default_scope and associations

user_184104 0
Viewed 9510

Suppose I have a Post model, and a Comment model. Using a common pattern, Post has_many Comments.

If Comment has a default_scope set:

default_scope where("deleted_at IS NULL")

How do I easily retrieve ALL comments on a post, regardless of scope? This produces invalid results:

Post.first.comments.unscoped

Which generates the following queries:

SELECT * FROM posts LIMIT 1;
SELECT * FROM comments;

Instead of:

SELECT * FROM posts LIMIT 1;
SELECT * FROM comments WHERE post_id = 1;

Running:

Post.first.comments

Produces:

SELECT * FROM posts LIMIT 1;
SELECT * FROM comments WHERE deleted_at IS NULL AND post_id = 1;

I understand the basic principle of unscoped removing all existing scopes, but shouldn't it be aware and to keep the association scope?

What is the best way to pull ALL comments?

default-scope ruby-on-rails
6 Answers

with_exlusive_scope is deprecated as of Rails 3. See this commit.

Before (Rails 2):

Comment.with_exclusive_scope { Post.find(post_id).comments }

After (Rails 3):

Comment.unscoped { Post.find(post_id).comments }
user_2315290

How about this?

# Use this scope by default
scope :active, -> { where(deleted_at: nil) }

# Use this whenever you want to include all comments regardless of their `deleted_at` value
scope :with_soft_deleted, -> { unscope(where: :deleted_at)

default_scope, -> { active }

post.comments would fire this query:

SELECT "comments".* FROM "comments" WHERE "comments"."deleted_at" IS NULL AND "comments"."post_id" = $1;

post.comments.with_soft_deleted would send this:

SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = $1;
user_27826180
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