Questions on acts_as_versioned

rubyonrails-talk
1

Thanks, Rick, for a great plugin. But one thgn leads to another, sort of like pulling at the thread in the willy jumper .... :slight_smile:

Three questions about acts_as_versioned; the second leads to other issues.

1. use of :sequence_name      is this the "order_by"? How is this going to be different from using the ':version_column' to order the      revisions.

2. Derived from (1).      If I have a ':version_column' set and I want optimistic locking as well, how do I do that?

3. I'm very unclear about using ':extend' or the "acts_as_versioned do ... end" construct.

Obviously I want to be able to reference any revision of the Page and any field or method:

... something     page.revision(rev_no).title = "Hello World".reverse     page.revision(rev_no).updated_at.suc === page.updated_at     display = page.revision(rev_no).render_content_to_html

If I wasn't using acts_as_versioned and was doing this with an explicit revision table I'd be writing thigns like

    class Page < ActiveRecord::Base        has_many :revisions        has_one :current_revision, :class_name => 'Revision', :order => 'rev DESC'

but I'd really like to DRY and not have to have a separate Revision model.

Any input or examples would be appreciated.

2

Thanks, Rick, for a great plugin. But one thgn leads to another, sort of like pulling at the thread in the willy jumper .... :slight_smile:

Three questions about acts_as_versioned; the second leads to other issues.

1. use of :sequence_name      is this the "order_by"? How is this going to be different from using the ':version_column' to order the      revisions.

This is some postgres thing, you can probably ignore it on other databases.

2. Derived from (1).      If I have a ':version_column' set and I want optimistic locking as well, how do I do that?

I think you just set the version column to lock_version. I've never used optimistic locking, so it may need some patches to get working correctly. Feel free to contribute if you do this.

3. I'm very unclear about using ':extend' or the "acts_as_versioned do ... end" construct.

It's similar to the :extend or block syntax of ActiveRecord associations, only it defines the methods on both the current class and the version class. For instance in Lighthouse (my Rails based ticket tracker app), Ticket comments are really just versions of the same ticket. But, I want the Ticket::Version model to quack like a Ticket, so I add a lot of methods and associations inside the acts_as_versioned block.

Obviously I want to be able to reference any revision of the Page and any field or method:

... something     page.revision(rev_no).title = "Hello World".reverse     page.revision(rev_no).updated_at.suc === page.updated_at     display = page.revision(rev_no).render_content_to_html

If I wasn't using acts_as_versioned and was doing this with an explicit revision table I'd be writing thigns like

    class Page < ActiveRecord::Base        has_many :revisions        has_one :current_revision, :class_name => 'Revision', :order => 'rev DESC'

but I'd really like to DRY and not have to have a separate Revision model.

Any input or examples would be appreciated.

acts_as_versioned creates another class for you. Check out the code (http://projects.wh.techno-weenie.net/browser/plugins/acts_as_versioned/lib/acts_as_versioned.rb), it sets up a versions association. You can define helper methods to access them by version # if you want. I suppose the current way would resemble:

@page.versions.find_by_version(234)