Unique Constraint over values of two domain classes in Grails - mongodb

Question

I have two domain classes. One is :
class User {
String login
String password
String firstName
String lastName
String address
String email
static constraints = {
login blank:false, size:5..15,matches:/[\S]+/, unique:true
password blank:false, size:5..15,matches:/[\S]+/
firstName blank:false
lastName blank:false
email email: true
}
}
And other is
class AddWebsite {
String website
User user
static constraints = {
website blank:false
website(unique: ['user'])
}
}
I am working with MongoDB at the backend. I need that for a particular login value, all siteURL values should be unique. Ex: login = abc#gmail.com. Then this user can have all unique url only in the database. But same urls can exist for different users. How do I do that using the unique constraint or any other approach?

Answer 1

Use embedded sub-documents to store SiteURL instances right inside the User. Then you define the collection to be a Set, which makes sure, all it's entries are unique. If you want to use the default mongo collection types or want to persist the order, define an interceptor like:
def beforeSave = {
urls = urls.unique()
}
UPDATE:
If your urls are plain strings, use the default primitive collection (no hasMany):
class User {
String login
//...
Set urls = new HashSet()
}

Answer 2

In this case you should be able to place unique constraint on the AddWebsite domain class such as this:
class AddWebsite {
String website
User user
static constraints = {
website(blank:false, unique: ['user'])
}
}
This will ensure that each website is unique in the database per user. Notice that multiple constraints are applied to the property website.
edited to match updated question.

Answer 3

It finally worked. I was getting the user cannot be null error while entering the website though it was not being validated in the AddWebsite domain class. I made the following changes and got it to work:
class AddWebsite{
String website
User user
static belongsTo = [user: User]
static constraints = {
website( url:true, unique: ['user'])
}
}
And in my controller also, I set the value of the user object to the session variable:
def addWebsites() {
if(request.method == 'POST') {
def w = new AddWebsite()
w.properties[
'website'
] = params
w.user = session["user"] //modified to make it work
if(w.save()) {
render view:'addWebsites', model:[message: "Successfully saved"]
}
else {
return [addWebsite:w]
}
}
Hope it helps someone :)