GORM - get raw DB value for domain class properties - mongodb

Question

I'm using GORM for MongoDB in my Grails 3 web-app to manage read/writes from DB.
I have the following 2 domain classes:
class Company {
String id
}
class Team {
String id
Company company
}
For teams, their company is saved on DB as String, and with GORM I can simply use team.company to get an instance of Company domain class.
However, I need to override the getter for company, and I need the raw value for company id (as stored on DB), without GORM getting in the way and performing its magic.
Is there a way to get the raw String value?
Any help is welcome! Thanks in advance
Update (May 27)
Investigating #TaiwaneseDavidCheng suggestion, I updated my code to
class Company {
String id
}
class Team {
String id
Company company
String companyId
static mapping = {
company attr: "company" // optional
companyId attr: "company", insertable: false, updateable: false
}
}
Please note that I'm using GORM for MongoDB, which (citing the manual) tries to be as compatible as possible with GORM for Hibernate, but requires a slightly different implementation.
However I found out (by trial&error) that GORM for MongoDB doesn't support a similar solution, as it seems only one property at a time can be mapped to a MongoDB document property.
In particular the last property in alphabetical order wins, e.g. companyId in my example.
I figured out a way to make the whole thing work, I'm posting my own answer below.

Answer 1

given a non-insertable non-updateable column "companyId" in domain class
class Company {
String id
}
class Team {
String id
Company company
Long companyId
static mapping = {
company column:"companyId"
companyId column:"companyId",insertable: false,updateable: false
}
}

Answer 2

(Follows the edit to my question above)
I defined a custom mapping, and made use of Grails transients by also defining custom getter and setter for team's company.
class Company {
String id
}
class Team {
String id
Company company
String companyId
static mapping = {
companyId attr: "company" // match against MongoDB property
}
static transients = [ 'company' ] // non-persistent property
Company getCompany() {
return Company.get(companyId)
}
void setCompany(Company company) {
companyId = company.id
}
}