[Rails] Re: Rails 4 deprecation of in-place edit methods for collection associations

The justification for this change seems preposterous. Why would anyone think that, in the former example, the database has changed? The method called there is named "select!".

This sounds like a case of a few people writing fragile code without any understanding of what they were doing or the systems they work on, and complaining about it. I suggested that a simple bit of documentation would solve the problem. It doesn't seem to make much sense to make this particular interface so inconsistent with the rest of ActiveRecord, which absolutely allows you to modify objects in memory.

On Monday, September 23, 2013 9:59:52 AM UTC-4, Matt Jones wrote:

On Tuesday, 17 September 2013 00:43:15 UTC-5, George Georgiev wrote:

Hi everyone!

For those of you who are not noticed the in-place edit method for collection associations are broken in the current rails release - 4.0.0,

and here's what is cooking in the rails master https://github.com/rails/rails/commit/1a40be02113287d9a003f8224e91b9f623857f4b

and this https://github.com/rails/rails/pull/12227

In short: it looks like things like has_many.reject!{}, has_many.select!{}, has_many.delete_if{}, has_many.pop etc. will not work as of Rails 4.2.

I tried to get some answers about the motivation of this decision here https://github.com/rails/rails/pull/12236 but i failed.

So to the question can someone please explain WHY is this happening?

Where is the "confusion" in the examples above?

 Another related ticket: https://github.com/rails/rails/issues/12140

The problem is that using (for instance) delete_if on a collection removes things from the in-memory version but doesn't persist the changes. It *can't* persist the changes, since the records have been removed from the association's list of records. This is EXACTLY the "confusion" referenced in the tickets.

One of your examples in 12236 highlights this issue: these two code snippets (in Rails 3 or 4) do not do the same thing:

post.comments.select! { |comment| comment.not_spam? } 

# => filters the array in-memory but does not unlink objects

vs

comments = post.comments.to_a

comments.select! { |comment| comment.not_spam? }

post.comments = comments 

# => unlinks comments that aren't in the filtered array

--Matt Jones

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