I have several domain classes for which the user interface includes
a "duplicate" command. As part of the implementation of those commands,
I have implemented clone()
methods in the corresponding domain classes.
I have been trying to correct my bad habit of improperly implementing
clone() (in general) based on use of "new
" rather than "super.clone(),"
so as soon as I thought about doing the same for my Grails domain
classes, I wondered how using super.clone()
to obtain a clone might
interact with GORM
/ Hibernate persistence. In particular, I was
wondering about the proper way to handle the implicit "id" property. If
I simply super.clone()
, do nothing further and later try to save()
the
cloned instance, will it work properly (creating a new persistence
entry?) or will some kind of error or silent failure result?
What is the proper or preferred way to duplicate a Grails domain instance?
Add the following method to metaClass of the interface GormInstanceApi
which all domain implements it.
:
def cloneForDomains={def cloned=delegate.class.newInstance();
cloned.properties=delegate.properties;
return cloned;}
then :
org.grails.datastore.gorm.GormInstanceApi.clone=cloneForDomains ;
Congrats! now you can use clone
method such as save
, delete
.....
USE CASE :
Person p=Person.get(1);
Person cloned=p.clone();
cloned.id=null;
cloned.save();
UPDATE : you can loop all domain classes also :
grailsApplication.getDomainClasses().each{cls->
cls.metaClass.clone=cloneForDomains
}
UPDATE : for deep clone :
grailsApplication.getDomainClasses().each{cls->
cls.metaClass.clone={
return deepClone(delegate);
}
}
known that deepClone
is a method as following:
Object deepClone(domainInstanceToClone) {
//TODO: PRECISA ENTENDER ISSO! MB-249 no youtrack
//Algumas classes chegam aqui com nome da classe + _$$_javassist_XX
if (domainInstanceToClone.getClass().name.contains("_javassist"))
return null
//Our target instance for the instance we want to clone
// recursion
def newDomainInstance = domainInstanceToClone.getClass().newInstance()
//Returns a DefaultGrailsDomainClass (as interface GrailsDomainClass) for inspecting properties
GrailsClass domainClass = domainInstanceToClone.domainClass.grailsApplication.getDomainClass(newDomainInstance.getClass().name)
def notCloneable = domainClass.getPropertyValue("notCloneable")
for(DefaultGrailsDomainClassProperty prop in domainClass?.getPersistentProperties()) {
if (notCloneable && prop.name in notCloneable)
continue
if (prop.association) {
if (prop.owningSide) {
//we have to deep clone owned associations
if (prop.oneToOne) {
def newAssociationInstance = deepClone(domainInstanceToClone?."${prop.name}")
newDomainInstance."${prop.name}" = newAssociationInstance
} else {
domainInstanceToClone."${prop.name}".each { associationInstance ->
def newAssociationInstance = deepClone(associationInstance)
if (newAssociationInstance)
newDomainInstance."addTo${prop.name.capitalize()}"(newAssociationInstance)
}
}
} else {
if (!prop.bidirectional) {
//If the association isn't owned or the owner, then we can just do a shallow copy of the reference.
newDomainInstance."${prop.name}" = domainInstanceToClone."${prop.name}"
}
// @@JR
// Yes bidirectional and not owning. E.g. clone Report, belongsTo Organisation which hasMany
// manyToOne. Just add to the owning objects collection.
else {
//println "${prop.owningSide} - ${prop.name} - ${prop.oneToMany}"
//return
if (prop.manyToOne) {
newDomainInstance."${prop.name}" = domainInstanceToClone."${prop.name}"
def owningInstance = domainInstanceToClone."${prop.name}"
// Need to find the collection.
String otherSide = prop.otherSide.name.capitalize()
//println otherSide
//owningInstance."addTo${otherSide}"(newDomainInstance)
}
else if (prop.manyToMany) {
//newDomainInstance."${prop.name}" = [] as Set
domainInstanceToClone."${prop.name}".each {
//newDomainInstance."${prop.name}".add(it)
}
}
else if (prop.oneToMany) {
domainInstanceToClone."${prop.name}".each { associationInstance ->
def newAssociationInstance = deepClone(associationInstance)
newDomainInstance."addTo${prop.name.capitalize()}"(newAssociationInstance)
}
}
}
}
} else {
//If the property isn't an association then simply copy the value
newDomainInstance."${prop.name}" = domainInstanceToClone."${prop.name}"
if (prop.name == "dateCreated" || prop.name == "lastUpdated") {
newDomainInstance."${prop.name}" = null
}
}
}
return newDomainInstance
}
I've had much more luck with this method:
YourDomainClass clonedObject = new YourDomainClass(objectToClone.properties)
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