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hibernatejpagrailsormgrails-orm

Grails: Pain of adding multiple child elements to a parent domain object

I am relatively new to Grails/GORM and I have very less exposure to hibernate before this.

I am trying to map child objects to parent object in grails. I have multiple child objects to map. Child objects already exist in the database.

class Parent {
    static hasMany = [children: Child]
}

class Child {
    String name
}

I have tried the following steps,

def parentId = <a valid parent domain id>
def parent = Parent.get(parentId)
def children = Children.getAll([list of valid children ids])

I tried the addTo* with a list of child objects and it did not work. 

parent.addToChildren(children)

It mapped only the first element from the list.

I also tried the following snippet, it did not work either.

parent.children += children
parent.save(flush:true)

I wasn't able to find a way to do this without using a loop. I believe that I'm missing something here.

Solution

  • Try this: children.each { parent.addToChildren(it) }

    The addTo only accepts a single instance, not a list. So iterate the list and add the individual instances.