Rails nested attributes validation force save parent firstly - ruby

Question

I have 2 models like:
class Father < ActiveRecord::Base
has_many :children
accepts_nested_attributes_for :children
end
class Child < ActiveRecord::Base
belongs_to :father
validate :validate_money
def validate_money
children = Child.where(id: self.father.id)
sum_of_children_pocket_money = my_func # function for getting sum of all pocket money of all children
if sum_of_children_pocket_money > self.father.money
errors.add(:pocket_money, "My error message!!!")
end
end
end
and initially I have:
and when pass passengers_attributes to update customer (id=1) like
{
id: 1,
name: "Father 1",
money: 1000,
children: [
{
name: "Child 1",
id: 1,
pocket_money: 500
}
]
}
and then I am sending for update:
{
id: 1,
name: "Father 1",
money: 2000,
children: [
{
name: "Child 1",
id: 1,
pocket_money: 1500
}
]
}
So I am getting an error in my validation because it starts sum_of_children_pocket_money > self.father.money comparison and sum_of_children_pocket_money is equal to 1500 but self.father.money still 1000. How can I fix this?

Answer 1

Moving the validation logic from Child to Father should solve the problem.
class Father < ActiveRecord::Base
has_many :children
accepts_nested_attributes_for :children
validate :validate_money
def validate_money
children = Child.where(id: id)
sum_of_children_pocket_money = my_func # function for getting sum of all pocket money of all children
if sum_of_children_pocket_money > money
errors.add(:pocket_money, "My error message!!!")
end
end
end
class Child < ActiveRecord::Base
belongs_to :father
end