Re: How to Retrieve Session User?
Re: How to Retrieve Session User?
- Subject: Re: How to Retrieve Session User?
- From: Chuck Hill <email@hidden>
- Date: Wed, 4 Apr 2007 21:18:55 -0700
These are probably better questions for the Wonder list and for
someone who has actually used this class before. :-)
On Apr 4, 2007, at 9:07 PM, Peter Vandoros wrote:
Hi Chuck,
How will using ERXThreadStorage work in a non-Request-Response loop
thread like a separate thread spawned in a WOLongResponsePage?
A thread is a thread is a thread. You would need to set the values
in the thread you spawn from the worker thread that creates it.
IIRC, ERXThreadStorage can do this automatically.
And, how will it work using the new request handling in WO 5.4?
I don't know how or if it will affect it. There are aspects of the
changes that are not yet clear to me.
I am just interested because i need to achieve a similar thing as
Jean-François in that i need to know the "editing user".
It is a common need. I think his context idea is a good one.
ERXThreadStorage might be the easiest way to communicate the context.
Chuck
Chuck Hill wrote:
Hello Jean-François,
Take a look at ERXThreadStorage from Project Wonder. It is the
best solution to these sort of issues that I have seen.
Chuck
On Apr 4, 2007, at 8:47 PM, Jean-François Veillette wrote:
Fred, consider that having an EO access a Session objet can be
seen as a bad practice (by me at least).
That being said, an EO frequently need to access the current
logged in user, either for validation or for business processing.
Then you realize that the concept of a current logged in user is
part of your business model, not just a display helper object.
My first implementation at solving this problem was to subclass
EOEditingContext and add a currentUser access method (and ivar to
support it). This allowed all my business layer to have access
to it, and worked like a charm.
I was fortunate enough that my business layer was all in a single
framework, so it was easy to get control over all the business
objects and they where all aware of the 'special' subclass given
by the context() method.
At the application level, when a user logged in, I had to set the
defaultEditingContext.currentUser. When I needed a different
editing context (peer or child), I had a methods that copied the
additional information from a given context (the
defaultEditingContext). That way it was relatively painless to
keep the EO's context customized to the context of my business
logic.
You can see that this approach worked only because I had control
over all the business layer within a single framework. This
approach would be harder to implement in a context where you have
business objects from different frameworks that all need to
access the 'current user' without sharing a common
eoeditingcontext subclass implementation. So either you get a
generic editingContext subclass across all your business
frameworks, or you get into trouble and prefer another approach.
My second implementation at solving this problem was to set the
delegate of the EOEditingContext, that way I thought that It
would be easier to integrate with other business logic frameworks
since we all use the bare-default implementation of eof. It
worked, I set the delegate to a 'consultation' object, which is
more or less the equivalent of a what a WOSession is to the
interface layer.
But I'm still unconvinced, mainly because, one logic framework
might impose a different delegate that implement real
eoeditingcontext.delegate methods. Abusing the delegate
responsibilities will bites me on the long run, I have to find
another solution.
My next implementation at solving this problem will turn around a
common 'context' class that will have static methods to return
the current 'consultation' object given an EO (internally using
the eo.editingContext() has a key to map a consultation object).
Draft implementation :
public class Context {
HashMap contextHashMap;
public static Object context(Object ec) { return
contextHashMap.get(ec); }
public static void setContextForKey(Object ctx, Object key)
{ contextHashMap.put(key, ctx); }
}
Then somewhere early in Session constructor ... and/or anywhere I
create a new EOEditingContext I would do the same :
Context.setContextForKey(new
ConsultationObjectThatHoldMyBusinessLayerContextInformation(),
defaultEditingContext);
This is crappy code (we need a memory friendly implementation in
order to ease garbage collection of our context and key objects),
but you get the idea.
These are 2 working solutions (see my 2 first attempts at solving
this problem), so it is possible to solve it.
With so many brilliant WO developer around you will get a
solution that fits your mindset and your needs.
ps: KVC is the wrong tools for what you want to achieve.
- jfv
Le 07-04-04 à 21:09, Ken Anderson a écrit :
Fred,
I would verify that the session your setting the user on is the
same session your asking for the user. As Chuck mentioned
earlier, it's possible that you're creating sessions without
realizing it.
Ken
On Apr 4, 2007, at 8:41 PM, Fred Shurtleff wrote:
It's a typo - really 2 lines.
// set the session.user ((Session) session()).takeValueForKey
(user, "user");
Chuck Hill wrote:
On Apr 4, 2007, at 5:34 PM, Fred Shurtleff wrote:
Gino, Mark, Chuck, Mike,
I have tried all of your 'best practice' suggestions (not
Chuck's yet), and STILL have no luck. To recap, this is my
setup:
Session.java (declare a user)-
protected EOEnterpriseObject user;
Main.java (fetch/authenticate, & set the user in session)-
// fetch the user
EOEnterpriseObject user =
EOUtilities.objectMatchingKeyAndValue(session
().defaultEditingContext(), "User", "name", username);
// set the session.user ((Session) session
()).takeValueForKey(user, "user");
Typo or is it really commented out?
Post.java (get the user for inserting transaction)=
EOEnterpriseObject user = (EOEnterpriseObject) ((Session)
session()).valueForKey("user");
At this point (using the debug mode) the user is null!! This
seems so... basic, yet I cannot see the problem. So if you
see something awry, please shout again.
