7.1 Quick Start Guide 3.2.3

(Quick Reference) # 7.1 Quick Start Guide Version: 3.2.3 ## Table of Contents ## 7.1 Quick Start Guide A domain class can be created with the create-domain-class command:
    grails create-domain-class helloworld.Person
| If no package is specified with the create-domain-class script, Grails automatically uses the application name as the package name.
This will create a class at the location `grails-app/domain/helloworld/Person.groovy` such as the one below:
    package helloworld

    class Person {
    }
| If you have the `dbCreate` property set to "update", "create" or "create-drop" on your DataSource, Grails will automatically generate/modify the database tables for you.
You can customize the class by adding properties:
    class Person {
        String name
        Integer age
        Date lastVisit
    }
Once you have a domain class try and manipulate it with the shell or console by typing:
    grails console
This loads an interactive GUI where you can run Groovy commands with access to the Spring ApplicationContext, GORM, etc. ## 7.1.1 Basic CRUD Try performing some basic CRUD (Create/Read/Update/Delete) operations. ### Create To create a domain class use Map constructor to set its properties and call save:
    def p = new Person(name: "Fred", age: 40, lastVisit: new Date())
    p.save()
The save method will persist your class to the database using the underlying Hibernate ORM layer. ### Read Grails transparently adds an implicit `id` property to your domain class which you can use for retrieval:
    def p = Person.get(1)
    assert 1 == p.id
This uses the get method that expects a database identifier to read the `Person` object back from the database. You can also load an object in a read-only state by using the read method:
    def p = Person.read(1)
In this case the underlying Hibernate engine will not do any dirty checking and the object will not be persisted. Note that if you explicitly call the save method then the object is placed back into a read-write state. In addition, you can also load a proxy for an instance by using the load method:
    def p = Person.load(1)
This incurs no database access until a method other than getId() is called. Hibernate then initializes the proxied instance, or throws an exception if no record is found for the specified id. ### Update To update an instance, change some properties and then call save again:
    def p = Person.get(1)
    p.name = "Bob"
    p.save()
### Delete To delete an instance use the delete method:
    def p = Person.get(1)
    p.delete()
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