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boblu

2009-Aug-09 14:17 UTC

active record multiple table inheritance with abstract parent

I have four tables: jp_properties, cn_properties, jp_dictionaries and
cn_dictioanries.

And every jp_property belongs to a jp_dictionary with foreign key
"dictionary_id" in table.

Similarly, every cn_property belongs to a cn_dictionary with foreign
key "dictionary_id" in table too.

Since there are a lot of same functions in both property model and
both dictionary model, I''d like to group all these functions in
abstract_class.

The Models are like this:

class Property < AR::Base
  self.abstract_class = true
  belongs_to :dictionry,
             :foreign_key=>''dictionary_id'',
             :class=> ---ModelDomainName--- + "Dictionary"

  ### functions shared by JpProperty and CnProperty
end

class Dictionary < AR::Base
  self.abstract_class = true
  has_many :properties,
           :foreign_key=>''dictionary_id'',
           :class=> ---ModelDomainName--- + "Dictionary"

  ### functions shared by JpDictionary and CnDictionary
end

class JpProperty < Property
  :set_table_name :jp_properties
end

class CnProperty < Property
  :set_table_name :cn_properties
end

class JpDictionary < Dictionary
  :set_table_name :jp_dictionaries
end

class CnDictionary < Dictionary
  :set_table_name :cn_dictionaries
end

As you can see from the above code, the ---ModelDomainName--- part is
either ''Jp'' or ''Cn''. And I want to get these
string dynamically from
the instances of JpProperty, JpDictionary, CnProperty or CnDictionary.

For example:

tempJpProperty = JpProperty.first
tempJpProperty.dictionary #=> will get ''Jp'' from
tempJpProperty''s
class name and then apply it to the "belongs_to" declaration.

So the problem is I don''t know how to specify the ---
ModelDomainName--- part.

More specifically, I have no idea how to get subclass''s instance
object''s class name within the parent class''s body.

Can you please help me with this problem?

Michael Guterl

2009-Aug-09 20:30 UTC

head link

Re: active record multiple table inheritance with abstract parent

boblu wrote:> I have four tables: jp_properties, cn_properties, jp_dictionaries and
> cn_dictioanries.
> 
> And every jp_property belongs to a jp_dictionary with foreign key
> "dictionary_id" in table.
> 
> Similarly, every cn_property belongs to a cn_dictionary with foreign
> key "dictionary_id" in table too.
> 
> Since there are a lot of same functions in both property model and
> both dictionary model, I''d like to group all these functions in
> abstract_class.
> 
> The Models are like this:
> 
> class Property < AR::Base
>   self.abstract_class = true
>   belongs_to :dictionry,
>              :foreign_key=>''dictionary_id'',
>              :class=> ---ModelDomainName--- + "Dictionary"
> 
>   ### functions shared by JpProperty and CnProperty
> end
> 
> class Dictionary < AR::Base
>   self.abstract_class = true
>   has_many :properties,
>            :foreign_key=>''dictionary_id'',
>            :class=> ---ModelDomainName--- + "Dictionary"
> 
>   ### functions shared by JpDictionary and CnDictionary
> end
> 
> class JpProperty < Property
>   :set_table_name :jp_properties
> end
> 
> class CnProperty < Property
>   :set_table_name :cn_properties
> end
> 
> class JpDictionary < Dictionary
>   :set_table_name :jp_dictionaries
> end
> 
> class CnDictionary < Dictionary
>   :set_table_name :cn_dictionaries
> end
> 
> As you can see from the above code, the ---ModelDomainName--- part is
> either ''Jp'' or ''Cn''. And I want to get
these string dynamically from
> the instances of JpProperty, JpDictionary, CnProperty or CnDictionary.
> 
> For example:
> 
> tempJpProperty = JpProperty.first
> tempJpProperty.dictionary #=> will get ''Jp'' from
tempJpProperty''s
> class name and then apply it to the "belongs_to" declaration.
> 
> So the problem is I don''t know how to specify the ---
> ModelDomainName--- part.
> 
> More specifically, I have no idea how to get subclass''s instance
> object''s class name within the parent class''s body.
> 
> Can you please help me with this problem?
This is untested but worth a try.

class Property < AR::Base
  self.abstract_class = true
  def self.inherited(klass)
    klass.to_s =~ /(\w+)[A-Z].*/
    language = $1
    klass.belongs_to :dictionary, :foreign_key =>
''dictionary_id'',
                     :class => "#{language}Dictionary"
  end
end

class Dictionary < AR::Base
  self.abstract_class = true
  def self.inherited(klass)
    klass.to_s =~ /(\w+)[A-Z].*/
    language = $1
    klass.has_many :properties, :foreign_key =>
''dictionary_id'',
                   :class => "#{language}Property"
  end
end

Basically you have to delay the creation of the association until the 
subclass is created.

