Creating Content Revisions

At a basic level, creating a new revision of a content item involves the following steps:

1. Insert a row in the acs_objects table to create the object.
2. Insert a corresponding row in the cr_revisions table with the basic attributes for the revision.
3. Write the content data into the content BLOB column of the cr_revisions table.
4. Insert a corresponding row into the attribute table of each ancestor of the content type of the item. This is not applicable if the content type is Basic Item or an immediate subtype thereof.
5. Insert a corresponding row into the attribute table of the content type of the item. This is not applicable if the content type is Basic Item.

Use the Content Revision API to create a revision

Content revisions are initialized using the content_revision.new function. The only parameters required to create the revision are a title, a content item ID, and some text:

revision_id := content_revision.new( 
    title   => 'A Revision',
    item_id => :item_id,
    text    => 'Once upon a time Goldilocks crossed the street.
                Here comes a car...uh oh!  The End'
);

The item_id parameter is ID of the content item with which the revision is associated.

The content_item.new function accepts a number of other optional parameters: description, mime_type, and publish_date. The standard creation_date, creation_user, and creation_ip should be specified for auditing purposes. Instead of the text parameter, this function can be called with a data parameter, in which data is a blob:

revision_id := content_revision.new(
    title         => 'A Revision',
    description   => 'A Description of a revision',
    mime_type     => 'text/html',
    publish_date  => to_date('Jan 22, 2000','Mon DD, YYYY'),
    item_id       => :item_id,
    data          => :blob_of_content,
    creation_date => sysdate,
    creation_user => :user_id,
    creation_ip   => :ip_address
);

Insert additional attributes

Given that there is no way (AFAIK) to pass variable parameters to a PL/SQL function, there is no way to make content_revision.new generic enough to support submission of the attributes for all different content types. This leaves you with three alternatives:

1. Call content_revision.new followed by manual DML statements to write data into the content BLOB and insert attributes.
2. Write a PL/SQL package for each of your content types, which encapsulates the above code.
3. Create revisions by inserting into the attribute view for each content type.

The last option is made possible by an instead of insert trigger on the attribute view for each content type. (An attribute view joins together the storage tables for the ancestors of each content type, including acs_objects and cr_revisions). Normally it is not possible to insert into a view. Oracle allows you to create an instead of trigger for a view, however, which intercepts the DML statement and allows you to execute an arbitrary block of PL/SQL instead. The code to create or replace the trigger is automatically generated and executed with each call to content_type.create_attribute. The trigger makes it possible to create complete revisions with a single insert statement:

insert into cr_revisionsx (
  item_id, revision_id, title
) values (
  18, 19, 'All About Revisions'
);

Because a special trigger is generated for each content type that includes insert statements for all inherited tables, revisions with extended attributes may be created in the same fashion:

insert into cr_imagesx (
  item_id, revision_id, title, height, width
) values (
  18, 19, 'A Nice Drawing', 300, 400
);

Inserting content via file or text upload

Selecting a live revision

The live revision of a content item can be obtained with the content_item.get_live_revision function:

live_revision_id := content_item.get_live_revision(
    item_id => :item_id
);

The item_id identifies the content item with which the revision is associated.

Likewise, the most recent revision of a content item can be obtained with the content_item.get_latest_revision function:

latest_revision_id := content_item.get_latest_revision(
    item_id => :item_id
);

Last Modified: $Id: revisions.html,v 1.1.1.1 2001/03/13 22:59:26 ben Exp $