Composite keys and association

i have two table, comment and post, both have composite keys, and no id
column, comment belongs to post, i follow the instruction of
http://compositekeys.rubyforge.org/, and it seems successfully,
(But i still cant confirm to put require ‘rubygems’ and
require ‘composite_primary_keys’ on which file ).
I can do the CRUD operation for post,then i want to create comment form,
in the _form.html.erb, the code likes below:
<%= form_for([@post, @post.comments.build]) do |f| %>
then i got an error,“unknown attribute: comment_id”,
i think the build method need the parameter id which is default, but i
dont have this column,and i cant change any thing in the database,how to
resolve this problem?Thanks .

On 5 January 2012 02:53, Daisy Di [email protected] wrote:

dont have this column,and i cant change any thing in the database,how to
resolve this problem?Thanks .

A way to resolve the problem is to stick to the rails conventions for
id columns and so on. That is the best way unless you have a legacy
database and really cannot change the schema.

Colin

Colin L. wrote in post #1039519:

On 5 January 2012 02:53, Daisy Di [email protected] wrote:

dont have this column,and i cant change any thing in the database,how to
resolve this problem?Thanks .

A way to resolve the problem is to stick to the rails conventions for
id columns and so on. That is the best way unless you have a legacy
database and really cannot change the schema.

Colin

Hi Colin,
i really have a legacy database and cant change anything…
thanks very much

On 6 January 2012 01:10, Daisy Di [email protected] wrote:

Hi Colin,
i really have a legacy database and cant change anything…
thanks very much

In that case some of the clever stuff in Rails may not be available to
you, you may have to do them ‘by hand’ so to speak. I don’t know
whether there is a way of using build in the way you want in your
circumstance. The alternative is just to create the object
explicitly. I expect you have already googled for
rails legacy database
to get as far as you have.

Colin

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