Best,
Michael Guterl
-- 
Posted via http://www.ruby-forum.com/.

boblu

2009-Aug-10 00:27 UTC

head link

Re: active record multiple table inheritance with abstract parent

Thanks a lot for your reply.

I just tried your suggestion, but I did not get luck.

This is the console output:

Jp::Property.first
TypeError: can''t dup NilClass
	from /rails/activerecord/lib/active_record/base.rb:2189:in `dup''
	from /rails/activerecord/lib/active_record/base.rb:2189:in
`scoped_methods''
	from /rails/activerecord/lib/active_record/base.rb:2193:in
`current_scoped_methods''
	from /rails/activerecord/lib/active_record/base.rb:2183:in `scope''
	from /rails/activerecord/lib/active_record/base.rb:2414:in
`set_readonly_option!''
	from /rails/activerecord/lib/active_record/base.rb:610:in `find''
	from /rails/activerecord/lib/active_record/base.rb:623:in `first''
	from (irb):2


Is there any other way to ''delay the creation of the association until
the subclass is created. ''?

Thank you

On 8月10日, 午前5:30, Michael Guterl
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> bobluwrote:
> > I have four tables: jp_properties, cn_properties, jp_dictionaries and
> > cn_dictioanries.
>
> > And every jp_property belongs to a jp_dictionary with foreign key
> > "dictionary_id" in table.
>
> > Similarly, every cn_property belongs to a cn_dictionary with foreign
> > key "dictionary_id" in table too.
>
> > Since there are a lot of same functions in both property model and
> > both dictionary model, I''d like to group all these functions
in
> > abstract_class.
>
> > The Models are like this:
>
> > class Property < AR::Base
> >   self.abstract_class = true
> >   belongs_to :dictionry,
> >              :foreign_key=>''dictionary_id'',
> >              :class=> ---ModelDomainName--- +
"Dictionary"
>
> >   ### functions shared by JpProperty and CnProperty
> > end
>
> > class Dictionary < AR::Base
> >   self.abstract_class = true
> >   has_many :properties,
> >            :foreign_key=>''dictionary_id'',
> >            :class=> ---ModelDomainName--- + "Dictionary"
>
> >   ### functions shared by JpDictionary and CnDictionary
> > end
>
> > class JpProperty < Property
> >   :set_table_name :jp_properties
> > end
>
> > class CnProperty < Property
> >   :set_table_name :cn_properties
> > end
>
> > class JpDictionary < Dictionary
> >   :set_table_name :jp_dictionaries
> > end
>
> > class CnDictionary < Dictionary
> >   :set_table_name :cn_dictionaries
> > end
>
> > As you can see from the above code, the ---ModelDomainName--- part is
> > either ''Jp'' or ''Cn''. And I want to
get these string dynamically from
> > the instances of JpProperty, JpDictionary, CnProperty or CnDictionary.
>
> > For example:
>
> > tempJpProperty = JpProperty.first
> > tempJpProperty.dictionary #=> will get ''Jp'' from
tempJpProperty''s
> > class name and then apply it to the "belongs_to"
declaration.
>
> > So the problem is I don''t know how to specify the ---
> > ModelDomainName--- part.
>
> > More specifically, I have no idea how to get subclass''s
instance
> > object''s class name within the parent class''s body.
>
> > Can you please help me with this problem?
>
> This is untested but worth a try.
>
> class Property < AR::Base
>   self.abstract_class = true
>   def self.inherited(klass)
>     klass.to_s =~ /(\w+)[A-Z].*/
>     language = $1
>     klass.belongs_to :dictionary, :foreign_key =>
''dictionary_id'',
>                      :class => "#{language}Dictionary"
>   end
> end
>
> class Dictionary < AR::Base
>   self.abstract_class = true
>   def self.inherited(klass)
>     klass.to_s =~ /(\w+)[A-Z].*/
>     language = $1
>     klass.has_many :properties, :foreign_key =>
''dictionary_id'',
>                    :class => "#{language}Property"
>   end
> end
>
> Basically you have to delay the creation of the association until the
> subclass is created.
>
> Best,
> Michael Guterl
> --
> Posted viahttp://www.ruby-forum.com/.

boblu

2009-Aug-10 13:19 UTC

head link

Re: active record multiple table inheritance with abstract parent

anyboby any ideas?

