Issue with PR #1639

[georgempla]

Bug: Shipping a project fails with postable can't be blank

Introduced by: #1639 (commit 778654b)

Cause:The commit added validates :postable_id, presence: true to Post. This validation fires before Rails has a chance to persist the associated Post::ShipEvent and assign it an id. Since postable_id is still nil at validation time (the record hasn't been saved yet), the validation fails and the whole transaction is aborted.

Fix: Replace the column-level validations with an association-level one:

# Remove these:
validates :postable_id, presence: true
validates :postable_type, presence: true

# Add this instead:
validates :postable, presence: true

This validates the object reference rather than the raw foreign key column, so it works correctly with delegated_type's autosave behaviour.

[georgempla]

issue resolved with reversion of #1639 #1642