Question

I’m having a problem right now, I have 2 domain classes namely Doctor and Patient, where they have a 1:m relationship. here’s my code for class Doctor

class Doctor {

String name
String specialization

def doctorService

static hasMany = [patients: Patient]
static belongsTo = [hospital: Hospital]


static constraints = {

    name(blank:false)
    specialization(blank:false)
    patients(nullable:true)
    hospital(nullable:false)
}

String toString(){

    "Doctor ${name} "

}

}

–>and here’s my code for class Patient:

class Patient {

String name
String ailment
int age
Date dateAdmit, dateDischarge

static belongsTo = [doctor: Doctor, hospital: Hospital]

static constraints = {

    name(blank:false, maxSize:100)
    ailment(blank:false)
    age(size:1..200)
    dateAdmit(nullable:true)
    dateDischarge(nullable:true)
    hospital(nullable:false)
    doctor(nullable:false, validator:{val, obj -> val.hospital == obj.hospital})

}

String toString(){

    "${name} "

}
}

–>
I wanted to delete a doctor who doesn’t have a patient using executeUpdate(). I can select the doctors without patients using dynamic finders like this.

_

def d = Doctor.findAll("from Doctor as d where not exists" +
    "(from Patient as p where p.doctor = d)")

_

seems like that syntax doesn’t work in executeUpdate(), Im just a newbie in grails. please help me.. thanks…

Answer 1

Use this:

Doctor.executeUpdate('delete from Doctor d where d.patients is empty')