Check if a graph exists

We can check if a graph is stored in the catalog by looking up its name.

Syntax

Check if a graph exists in the catalog:

CALL gds.graph.exists(graphName: String) YIELD
  graphName: String,
  exists: Boolean

Table 1. Parameters
Name	Type	Optional	Description
graphName	String	no	The name under which the graph is stored in the catalog.

Table 2. Results
Name	Type	Description
`graphName`	String	Name of the removed graph.
`exists`	Boolean	If the graph exists in the graph catalog.

Additionally, to the procedure, we provide a function which directly returns the exists field from the procedure.

Check if a graph exists in the catalog:

RETURN gds.graph.exists(graphName: String)::Boolean

Examples

All the examples below should be run in an empty database.

The examples use Cypher projections as the norm. Native projections will be deprecated in a future release.

In order to demonstrate the GDS Graph Exists capabilities we are going to create a small social network graph in Neo4j and project it into our graph catalog.

The following Cypher statement will create the example graph in the Neo4j database:

CREATE
  (florentin:Person { name: 'Florentin', age: 16 }),
  (adam:Person { name: 'Adam', age: 18 }),
  (veselin:Person { name: 'Veselin', age: 20 }),
  (florentin)-[:KNOWS { since: 2010 }]->(adam),
  (florentin)-[:KNOWS { since: 2018 }]->(veselin)

Project Person nodes and KNOWS relationships:

MATCH (n:Person)-[r:KNOWS]->(m:Person)
RETURN gds.graph.project('persons', n, m)

Procedure

Check if graphs exist in the catalog:

UNWIND ['persons', 'books'] AS graph
CALL gds.graph.exists(graph)
  YIELD graphName, exists
RETURN graphName, exists

Table 3. Results
graphName	exists
"persons"	true
"books"	false

We can verify the projected persons graph exists while a books graph does not.

Function

As an alternative to the procedure, we can also use the corresponding function. Unlike procedures, functions can be inlined in other cypher-statements such as RETURN or WHERE.

Check if graphs exists in the catalog:

RETURN gds.graph.exists('persons') AS personsExists, gds.graph.exists('books') AS booksExists

Table 4. Results
personsExists	booksExists
true	false

As before, we can verify the projected persons graph exists while a books graph does not.