Rails - Dec 2006 - ActiveRecord: adding children to a has_many parent

given parent.list is a has_many of Child, I''ve found that if I do this:

    child = Child.new(...)
    parent.list << child

rails will select * all of parent.list before doing the insert of the
new child (if parent.list isn''t already loaded). This is -bad- because
my parent.list is huge.

So instead, I do this:

    child = Child.new(...)
    child.parent = parent
    child.save!

This ensures a single insert and also throws an exception if any DB
constraints are violated, thus ensuring any encompassing transactions
and/or top level logging is handled.

is this generally the right thing to do with rails? I''m a noob coming
from enterprise development in other languages.

Or is there some other magic way to add to parent.list with the above
kind behavior?


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bataras wrote:
> 
> given parent.list is a has_many of Child, I''ve found that if I do
this:
> 
>    child = Child.new(...)
>    parent.list << child
> 
> rails will select * all of parent.list before doing the insert of the
> new child (if parent.list isn''t already loaded). This is -bad-
because
> my parent.list is huge.
> 
> So instead, I do this:
> 
>    child = Child.new(...)
>    child.parent = parent
>    child.save!
The most terse way would be

   parent.list.create(...)

If you want to defer saving you can instead use the "build" method.

-- 
We develop, watch us RoR, in numbers too big to ignore.


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Cool. Thanks. I''ll use that. In one case though, I have to create a new
child that "belongs_to" 2 different kinds of parents. So for that,
I''ll
have to use the build method to make it happen in a single insert.


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