has_many with model name as foreign key

[fmh]

Hi,

It's possible to do this :

models:

• product has_many attributes
• user has_many attributes
• other_model has_many attributes
  

model attribute belongs to

• product , but the foreign_key is not product_id but the mode name (Product) stored in table attributes(id, name, model)
• user , but the  foreign_key is not product_id but the mode name (Product) stored in table attributes(id, name, model)

I want associate the attributes model with whole model and not with single record.

thx

[Vivek Sampara]

Hi,

Fistly, dont create a model with the name "Attribute". Some of the rails core methods uses "attributes" . Use something like "custom_attributes" . 

Next, to make a model belong_to different models on the same foreign_key, Make sure you use polymorphic-associations  in rails. 

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[fmh]

thx,

but with polymorphic associations, i always need to set a foreign key column,

my need is to set only the column type (model name)...

class Picture < ActiveRecord::Base
  belongs_to :imageable, polymorphic: true

#table pictures (id, name, imageable_id, imageable_type)
# how use it without imageable_id
end
 
class Employee < ActiveRecord::Base
  has_many :pictures, as: :imageable
end
 
class Product < ActiveRecord::Base
  has_many :pictures, as: :imageable
end

[Colin Law]

On 27 December 2014 at 16:19, fmh <aph...@gmail.com> wrote:
> thx,
>
> but with polymorphic associations, i always need to set a foreign key
> column,
>
> my need is to set only the column type (model name)...

Explain the problem that you are trying to solve with this unusual
scheme. It may well be that there is a better way of solving it.

Colin

[fmh]

i have many model that user want add or remove attribute dynamically

example :

table / model : product (id, name, price, metadata (serialized column , hash) )
table /mode : other_model (id, name, xxx_attribute, , metadata (serialized column , hash) )

table / model : my_custom_fields (id, name , field_type , model (column contain model name)  )

form and fields view are generate dynamically (with partial)

i can do it by :

class product < AR::Base
 serialize :metadata , Hash

#i save all my custom attributes in metadata column


 def get_all_custom_attributes
  My_custom_field.find_by_model(self.class.name)
 end

end

but i need a properly way if there is one ;)