instance method reload

Replaces the record attributes with the current values in the database.

This method finds the record by its primary key (which could be assigned manually) and modifies the receiver in-place:

account = Account.new
# => #<Account id: nil, email: nil>
account.id = 1
account.reload
# Account Load (1.2ms)  SELECT "accounts".* FROM "accounts" WHERE "accounts"."id" = $1 LIMIT 1  [["id", 1]]
# => #<Account id: 1, email: 'account@example.com'>

Internal state managed by Active Record, such as the associations cache is reset accordingly, but custom instance variables are left as-is.

If the record no longer exists in the database ActiveRecord::RecordNotFound is raised. Otherwise, in addition to the in-place modification the method returns self for convenience.

The optional :lock flag option allows you to lock the reloaded record:

reload(lock: true) # reload with pessimistic locking

Reloading is commonly used in test suites to test something is actually written to the database, or when some action modifies the corresponding row in the database but not the object in memory:

assert account.deposit!(25)
assert_equal 25, account.credit        # check it is updated in memory
assert_equal 25, account.reload.credit # check it is also persisted

Another common use case is optimistic locking handling:

def with_optimistic_retry
  begin
    yield
  rescue ActiveRecord::StaleObjectError
    begin
      # Reload lock_version in particular.
      reload
    rescue ActiveRecord::RecordNotFound
      # If the record is gone there is nothing to do.
    else
      retry
    end
  end
end