Grails: How to create formula on an embedded class - grails

Question

When I create a general class to embed it to other class, I want to add a transient property which is defined by a formula, but I do not how to implement this. Here is my source code:
//Embedded
class LocationInfo {
Long country, state, city
String address, fullAddress
static constraints = {
country nullable: true
state nullable: true
city nullable: true
address nullable: true
}
static mapping = {
country column: 'l_country'
state column: 'l_state'
city column: 'l_city'
address column: 'l_address'
fullAddress formula: "SELECT (l_address || ', ' || city.name) FROM system_location city WHERE city.id = l_city"
}
static transients = ['fullAddress']
}
class SystemLocation {
String name
Long parentLocationId
String level
static constraints = {
name blank: false, maxSize: 100
parentLocationId nullable: true
level inList: ['country', 'state', 'city']
}
static mapping = { version false }
}
//Host
class User {
String email
String password
String firstName
String lastName
Team team
UserLevel userLevel
boolean enabled = true
boolean accountExpired = false
boolean accountLocked = false
boolean passwordExpired = false
boolean teamLeader = false
LocationInfo locationInfo
AuditingInfo auditingInfo
static embedded = ['locationInfo', 'auditingInfo']
transient springSecurityService
static constraints = {
email blank: false, unique: true, maxSize: 200
password blank: false, maxSize: 200
firstName blank: false
lastName blank: false
team nullable: true
teamLeader nullable: true
locationInfo nullable: true
auditingInfo nullable: true
}
static mapping = {
team column: "team_id"
userLevel column: "user_level_id"
}
}
The LocationInfo is embedded to User class, nhưng when I get a specific user by ID and check the value in user.locationInfo.fullAddress, it is always NULL; and the generated SQL does not contains the "SELECT (l_address || ', ' || city.name)..." statement.
I do not know how to use a formula in an embedded class.
Could you please help me solve this?

Answer 1

According to the Grails manual there is no such thing like formula in the mapping settings.
I'd solve this by simply declaring a getter method on your domain class:
class LocationInfo {
Long country, state,
SystemLocation city
String address // n.b. no longAddress here
static constraints = {
country nullable: true
state nullable: true
city nullable: true
address nullable: true
}
static mapping = {
country column: 'l_country'
state column: 'l_state'
address column: 'l_address'
}
static transients = ['fullAddress']
String getFullAddress() {
"$address $city.name"
}
}
N.B. that city is now a reference to another domain class. In your draft this is just an id which makes your domain model hard to navigate.

Answer 2

I also had this problem and I think you can't do this that way.
When you define formula for some derived property, you have to put SQL with names of columns you know. But when this class is used in embedded property column names of that embedded object are changed.
In your case table User has columns location_info_l_city, location_info_l_address. But in formula you used names like l_city, l_address... There is no such column in table User.
I resolved the problem by adding derived property for embedded object's owner.
In your case I would add to class User mapping:
class User {
//...
String fullAddress
//...
static mapping = {
//...
fullAddress formula: "SELECT (location_info_l_address || ', ' || city.name) FROM system_location city WHERE city.id = location_info_l_city"
}
}
Now, you can use column User.fullAddress also in HQL queries.