The Grails Framework 3.2.4

(Quick Reference) ## ignoreNotFound ### Purpose Specifies how foreign keys that reference missing rows are handled in many-to-one relationships. ### Examples
    class LegacyCdDomain {

        String title
        Thumbnail thumbnail

        static mapping = {
            thumbnail ignoreNotFound: true
        }
    }
    class Thumbnail {
        byte[] data
    }
### Description Usage: `association_name(ignoreNotFound: boolean)` When the data in the database is corrupt and a foreign key references a non existent record, Hibernate will complain with a "No row with the given identifier exists" message. For example, a `LegacyCdDomain` record may have a reference to a `Thumbnail` record with an ID of 1234, but the database may no longer contain a `Thumbnail` with that ID. One possible way to load such corrupt data is to use the `ignoreNotFound` mapping option. If you set it to `true`, Hibernate will treat a missing row as a `null` association. So in the above example, our `LegacyCdDomain` instance would load but its `thumbnail` property would be `null`. Specifying a value of `false` for `ignoreNotFound` will result in Hibernate throwing an `org.hibernate.ObjectNotFoundException`.
| A dataset loaded with `ignoreNotFound: true` may throw an exception during `save()` because of the missing reference!
The default value for this setting is `false`. It maps to Hibernate’s `not-found` property. This settings can be useful if you have a legacy database with unusual behaviour when it comes to referential integrity. | Quick Reference (hide)