Delete Records

This guide shows you how to delete records from the database.

Delete a Single Record

user = User.find(1)
user.try(&.delete!)
puts "User deleted"

Delete with delete!

Raises if record doesn't exist:

user = User.find!(1)
user.delete!

Delete with destroy!

destroy! triggers callbacks:

user = User.find!(1)
user.destroy!  # Runs before_destroy and after_destroy callbacks

Delete by ID

User.delete!(1)

Delete with Conditions

# Delete all inactive users
User.where(active: false).delete!

# Delete posts older than a year
Post.where { created_at < 1.year.ago }.delete!

Delete All Records

# Delete all comments
Comment.delete_all

# Delete all with condition
User.where(role: "guest").delete_all

Soft Delete (if enabled)

If using soft deletes:

user = User.find!(1)
user.delete!         # Sets deleted_at timestamp
user.deleted?        # => true

user.restore!        # Restores the record
user.deleted?        # => false

user.force_delete!   # Permanently removes from database

Cascade Delete

With foreign key cascade:

# If posts have: on_delete: :cascade
user = User.find!(1)
user.delete!  # Also deletes all user's posts

Delete Related Records First

Without cascade, delete children first:

user = User.find!(1)
user.posts.all.each(&.delete!)
user.delete!

Delete with Transaction

Ensure atomic deletion:

User.transaction do
  user = User.find!(1)
  user.posts.all.each(&.delete!)
  user.comments.all.each(&.delete!)
  user.delete!
end

Check Before Delete

user = User.find!(1)

if user.posts.count > 0
  puts "Cannot delete user with posts"
else
  user.delete!
end

Verify Deletion

user = User.find!(1)
user.delete!

User.find(1)  # => nil

Related

• Create Records

• Update Records

• Implement Soft Deletes