Hi,
Recently I've been playing around with destroy hooks in Sequel::Model.
Everything works as expected, but the qenerated SQL seems a bit
inefficient. Lets say I have this:
### Start code
require 'logger'
require 'sequel'
DB_NAME = 'foobar.db'
# Remove old db (if it exists)
File.delete(DB_NAME) if File.exists?(DB_NAME)
# Create new (sqlite) db
DB = Sequel.sqlite(DB_NAME, :loggers => Logger.new($stdout))
# Allow table creation from within the model
Sequel::Model.plugin(:schema)
class Foo < Sequel::Model
self.db = DB
self.set_schema do
primary_key :id
text :s1
text :s2
end
self.create_table unless self.table_exists?
def before_destroy
self.bars.each do |bar|
bar.destroy
end
end
end
class Bar < Sequel::Model
self.db = DB
self.set_schema do
primary_key :id
text :s1
integer :i1
foreign_key :foo_id
end
self.create_table unless self.table_exists?
end
# Associations
Foo.associate :one_to_many, :bars, :class => Bar, :key => :foo_id
Bar.associate :many_to_one, :foo, :class => Foo, :key => :foo_id
# Create some Foos and Bars
foo_1 = Foo.new
foo_1.s1 = 'foo_1'
foo_1.s2 = 'foo_1'
foo_1.save
bar_1 = Bar.new
bar_1.s1 = 'bar_1'
bar_1.i1 = 1
bar_1.foo = foo_1
bar_1.save
bar_2 = Bar.new
bar_2.s1 = 'bar_2'
bar_2.i1 = 2
bar_2.foo = foo_1
bar_2.save
bar_3 = Bar.new
bar_3.s1 = 'bar_3'
bar_3.i1 = 3
bar_3.foo = foo_1
bar_3.save
bar_4 = Bar.new
bar_4.s1 = 'bar_4'
bar_4.i1 = 4
bar_4.foo = foo_1
bar_4.save
# Print all Bars
puts Bar.all.inspect
# Destroy the Foo
foo_1.destroy
# Print all Bars
puts Bar.all.inspect
### End code
Whenever I remove a Foo I also want to remove all associated Bars. The
generated SQL code (for the before_destroy hook) looks like this:
I, [2011-03-24T14:11:20.784272 #7766] INFO -- : (0.000056s) BEGIN
I, [2011-03-24T14:11:20.784996 #7766] INFO -- : (0.000303s) SELECT *
FROM `bars` WHERE (`bars`.`foo_id` = 1)
I, [2011-03-24T14:11:20.785629 #7766] INFO -- : (0.000181s) DELETE
FROM `bars` WHERE (`id` = 1)
I, [2011-03-24T14:11:20.786088 #7766] INFO -- : (0.000089s) DELETE
FROM `bars` WHERE (`id` = 2)
I, [2011-03-24T14:11:20.786528 #7766] INFO -- : (0.000088s) DELETE
FROM `bars` WHERE (`id` = 3)
I, [2011-03-24T14:11:20.786966 #7766] INFO -- : (0.000083s) DELETE
FROM `bars` WHERE (`id` = 4)
I, [2011-03-24T14:11:20.787305 #7766] INFO -- : (0.000142s) DELETE
FROM `foos` WHERE (`id` = 1)
I, [2011-03-24T14:11:20.802552 #7766] INFO -- : (0.015104s) COMMIT
As seen in the trace, the before_destroy hook generates four SQL
calls, but ideally it should need just one:
DELETE FROM `bars` WHERE (`foo_id` = 1)
Is there a way to accomplish this within Sequel::Model? A
Foo.destroy_all_bars method or something?
/lasso
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