CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3ruby-on-rails-3.1rubygems
LondonGuy
LondonGuy

Reputation: 11098

How would I destroy_all or delete_all records except one in ruby on rails?

I'm using "acts_as_tree" plugin for my user messaging thread feature on my website. I have a method that makes deleting selected messages possible. The messages don't actually get deleted. Their sender_status or recipient_status columns get set to 1 depending on what user is the sender or recipient of the message.

Anyway if both users have those status's set to one then that last line makes sure the message row is completely moved from the database. Now this is fine as long as it's not the parent message being deleted. If the parent message deleted then the children that haven't been selected for deletion won't be accessible anymore.

Here is the method:

        def delete_all_users_selected_messages(message_ids, user_id, parent_id)
          Message.where(:id => message_ids, :sender_id => user_id).update_all(:sender_status => 1)
          Message.where(:id => message_ids, :recipient_id => user_id).update_all(:recipient_status => 1)
          Message.delete_all(:sender_status => 1, :recipient_status => 1, :parent_id => parent_id).where("id != ?", parent_id)
        end

It's quite obvious what I'm trying to do. I need to have the parent ignored. So where the primary key is equal to the parent_id means that row is a parent (normally the parent_id is nil but I needed it set to the primary keys value for some other reason, long story and not important). Anyway is there an SQL statement I can add on to the end of the last line in tat method? To make sure it only deletes messages where the id of the row is not equal to the parent_id?

I can arrange for the parent_id row to never be permitted for deletion unless the actual thread (MessageThreads table that references the messages tables conversations) is deleted.

Any way how can I make it so this parent row is ignored when that delete_all method is run?

Kind regards

Upvotes: 19

Views: 12641

Answers (4)

LondonGuy
LondonGuy

Reputation: 11098

This worked for me in the end.

Message.where('id != ? AND parent_id = ?', parent_id, parent_id).where(:sender_status => 1, :recipient_status => 1).delete_all

Basically returns all messages of that particular conversation except the one where id == parent_id. Whenever id == parent_id this means it's a parent message.

Upvotes: 2

igmarin
igmarin

Reputation: 443

Nowadays in Rails 4, you can do:

Model.where.not(attr: "something").delete_all

and

Model.where.not(attr: "something").destroy_all

And don't forget about difference:

  • destroy_all: The associated objects are destroyed alongside this object by calling their destroy method. Instantiates all the records and destroys them one at a time, so with a large dataset, this could be slow
  • delete_all: All associated objects are destroyed immediately without calling their destroy method. Callbacks are not called.

Upvotes: 30

Michael Durrant
Michael Durrant

Reputation: 96454

I would consider a slightly different approach and have the model that has the has_many relationship have :dependent => destroy with it, e.g.
User has_many :messages, :dependent => :destroy That way you don't get the 'dangling orphan record' issue you describe.

I would try and approach it this way rather than thinking 'all records except'.
I don't know if there is something I am not addressing but this is what comes to find for the issue described.

Upvotes: 1

James Chen
James Chen

Reputation: 10874

Why not use association from the parent record, something like this?

Message.where(:id => parent_id).first
  .children.where(:sender_status => 1, :recipient_status => 1)
  .delete_all

Upvotes: 2

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