Index: openacs-4/packages/acs-content-repository/www/doc/guide/storage.adp =================================================================== RCS file: /usr/local/cvsroot/openacs-4/packages/acs-content-repository/www/doc/guide/storage.adp,v diff -u -r1.2.2.1 -r1.2.2.2 --- openacs-4/packages/acs-content-repository/www/doc/guide/storage.adp 20 Aug 2015 17:19:50 -0000 1.2.2.1 +++ openacs-4/packages/acs-content-repository/www/doc/guide/storage.adp 25 Aug 2015 18:02:05 -0000 1.2.2.2 @@ -2,18 +2,23 @@ {/doc/acs-content-repository {Content Repository}} {} - - -

Storing Data in the Content Repository

This document provides an introduction to using the content +

Storing Data in the Content Repository

+

This document provides an introduction to using the content repository for storing data (binary or text files) and associated attributes. It describes how to store user portraits as an -example.

Define an Item Type

The first step towards using the content repository is to define +example.

+

Define an Item Type

+

The first step towards using the content repository is to define one or more content types for the data you wish to -manage.

The basic content item includes the following attributes:

+

Most types of content require additional attributes. For a photo, we probably also want to store the pixel width and height at -the very least:

+the very least:

+
   create table images (
     image_id       integer
                    constraint images_image_id_fk
@@ -23,8 +28,10 @@
     width          integer,
     height         integer
   );
-
Content types are nothing more than standard ACS Objects that
-inherit from content_revision:
+

+
Content types are nothing more than standard ACS Objects that
+inherit from content_revision:

+
 begin
 
  acs_object_type.create_type (
@@ -56,17 +63,22 @@
 end;
 /
 show errors
-
Note that content types always extend content_revision,
+
+

Note that content types always extend content_revision, rather than content_item. This is because we want to store multiple revisions of both the actual data (in this case the image) as well as associated attributes (the width and height of the image -may vary among revisions).

Define a Relationship to a Target Object

The content repository implements a flexible mechanism for +may vary among revisions).

+

Define a Relationship to a Target Object

+

The content repository implements a flexible mechanism for organizing data in a hierarchical fashion in a manner similar to a file system. This would be useful if we ever decided to allow each user to manage an entire personal photo gallery rather than a -single portrait.

In the simple case where each user is allowed a single portrait, +single portrait.

+

In the simple case where each user is allowed a single portrait, we can simply define a relationship between user and image as ACS -Objects:

+Objects:

+
   acs_rel_type.create_role('user');
   acs_rel_type.create_role('portrait');
 
@@ -81,13 +93,17 @@
      min_n_rels_two => 0,
      max_n_rels_two => 1
   );
-
Note that the user object is related to a
+
+

Note that the user object is related to a content_item object rather than an image object directly. Each image object represents only a single revision of a portrait. Revisions always exist in the context of an -item.

Store Objects

Now we have defined both a content type and relationship type, +item.

+

Store Objects

+

Now we have defined both a content type and relationship type, we can start storing portraits. The DML for processing a new -portrait upload form would look like this:

+portrait upload form would look like this:

+
   begin transaction
     :item_id := content_item.new(:name, :item_id, sysdate, NULL,                           '[ns_conn peeraddr]'); 
     # maybe have content_revision return the LOB locator so that it can
@@ -96,8 +112,12 @@
                                :item_id, :revision_id);
     blob_dml_file update cr_revisions set content = empty_blob() ...
     :rel_id := acs_rel.new(...)
-
Retrieve Objects
+

+
Retrieve Objects

+
   ns_ora write_blob ...
-
karlg\@arsdigita.com
Last Modified: $Id: storage.html,v 1.1.1.1 2001/03/13 22:59:26
+
+
+karlg\@arsdigita.com +

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

-