Grails GORM (Grails Object Relational Mapping) allows you to define a number of validation rules that are carried through to your view when entering data.
For example with following simple Entity:
<code>
class Test1 {
Long id
Long version
String string1
Long testLong
Float float1
def constraints = {
string1(blank:false)
testLong(nullable:false,blank:false)
float1(nullable:false,blank:false)
}
...
}
</code>
The ‘constraints’ section defines the rules on the properties on this Entity – the rules are a comma separated list of name/value pairs for the rules to be applied. Notice the ‘blank’ only works on String properties. To require a value for any other property type, use ‘nullable:false’.
Here are some further self-explanatory examples from the online Grails docs:
<code>
def constraints = {
login(length:5..15,blank:false,unique:true)
password(length:5..15,blank:false)
email(email:true,blank:false)
age(min:new Date(),nullable:false)
}
</code>