Retrieving value from database in Grails - grails

Question

I have one column named invoice_number in my database.
class Customer {
String name
int invoiceNumber
static constraints = {
name(blank: false)
invoiceNumber(unique: true)
}
}
There is no field for invoice_number in index.gsp file.
<g:form controller="customer">
Name:<br>
<g:textField name="name"></g:textField><br>
<g:actionSubmit value="Submit" action="Save"></g:actionSubmit><br>
</g:form>
I want to generate one invoice number and increase it with a difference of 5. For example, when first customer submits form, the invoice number may be generated as 105. When the second customer submits form, the invoice number should be 110. They should be saved in a database and they must be unique.
Then, I want to retrieve the invoice number from database for the customer who submits the form, and then, pass that invoice number to another gsp file.
How can I do it?

Answer 1

You need to add the logic of generating / incrementing the invoiceNumber in controller's action to which you are giving call on form submit.

Answer 2

Might get you started on your way (but I still don't get the 1 invoice per customer part, or incrementing by 5).
Yes, as mentioned by Abhinandan, you can put logic of ID creation in the controller, but a more reusable route might be to create a custom key generator, and point your class to use this generator for record IDs.
Suppose we have:
package tester2
class Custo {
String id // string just to show it can be anything
String name
// tell GORM about your id attribute, and setup your 'id' column
// to use a custom id generator function
static mapping = {
id column:"id", generator:"tester2.CustomIdGenerator"
}
}
then in src/groovy/tester2/CustomIdGenerator.groovy
package tester2
import org.hibernate.id.IdentifierGenerator
import org.hibernate.engine.spi.SessionImplementor
class CustomIdGenerator implements IdentifierGenerator {
public synchronized Serializable generate(SessionImplementor session, Object obj) {
// here's where you would have to access some persistent store to
// remember your last generated ID, fetch the last value, add 5,
// and store that new value to be ready for the next call
// -- don't know what DBMS you intend to use, but some have
// sequence support that will let you tinker with the starting
// point and increment. Maybe it's a simple as setting up a
// customized sequence and asking for nextVal()
//
// for this example, I just use a random UUID
return UUID.randomUUID().toString()
}
}