我如何不包括最新记录，而是所有来自轨道对象的记录？

Question

For example if i want to pull all @posts using @posts.all but i dont want to include the very last or latest record from that?

here is what i am trying to do,

@posts = Post.all(Without the very very latest record that was created.)

Basically all record but not the very last record.

Answer 1

I think it is not worth it to try to generate a SQL query that excludes the very last element. Especially a subquery might be slower than just loading all records into an Array and than excluding the last:

@posts = Post.all[0..-2]

Your other example from the comments would look like this:

@contact_prices = @contact.retail_prices.all.order("created_at DESC").load[0..-2]

Another option (depending on the order of your relation) might be to use offset :

@contact_prices = @contact.retail_prices.order("created_at DESC").offset(1)

Answer 2

This is the most direct way I think of doing what you're trying to do:

Post.limit(Post.count - 1)

If you want your query to allow pagination or other LIMIT queries, you could try something like

Post.where("id < ?", Post.last.id)

Answer 3

很多答案可以解决问题，但会抛出其他选择：

@posts = Post.where("id != ?", Post.last.id)

Answer 4

一线AR：

Post.where.not(id: Post.last&.id)