Re: How to Retrieve Session User?
Re: How to Retrieve Session User?
- Subject: Re: How to Retrieve Session User?
- From: David Avendasora <email@hidden>
- Date: Tue, 10 Apr 2007 06:07:35 -0500
See below
On Apr 6, 2007, at 11:31 AM, Fred Shurtleff wrote:
SEE BELOW
Art Isbell wrote:
On Apr 5, 2007, at 4:13 PM, Fred Shurtleff wrote:
Also I know what you are saying about the use of the primary key
use and EOF discouraging its explicit usage; but this does not
appear to be such a bad transgression in that it is not ever
displayed nor used as a user manipulated attribute.
How is it a form value then? Is it written to a hidden text
field?
The topicID value has to come from somewhere. Maybe it's a
foreign key in an object that your Java code already knows about.
In any event, it seems likely that you can refer to the Topic
object that topicID represents as a relationship value from a
"parent" object or in some way that avoids using the primary key
explicitly.
This is a 3 entity situation driving from parent entity(Forums) >
child/related entity(Topics) > final entity(Posts/Replys), and uses
the primary key to link/drill down thru these entities. The user
never sees/uses this primary key. Behind the scene each page has a
link bound to a DA key (?forumID = forumID;) where the component
class has a key retrieval method as follows:
public Integer forumID() {
NSDictionary primaryKey = EOUtilities.primaryKeyForObject
(forum.editingContext(), forum);
return (Integer) primaryKey.valueForKey("forumID");
Next the DA methods uses the passed key to fetch the related Topics
and stuff them into the response component as follows:
public WOActionResults topicsAction() {
WOComponent nextPage = pageWithName("ForumTopics");
Number forumID = request().numericFormValueForKey("forumID", new
NSNumberFormatter());
EOEnterpriseObject forum = EOUtilities.objectWithPrimaryKeyValue
(WOApplication.application().sharedEditingContext(), "Forum",
forumID);
Are you using a Direct Action so you can book-mark the "ForumTopics"
page? If so, I guess using the primary key as a URL parameter is a
correct-enough way to do it, but you also stated that the user never
sees/uses this key. I would suggest coming up with a more human-
readable, yet still-unique attribute and put that in the URL so a
user might have some clue as to where the URL was taking them by just
looking at it.
If you don't require the ForumTopics page to be bookmarkable, then I
would suggest not using a Direct Action. It is much easier to simply
pass the object between the pages instead of passing only a reference
that then requires another lookup.
WOComponent nextPage = pageWithName("ForumTopics");
nextPage.setForum(forum);
return nextPage;
in the ForumTopics component you would have:
public EOEnterpriseObject forum;
public void setForum(EOEnterpriseObject requestedForum) {
forum = requestedForum;
}
Number index = request().numericFormValueForKey
("displayBatchIndex", new NSNumberFormatter());
// set variables
nextPage.takeValueForKeyPath(forum,
"topicsDisplayGroup.masterObject");
if (index != null) nextPage.takeValueForKeyPath(index,
"topicsDisplayGroup.currentBatchIndex");
return nextPage;
As you can see there is a sharedEditingContext used I presume based
on the assumption that the Forums and Topics tables are not very
dynamic, and uses localized version of the shared context to
perform edits.
But the Topic OBJECT (not table - you are still thinking in terms of
the database) is changing ALL THE TIME. Every time a user submits a
Post/Reply, you must update the Topic OBJECT'S posts/replys() to-many
relationship. This doesn't have any impact on the Topic TABLE in the
database, but it does impact the Topic OBJECT. I don't think that
this is a proper use of a sharedEditingContext at all.
As far the questionable use of the primary key, it looks to me as
simply an example of using built-in WO methods to filter an EC
using primary keys - not so bad.
Re:EOSharedEditingContext it is 'crossed out' in the Eclipse IDE
and shows a context message indicating this is a deprecated
method. But then the code you see was written in 2002 for a demo
app in "WebObjects Developer's Guide"(SAMS Publisher).
Shared objects can be tricky to use correctly. Failure to do
so can result in deadlocks and other problems. The best
description I have found is at <http://developer.apple.com/
documentation/LegacyTechnologies/WebObjects/WebObjects_4.5/System/
Documentation/Developer/WebObjects/DeltaDoc/EOF.html#CBGCHAIA>.
It's a pretty quick read that can save much grief later.
Thanks for the link :-)
Aloha,
Art
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