Hi, sequel developer. This product is very great.
I have a question about the Model#association_join with 3 tables.
In the following code, is there any way to retrieve created_at of Parent?
```
Parent.first.created_at
=> 2016-03-09 09:11:25 +0900
GrandChild.first.created_at
=> 2016-03-09 09:11:30 +0900
r = Parent.association_join(:child => :grand_child).first
r.class
=> Parent
r.created_at
=> 2016-03-09 09:11:30 +0900 ## OMG! this is GrandChild's value
```
I guess, this behavior is non-intuitive.
Currently, I have a workaround, using Alias feature.
```
r = Parent.select_append(Sequel.as(Sequel.qualify(:parents, :created_at),
:hoge)).association_join(:child => :grand_child).first
r.created_at
=> 2016-03-09 09:11:30 +0900
r[:hoge]
=> 2016-03-09 09:11:25 +0900 ## Great! (but cannot use #hoge ...)
```
Thank you.
Inspection code and result;
```
require "sequel"
DB = Sequel.sqlite
DB.create_table :grand_children do
primary_key :id
Integer :child_id
String :name
DateTime :created_at
end
DB.create_table :children do
primary_key :id
Integer :parent_id
String :name
DateTime :created_at
end
DB.create_table :parents do
primary_key :id
String :name
DateTime :created_at
end
class GrandChild < Sequel::Model
plugin :timestamps
many_to_one :child
end
class Child < Sequel::Model
plugin :timestamps
many_to_one :parent
one_to_many :grand_child
end
class Parent < Sequel::Model
plugin :timestamps
one_to_many :child
end
## main
# Create data
p1 = Parent.create(name: "p1") ; sleep 2
c1 = p1.add_child(name: "c1") ; sleep 2
_ = c1.add_grand_child(name: "g1")
# Inspect
r1 = Parent.association_join(:child => :grand_child).first
r2 = GrandChild.association_join(:child => :parent).first
puts <<-EOT
## created_at of each table
Parent: #{Parent.first.created_at}
Child: #{Child.first.created_at}
GrandChild: #{GrandChild.first.created_at}
## check joined created_at
Lookup path(top-down) : Parent => Child => GrandChild
Return class is #{r1.class}
created_at: #{r1.created_at}
(#{r1.class}'s created_at is #{r1.class.first.created_at})
Lookup path(bottom-up): Parent <= Child <= GrandChild
Return class is #{r2.class}
created_at: #{r2.created_at}
(#{r2.class}'s created_at is #{r2.class.first.created_at})
EOT
r = Parent.select_append(Sequel.as(Sequel.qualify(:parents, :created_at),
:hoge)).association_join(:child => :grand_child).first
puts <<-EOT
## workaround
Return class is #{r.class}
created_at: #{r.created_at}
hoge: #{r[:hoge]}
(#{r.class}'s created_at is #{r.class.first.created_at})
EOT
```
```
$ bundle exec ruby sequel_association_join_value_of_same_column.rb
## created_at of each table
Parent: 2016-03-09 09:14:18 +0900
Child: 2016-03-09 09:14:20 +0900
GrandChild: 2016-03-09 09:14:22 +0900
## check joined created_at
Lookup path(top-down) : Parent => Child => GrandChild
Return class is Parent
created_at: 2016-03-09 09:14:22 +0900
(Parent's created_at is 2016-03-09 09:14:18 +0900)
Lookup path(bottom-up): Parent <= Child <= GrandChild
Return class is GrandChild
created_at: 2016-03-09 09:14:18 +0900
(GrandChild's created_at is 2016-03-09 09:14:22 +0900)
## workaround
Return class is Parent
created_at: 2016-03-09 09:14:22 +0900
hoge: 2016-03-09 09:14:18 +0900
(Parent's created_at is 2016-03-09 09:14:18 +0900)
```
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