Grails：重复项和唯一约束验证

Question

OK here is stripped down version of what I have in my app

Artist domain:

class Artist {

    String name
    Date lastMined
    def artistService

    static transients = ['artistService']
    static hasMany = [events: Event]

    static constraints = {
        name(unique: true)
        lastMined(nullable: true)
    }

    def mine() {
        artistService.mine(this)
    }
}

Event domain:

class Event {

    String name
    String details
    String country
    String town
    String place
    String url
    String date

    static belongsTo = [Artist]
    static hasMany = [artists: Artist]

    static constraints = {
        name(unique: true)
        url(unique: true)
    }
}

ArtistService:

class ArtistService {

    def results = [
        [
            name:"name",
            details:"details",
            country:"country",
            town:"town",
            place:"place",
            url:"url",
            date:"date"
        ]
    ]

    def mine(Artist artist) {
        results << results[0] // now we have a duplicate
        results.each {
            def event = new Event(it)
            if (event.validate()) {
                if (artist.events.find{ it.name == event.name }) {
                    log.info "grrr! valid duplicate name: ${event.name}"
                }
                artist.addToEvents(event)
            }
        }

        artist.lastMined = new Date()
        if (artist.events) {
            artist.save(flush: true)
        }
    }
}

In theory event.validate() should return false and event will not be added to artist, but it doesn't.. which results in DB exception on artist.save()

Although I noticed that if duplicate event is persisted first everything works as intended. Is it bug or feature? :P

Answer 1

Which version of Grails? I've just tested this code in the Grails 1.3.1 console:

new Book(title: "Misery", author: "Stephen King").save()
new Book(title: "The Shining", author: "Stephen King").save()
new Book(title: "Colossus", author: "Niall Ferguson").save(flush: true)

def b = new Book(title: "Colossus", author: "Stephen King")
assert !b.validate()
println b.errors

The assertion passed and the last line generated output like:

org.springframework.validation.BeanPropertyBindingResult: 1 errors
Field error in object 'Book' on field 'title': rejected value [Colossus]; codes [Book.title.unique.error.Book.title,...

Perhaps it was a bug that's now fixed?

Answer 2

You should replace artist.addToEvents(event) by artist.addToEvents(event).save() and it will work. Till you didn't call save() method, the validation will not take into account the new created event