Rails core - Jun 2013 - A puzzle about default_scope

Hi, guys

I have a puzzle about default_scope.

Suppose I have two model:

class User < ActiveRecord::Base
  has_many :blogs
  default_scope where(deleted_at: nil)
end

class Blog < ActiveRecord::Base
  belongs_to :user
end

I want to produce sqlselect blogs.* from blogs inner join users on users.id 
= blogs.user_id and users.deleted_at is null

And the code Blog.joins(:user), which I think is good, produceselect 
blogs.* from blogs inner join users on users.id = blogs.user_id

The default_scope is not appended to the join condition, why?

To reach my goal, I must add conditions to belongs_to:

class Blog < ActiveRecord::Base
  belongs_to :user, conditions: "deleted_at is null"
end

Why not append default_scope to join condition directly as the doc said:

Use this macro in your model to set a default scope for all operations on 
the model.

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I came across this exact same behavior about three months ago.

If every other access to an AR class with a default scope honors that scope in
the generated SQL, why not in a join situation?

Wes

Sent from my iPhone

On Jun 15, 2013, at 9:37 AM, soffolk Zhu <zlx.star@gmail.com> wrote:
> Hi, guys
> 
> I have a puzzle about default_scope.
> 
> Suppose I have two model:
> 
> class User < ActiveRecord::Base
>   has_many :blogs
>   default_scope where(deleted_at: nil)
> end
> 
> class Blog < ActiveRecord::Base
>   belongs_to :user
> end
> I want to produce sqlselect blogs.* from blogs inner join users on users.id
= blogs.user_id and users.deleted_at is null
> 
> And the code Blog.joins(:user), which I think is good, produceselect
blogs.* from blogs inner join users on users.id = blogs.user_id
> 
> The default_scope is not appended to the join condition, why?
> 
> To reach my goal, I must add conditions to belongs_to:
> 
> class Blog < ActiveRecord::Base
>   belongs_to :user, conditions: "deleted_at is null"
> end
> Why not append default_scope to join condition directly as the doc said:
> 
> Use this macro in your model to set a default scope for all operations on
the model.
> -- 
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Core" group.
> To unsubscribe from this group and stop receiving emails from it, send an
email to rubyonrails-core+unsubscribe@googlegroups.com.
> To post to this group, send email to rubyonrails-core@googlegroups.com.
> Visit this group at http://groups.google.com/group/rubyonrails-core.
> For more options, visit https://groups.google.com/groups/opt_out.
>  
>  
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