add two fields and insert into third in domain class in grails - grails

Question

I am working on a grails project in which i have a domain class having 3 fields. my requirement is to input only 2 fields and 3rd field get populated with the sum of both the fields. can anyone send me the code. thnks

Answer 1

See Derived properties
Example from above link
class Product {
Float price
Float taxRate
Float tax
static mapping = {
tax formula: 'PRICE * TAX_RATE'
}
}

Answer 2

Here's two complete ways of doing it, depending on your needs.
If you don't need to store the third field, meaning it's only used for display, you can do this:
class MyDomain {
int field1
int field2
static transients = ['field3']
getField3() {
field1 + field2
}
}
This will allow you to access the sum as myDomain.field3.
If you need to store it, say because it's heavily used in calculations, you can use events to automatically calculate and store the sum, like so:
class MyDomain {
int field1
int field2
int field3
def beforeInsert() {
field3 = field1 + field2
}
def beforeUpdate() {
field3 = field1 + field2
}
}
The benefit of doing it this way is that the third field is populated no matter where it's created or updated.
Two Notes:
If you only want to sum field3 when it's created, and not on updates, then remove beforeUpdate.
If you are doing more complex calculations than that simple sum, throw them in another method (like updateField3), and call that instead of hard-coding it.