It is sort of like a magic show. If I put something in a box,
and then later open the box and the thing is not in there, how
did this happen? Answer: it is not the same box. Try this:
// fetch the user
EOEnterpriseObject user =
EOUtilities.objectMatchingKeyAndValue(session
().defaultEditingContext(), "User", "name", username);
// set the session.user
((Session) session()).takeValueForKey(user, "user");
NSLog.out.appendln("Registered user in session " + session
().sessionID());
Post.java (get the user for inserting transaction)=
EOEnterpriseObject user = (EOEnterpriseObject) ((Session)
session()).valueForKey("user");
NSLog.out.appendln("Retrieved user from session " + session
().sessionID());
Now, are the IDs the same or not? If not, check your HTML for
malformed HTML. On Mac? Use the iCab browser for its easy
HTML validation.
Chuck
Now what I think Chuck & Mike is saying is the above approach
is 'taking a short cut' so-to-speak(using built-in KVC settor/
gettors), and is lacking for reasons mentioned. A better
practice is to code explicit java methods to message (get/
set) objects - a la OO Programming style.
I appreciate all your help & suggestions - Fred
Chuck Hill wrote:
Adding onto Mark's comments... KVC is for when you can't
use statically compiled Java. Using KVC instead of
statically compiled Java:
- reduces the chance of having the compiler catch your mistakes
- makes the code harder to read
- makes it harder to make naming changes
- makes you a bad person ;-)
In your session you should have:
private User loggedInUser;
public void setUser(User user) {
loggedInUser = user;
}
public User user() {
return loggedInUser;
}
And your code sample should read:
// set the session user
((Session)session()).setUser(user);
...
EOEnterpriseObject user = ((Session)session()).user();
And if it still evaluates to null, then your code is
probably creating more sessions than you realize.
Chuck
On Apr 4, 2007, at 3:58 PM, Mark Morris wrote:
Hi Fred,
KVC is certainly an integral part of WO, but much of that
is a bit behind the scenes. For instance, if you create
the user() and setUser() methods in your Session class,
WO's KVC implementation is what lets you bind session.user
to a WOString in a component. So you get the advantages,
while still getting the benefits of proper methods that
Mike was mentioning (such as some compiler error checking,
easier maintainability/internal documentation, and the
ability to put some logic in the accessor methods).
Regards,
Mark
On Apr 4, 2007, at 5:22 PM, Fred Shurtleff wrote:
Chuck,
I would welcome your comments on my KVC usage.
I was actually surprised by Mike's statement re: KVC
'funnybusiness' as I was led to believe from my readings
that KVC was a very integral part of WO. And the KVC
concept seems very straight-forward to me - what can be
simpler than takeValueForKey( value, key)? Also this is
the technique I have learned from a number of tutorials.
But then I am unable to put/get a user into the session -
so there must be something I am missing. Actually I have
tried so many ways to retrieve the user, I now think I
never got the user into the session to begin with. :-)
Chuck Hill wrote:
Listen to Mike. I was just about to write and make the
same complaint of your code. Abusing KVC is NOT your
friend.
Chuck
On Apr 4, 2007, at 1:45 PM, Mike Schrag wrote:
PERSONALLY, I'd stop all this KVC funnybusiness. It has
its place and it's really powerful, but you're making
your life way obnoxious. Let Java do its job and just
call methods on things -- there are LOTS of benefits of
this. Define a proper user field on your Session class
and do setUser(..) and user() to retrieve it.
On Apr 4, 2007, at 4:40 PM, Fred Shurtleff wrote:
Mark - I understand where you are coming from, and did
try your suggestion. But I still am NOT getting a user
EO instance (I get null per the debugger).
Actually I checked the WO docs and both valueForKeyPath
AND valueForKey are valid methods of the Session class.
Problem is what is the correct syntax. The docs say
object.valueForKey(string), and your suggestion
provided the object part (ie session()) (I also tried
your input + valueForKeyPath but Eclipse complained
about 'no such key = session')
So I still am at a loss on how to retrieve a user EO
from the session. :-(
But thanks for your help/input!
Mark Morris wrote:
Hi Fred,
On Apr 4, 2007, at 3:10 PM, Fred Shurtleff wrote:
Hello,
I have a basic question on how to access the logged
in user for later use in updates. After
authenticating a user I enter him into the session,
but when I later try to retrieve this user in another
page, it fails(returns null).
So in my main page I record the user as follows:
if (_password.equals(password))
{ EOEnterpriseObject user =
EOUtilities.objectMatchingKeyAndValue(session
().defaultEditingContext(), "User", "name", username);
// set the
session.user session
().takeValueForKey(user, "user");
And on another page to add a new transaction which
needs the user relation attribute(as a foreign key):
EOEnterpriseObject user = (EOEnterpriseObject)
valueForKeyPath("session.user"); // user evals to
null???
Try changing this to:
EOEnterpriseObject user = (EOEnterpriseObject)
session().valueForKey("user");
valueForKeyPath is useful, but I don't think it can do
what you're asking of it here.
purchase.addObjectToBothSidesOfRelationshipWithKey
(user, "user");
The save fails because user is a required attribute.
And I'm not sure if I am not properly storing the
user in the session, or not properly retrieving the
user from the session.
Can anyone see what I am doing wrong or suggest
another approach?
TIA
Personally, I usually make currentUser an actual
variable in Session. (Private, with public accessor
methods, of course! ;-)
Regards,
Mark
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