Nested forms: use validate :some_method works in update mode only

I have a strange behavior when validating a record in a nested form. The
association collection is empty when creating a new record and the
validation does not catch the error. But when updating the same record
validation gets it right but continues to catch the error even after
modifying the needed attribute value to make it pass.

Here is the model:


class Timesheet < ActiveRecord::Base
attr_accessible :status, :user_id, :start_date, :end_date,

SUBMITTED = ‘Submitted’
APPROUVED = ‘Approuved’
REJECTED = ‘Rejected’

belongs_to :user
has_many :activities, dependent: :destroy, inverse_of: :timesheet
has_many :time_entries, through: :activities
accepts_nested_attributes_for :activities, allow_destroy: true

validates :user_id, presence: true
validates :status, presence: true, inclusion: {in: STATUS_VALUES}
validate :maximum_worktime_per_day

after_update :check_an_activity_present

after_initialize :init_working_week

def maximum_worktime_per_day
time_entries_by_date = time_entries.group_by(&:workdate)
time_entries_by_date.each do |key, value|
errors[:base] << “Maximum daily time should not exceed 1 day” if > 1

As I could see the output in the console, when creating a new record,
hash ‘ime_entries_by_date’ in the validation method is empty, that’s why
the record is saved without problems even if the worktime exceeds the
validation value of 1 day.
When updating the same record, the validation method catches well the
but does not refresh the hash values even after I modify the work time
values to make it pass.
Any idea how to fix that?

Thank you