Recursive relationship functions

Function	Description
`NODES`	returns all nodes from a recursive relationship
`RELS`	returns all rels from a recursive relationship
`PROPERTIES`	return given property from nodes/relationships
`IS_TRAIL`	check if path contains repeated relationships
`IS_ACYCLIC`	check if path contains repeated nodes
`LENGTH`	returns the number of relationships (path length) in a recursive relationship

NODES

Returns all nodes from path.

Input type	Output type
`RECURSIVE_REL`	`LIST[NODE]`

MATCH p = (a:User)-[:Follows*1..2]->(:User)
WHERE a.name = 'Adam'
RETURN nodes(p);

Output:

------------------------------------------------------------------------------------
| NODES(p)                                                                         |
------------------------------------------------------------------------------------
| [{_ID: 0:0, _LABEL: User, name: Adam, age: 30},{_ID: 0:1, _LABEL: User, name:... |
------------------------------------------------------------------------------------
| [{_ID: 0:0, _LABEL: User, name: Adam, age: 30},{_ID: 0:1, _LABEL: User, name:... |
------------------------------------------------------------------------------------
| [{_ID: 0:0, _LABEL: User, name: Adam, age: 30},{_ID: 0:2, _LABEL: User, name:... |
------------------------------------------------------------------------------------
| [{_ID: 0:0, _LABEL: User, name: Adam, age: 30},{_ID: 0:2, _LABEL: User, name:... |
------------------------------------------------------------------------------------

RELS

Returns all relationships from a recursive relationship.

Input type	Output type
`RECURSIVE_REL`	`LIST[REL]`

MATCH p = (a:User)-[:Follows*1..2]->(:User)
WHERE a.name = 'Adam'
RETURN rels(p);

Output:

------------------------------------------------------------------------------------
| RELS(p)                                                                          |
------------------------------------------------------------------------------------
| [(0:0)-{_LABEL: Follows, _ID: 2:0, since: 2020}->(0:1)]                          |
------------------------------------------------------------------------------------
| [(0:0)-{_LABEL: Follows, _ID: 2:0, since: 2020}->(0:1),(0:1)-{_LABEL: Follows... |
------------------------------------------------------------------------------------
| [(0:0)-{_LABEL: Follows, _ID: 2:1, since: 2020}->(0:2)]                          |
------------------------------------------------------------------------------------
| [(0:0)-{_LABEL: Follows, _ID: 2:1, since: 2020}->(0:2),(0:2)-{_LABEL: Follows... |
------------------------------------------------------------------------------------

PROPERTIES

Return given property from nodes/relationships.

Input type	Output type
`LIST[NODE/REL]`, `STRING`	`LIST[ANY]`

MATCH p = (a:User)-[:Follows*1..2]->(:User)
WHERE a.name = 'Adam'
RETURN properties(nodes(p), 'name') AS name, properties(rels(p), 'since') AS since;

Output:

--------------------------------------
| name                 | since       |
--------------------------------------
| [Adam,Karissa]       | [2020]      |
--------------------------------------
| [Adam,Karissa,Zhang] | [2020,2021] |
--------------------------------------
| [Adam,Zhang]         | [2020]      |
--------------------------------------
| [Adam,Zhang,Noura]   | [2020,2022] |
--------------------------------------

IS_TRAIL

Check if a recursive relationship contains repeated relationships.

Input type	Output type
`RECURSIVE_REL`	`BOOLEAN`

MATCH p = (a:User)-[:Follows*2..2]-(b:User)
WHERE a.name='Adam'
RETURN properties(rels(p), '_id'), is_trail(p);

Output

-----------------------------------------
| PROPERTIES(RELS(p),_id) | IS_TRAIL(p) |
-----------------------------------------
| [2:1,2:1]               | False       |
-----------------------------------------
| [2:0,2:0]               | False       |
-----------------------------------------
| [2:1,2:2]               | True        |
-----------------------------------------
| [2:0,2:2]               | True        |
-----------------------------------------
| [2:1,2:3]               | True        |
-----------------------------------------

IS_ACYCLIC

Check if a recursive relationship contains repeated nodes.

Input type	Output type
`RECURSIVE_REL`	`BOOLEAN`

MATCH p = (a:User)-[:Follows*2..2]-(b:User)
WHERE a.name='Adam'
RETURN properties(nodes(p), 'name'), is_acyclic(p);

Output:

---------------------------------------------
| PROPERTIES(NODES(p),name) | IS_ACYCLIC(p) |
---------------------------------------------
| [Adam,Zhang,Adam]         | False         |
---------------------------------------------
| [Adam,Karissa,Adam]       | False         |
---------------------------------------------
| [Adam,Zhang,Karissa]      | True          |
---------------------------------------------
| [Adam,Karissa,Zhang]      | True          |
---------------------------------------------
| [Adam,Zhang,Noura]        | True          |
---------------------------------------------

LENGTH

Return the number of relationships (path length) in a recursive relationship.

MATCH p = (a:User)-[f:Follows*1..2]->(b:User)
RETURN LENGTH(p);

----------------
| LENGTH(p)    |
----------------
| 1            |
----------------
| 2            |
----------------
| 1            |
----------------
| 2            |
----------------

The LENGTH function when applied to a recursive relationship is shorthand for SIZE(rels(p)), which also returns the same result.