# What's the advantage of using build and \<\\
**Category:** Rails\
**Created:** [December 24, 2008, 5:32am UTC](https://www.ruby-forum.com/t/whats-the-advantage-of-using-build-and/156302 "2008-12-24T05:32:41Z")\
**Posts on this page:** 5\
**Page:** 1
**Author:**  [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [December 24, 2008, 5:32am UTC](https://www.ruby-forum.com/t/whats-the-advantage-of-using-build-and/156302/1 "2008-12-24T05:32:41Z")
Rails give us two ways to create a asociation object:
@article = Article.new(params[:article])
@article.comments \<\< Comment.new(params[:comment])
@article.save!
or
@article = Article.new(params[:article])
@comment = @article.comments.build(params[:comment])
@article.save!
@comment.save!
what’s the advantage of using build and \<\< ??
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**Author:**  [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [December 24, 2008, 7:35am UTC](https://www.ruby-forum.com/t/whats-the-advantage-of-using-build-and/156302/2 "2008-12-24T07:35:32Z")
## \<\< should save @article when you add a new comment.
Ryan B.
Freelancer
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>
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**Author:**  [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [December 24, 2008, 10:59am UTC](https://www.ruby-forum.com/t/whats-the-advantage-of-using-build-and/156302/3 "2008-12-24T10:59:47Z")
\<\< adds records to a association-collection (no matter what kind of
association). it returns itself (the collection) so method calls may
be chained.
btw: in this example @article doesn’t have to be saved when a new
comment is added (comment has article\_id as foreign key). 😉
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**Author:**  [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [December 24, 2008, 11:02am UTC](https://www.ruby-forum.com/t/whats-the-advantage-of-using-build-and/156302/4 "2008-12-24T11:02:09Z")
just saw that this could be misunderstood:
article has to be saved to be able to make a association, but it
doesn’t have to be saved after adding a new comment.
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**Author:**  [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [December 24, 2008, 3:29pm UTC](https://www.ruby-forum.com/t/whats-the-advantage-of-using-build-and/156302/5 "2008-12-24T15:29:38Z")
MaD wrote:
> \<\< adds records to a association-collection (no matter what kind of
> association). it returns itself (the collection) so method calls may
> be chained.
>
> btw: in this example @article doesn’t have to be saved when a new
> comment is added (comment has article\_id as foreign key). 😉
what’s does that -method calls may be chained-? can you make me a
concrete example?
in this example @article doesn’t have to be saved when a new
> comment is added (comment has article\_id as foreign key)
> =
> @article = Article.new(params[:article])
> don’t we have to save it for store a Article instance?