(Quick Reference) ### Domain Class Usage A domain class fulfills the M in the Model View Controller (MVC) pattern and represents a persistent entity that is mapped onto an underlying database table. In Grails a domain is a class that lives in the `grails-app/domain` directory. A domain class can be created with the create-domain-class command:
    grails create-domain-class org.bookstore.Book
or with your favourite IDE or text editor.
    package org.bookstore

    class Book {
        String title
        Date releaseDate
        Author author
    }
The class name, by default, is mapped to the table name in lower case and separated by underscores instead of camel case so a domain class named `BookStore` by default would map to a table named `book_store`. Each property maps to individual columns. One limitation of the default table naming scheme is that it is problematic to have 2 domain classes with the same name, even if they are defined to be in separate packages. For example, `com.bookstore.BookStore` and `com.publishing.utility.BookStore` would each map to a table named `book_store`. If the 2 classes are defined in the application this problem can be managed by giving the classes different names or by providing a specific table name for one or both of the classes that deviates from the default (see the ORM DSL section of the user guide for more details). If one or both of the domain classes is provided by a plugin the application author may not have access to those options. To help manage a situation like that, GORM may be configured to prefix table names with plugin names by default. For example, if the `com.publishing.utility.BookStore` domain class is provided by a plugin named `PublishingUtilities`, the default table name could be `publishing_utilities_book_store`. To enable that behavior the `grails.gorm.table.prefix.enabled` config property must be set to true. Example: grails-app/conf/runtime.groovy
    grails.gorm.table.prefix.enabled = true
Refer to the configuration section of more details on defining configuration options. Refer to the user guide section on GORM for more information. #### Spring Autowiring of Domain Instances Since Grails 3.2.8, Spring autowiring of domain instances has been disabled by default because it represents a performance bottleneck. If you are autowiring services into your domain instances, you will need to re-enable it. For versions of Grails 3.3.0 or above, you can turn on autowire on a single domain class: grails-app/domain/demo/Book.groovy
    class Book {
        BookService bookService

        String name

       static mapping = {
           autowire true
       }
       ...
       ..
       .
    }
You can turn on autowire for all your domain classes using the Default Mapping setting: grails-app/conf/runtime.groovy
    grails.gorm.default.mapping = {
            autowire true
    }
For versions below Grails 3.3.0, you can re-enable it changing the `grails.gorm.autowire` configuration parameter. grails-app/conf/application.yml
    grails:
        gorm:
            autowire: true
| if Spring autowiring of domain instances is enabled, read performance will degrade.
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