grails create-domain-class helloworld.Person
7.1 Quick Start Guide
Version: 4.0.0
Table of Contents
7.1 Quick Start Guide
A domain class can be created with the create-domain-class command:
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.
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You can customize the class by adding properties:
class Person {
String name
Integer age
Date lastVisit
}
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()