 16.1. Graph


16.1.1. ALL

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

[Node[3]{name:"Alice",age:38,eyes:"brown"},:KNOWS[1]{},Node[5]{name:"Charlie",age:53,eyes:"green"},:KNOWS[3]{},Node[1]{name:"Daniel",age:54,eyes:"brown"}]


16.1.2. ANY

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.

Result

a
1 row

Node[2]{name:"Eskil",age:41,eyes:"blue",array:["one","two","three"]}


16.1.3. NONE

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

[Node[3]{name:"Alice",age:38,eyes:"brown"},:KNOWS[1]{},Node[5]{name:"Charlie",age:53,eyes:"green"}]

[Node[3]{name:"Alice",age:38,eyes:"brown"},:KNOWS[1]{},Node[5]{name:"Charlie",age:53,eyes:"green"},:KNOWS[3]{},Node[1]{name:"Daniel",age:54,eyes:"brown"}]


16.1.4. SINGLE

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

[Node[3]{name:"Alice",age:38,eyes:"brown"},:KNOWS[0]{},Node[4]{name:"Bob",age:25,eyes:"blue"}]