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GORM for Neo4j will create Neo4j relationships between nodes for you based on the relationship ownership rules defined in your GORM mapping. For example the following mapping:

[source,groovy]
----
include::{testsdir}/grails/gorm/tests/cypher/domain/Owner.groovy[tags=class,indent=0]
include::{testsdir}/grails/gorm/tests/cypher/domain/Pet.groovy[tags=class,indent=0]
----

When you save the relationship:

[source,groovy]
----
include::{testsdir}/grails/gorm/tests/cypher/OneToManyCreateSpec.groovy[tags=save,indent=0]
----

The `save()` method will generate a Cypher relationship creation query as follows:

[source,cypher]
----
MATCH (from:Owner),(to:Pet) WHERE ID(from) = {start} AND ID(to) IN {end} MERGE (from)-[r:PETS]->(to)
----

As you can see from the query the relationship is defined as `(from)-[r:PETS]->(to)`, with the direction of the association defined by who "owns" the association. Since `Pet` defines a `belongTo` association to `Owner`, this means that `Owner` owns the association and the relationship is from `Owner` to `Pet`.

You can customize the Neo4j relationship type and direction using the `mapping` block if necessary:

[source,groovy]
----
import static grails.neo4j.Direction.*

class Owner {
    String name
    static hasMany = [pets:Pet]

    static mapping = {
         pets type:"PETZ", direction:BOTH
    }
}
----

In this case a bidirectional relationship will be created  in the graph such as `(from)<-[r:PETZ]->(to)`.

TIP: For more information on defining relationships with GORM, see the https://grails.apache.org/docs/latest/guide/GORM.html#gormAssociation[corresponding guide in the GORM documentation].