On 8月10日, 午前9:27, boblu <bobl...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Thanks a lot for your reply.
>
> I just tried your suggestion, but I did not get luck.
>
> This is the console output:
>
> Jp::Property.first
> TypeError: can''t dup NilClass
>         from /rails/activerecord/lib/active_record/base.rb:2189:in
`dup''
>         from /rails/activerecord/lib/active_record/base.rb:2189:in
> `scoped_methods''
>         from /rails/activerecord/lib/active_record/base.rb:2193:in
> `current_scoped_methods''
>         from /rails/activerecord/lib/active_record/base.rb:2183:in
`scope''
>         from /rails/activerecord/lib/active_record/base.rb:2414:in
> `set_readonly_option!''
>         from /rails/activerecord/lib/active_record/base.rb:610:in
`find''
>         from /rails/activerecord/lib/active_record/base.rb:623:in
`first''
>         from (irb):2
>
> Is there any other way to ''delay the creation of the association
until
> the subclass is created. ''?
>
> Thank you
>
> On 8月10日, 午前5:30, Michael Guterl
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
> wrote:
>
> > bobluwrote:
> > > I have four tables: jp_properties, cn_properties, jp_dictionaries
and
> > > cn_dictioanries.
>
> > > And every jp_property belongs to a jp_dictionary with foreign key
> > > "dictionary_id" in table.
>
> > > Similarly, every cn_property belongs to a cn_dictionary with
foreign
> > > key "dictionary_id" in table too.
>
> > > Since there are a lot of same functions in both property model
and
> > > both dictionary model, I''d like to group all these
functions in
> > > abstract_class.
>
> > > The Models are like this:
>
> > > class Property < AR::Base
> > >   self.abstract_class = true
> > >   belongs_to :dictionry,
> > >              :foreign_key=>''dictionary_id'',
> > >              :class=> ---ModelDomainName--- +
"Dictionary"
>
> > >   ### functions shared by JpProperty and CnProperty
> > > end
>
> > > class Dictionary < AR::Base
> > >   self.abstract_class = true
> > >   has_many :properties,
> > >            :foreign_key=>''dictionary_id'',
> > >            :class=> ---ModelDomainName--- +
"Dictionary"
>
> > >   ### functions shared by JpDictionary and CnDictionary
> > > end
>
> > > class JpProperty < Property
> > >   :set_table_name :jp_properties
> > > end
>
> > > class CnProperty < Property
> > >   :set_table_name :cn_properties
> > > end
>
> > > class JpDictionary < Dictionary
> > >   :set_table_name :jp_dictionaries
> > > end
>
> > > class CnDictionary < Dictionary
> > >   :set_table_name :cn_dictionaries
> > > end
>
> > > As you can see from the above code, the ---ModelDomainName---
part is
> > > either ''Jp'' or ''Cn''. And I
want to get these string dynamically from
> > > the instances of JpProperty, JpDictionary, CnProperty or
CnDictionary.
>
> > > For example:
>
> > > tempJpProperty = JpProperty.first
> > > tempJpProperty.dictionary #=> will get ''Jp''
from tempJpProperty''s
> > > class name and then apply it to the "belongs_to"
declaration.
>
> > > So the problem is I don''t know how to specify the ---
> > > ModelDomainName--- part.
>
> > > More specifically, I have no idea how to get subclass''s
instance
> > > object''s class name within the parent class''s
body.
>
> > > Can you please help me with this problem?
>
> > This is untested but worth a try.
>
> > class Property < AR::Base
> >   self.abstract_class = true
> >   def self.inherited(klass)
> >     klass.to_s =~ /(\w+)[A-Z].*/
> >     language = $1
> >     klass.belongs_to :dictionary, :foreign_key =>
''dictionary_id'',
> >                      :class => "#{language}Dictionary"
> >   end
> > end
>
> > class Dictionary < AR::Base
> >   self.abstract_class = true
> >   def self.inherited(klass)
> >     klass.to_s =~ /(\w+)[A-Z].*/
> >     language = $1
> >     klass.has_many :properties, :foreign_key =>
''dictionary_id'',
> >                    :class => "#{language}Property"
> >   end
> > end
>
> > Basically you have to delay the creation of the association until the
> > subclass is created.
>
> > Best,
> > Michael Guterl
> > --
> > Posted viahttp://www.ruby-forum.com/.

Ilan Berci

2009-Aug-10 13:27 UTC

head link

Re: active record multiple table inheritance with abstract parent

boblu wrote:> anyboby any ideas?
self.class.name() doesn''t work in the super?

-- 
Posted via http://www.ruby-forum.com/.

boblu

2009-Aug-10 14:08 UTC

head link

Re: active record multiple table inheritance with abstract parent

To IIan

Can you tell me what do you mean?

If you mean whether I tried the following

class Property < AR::Base
  self.abstract_class = true
  belongs_to :dictionary, :foreign_key => ''dictionary_id'',
:class => "#
{self.class.name.to_s[0..1]}Dictionary"
end

I can tell you it does not work, because the ''belongs_to''
declaration
will be evaluated in the abstract class and the sub class will only
inherit the methods generated by ''belongs_to''.

On 8月10日, 午後10:27, Ilan Berci
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> boblu wrote:
> > anyboby any ideas?
>
> self.class.name() doesn''t work in the super?
>
> --
> Posted viahttp://www.ruby-forum.com/.

Rails - Aug 2009 - active record multiple table inheritance with abstract parent

active record multiple table inheritance with abstract parent

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Re: active record multiple table inheritance with abstract parent

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