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If you wish to use GORM for Hibernate outside a Grails application you should declare the necessary dependencies for GORM and the database you are using, for example in Gradle:

[source,groovy,subs="attributes"]
----
implementation platform("org.apache.grails:grails-bom:{version}")
implementation "org.apache.grails.data:grails-data-hibernate7-core"
runtimeOnly "com.h2database"
runtimeOnly "org.apache.tomcat:tomcat-jdbc"
runtimeOnly "org.slf4j:slf4j-nop"
----

NOTE: The above example also uses the https://www.h2database.com[H2 Database] and Tomcat connection pool.
However, other pool implementations are supported including `commons-dbcp`, `tomcat pool` or `hikari`.
If a connection pool is not specified `org.springframework.jdbc.datasource.DriverManagerDataSource` is used,
which creates a new connection to the database each time you request a connection.
The latter will probably cause issues with an H2 in-memory database in that it will create a new in-memory
database each time a connection is requested, losing previously created tables.
Normal databases (`MySql`, `Postgres` or even file-based `H2`) are not affected.

Then create your entities in the `src/main/groovy` directory and annotate them with the `grails.gorm.annotation.Entity` annotation:

[source,groovy]
----
import grails.gorm.annotation.Entity
import org.grails.datastore.gorm.GormEntity

@Entity
class Person implements GormEntity<Person> { // <1>
    String firstName
    String lastName
    static constraints = {
        firstName blank:false
        lastName blank:false
    }
}
----
<1> Use of `GormEntity` is merely to aid IDE support outside of Grails.
When used inside a Grails context, some IDEs will use the
`grails-app/domain` location as a hint to enable code completion.

Then you need to place the bootstrap logic somewhere in your application which uses `HibernateDatastore`:

[source,groovy]
----
import org.grails.orm.hibernate.HibernateDatastore
Map configuration = [
    'hibernate.hbm2ddl.auto':'create-drop',
    'dataSource.url':'jdbc:h2:mem:myDB'
]
HibernateDatastore datastore = new HibernateDatastore(configuration, Person)
----

For more information on how to configure GORM see the <<configuration, Configuration>> section.
