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setting page variables in onRequestStart
Author: Dominic Watson
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305992
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I agree with you for most app building. However, I was recently tasked
with building a pretty much flat site but where ColdFusion templating
would be really useful. For this simple app, I just setup
onRequestEnd.cfm to be the HTML template that outputted
#request.header# for various page specific header tags (javascript,
etc) and #request.body# for the main content. Each individual page
would then just savecontent to request.body and possibly
request.header to be outputted later in onRequestEnd.cfm. The request
scope was the logical place for these variables.
(I'm sure that onRequestEnd tactic must have been / is a common tactic
- not claiming originality!)
Dominic
--
Blog it up: http://fusion.dominicwatson.co.uk
Author: Dominic Watson
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305991
> Err, how is it a 'pseudo-scope"? The request scope is a real scope
> (don't give it any confidence issues!) just as much as Variables. And
> I'll repeat my earlier assertion - that maybe seeing Request.Foo will
> help it stand out compared to Variables.goo.
;) You mis-read me (and I express badly). For example, MG3 has introduced
the 'helpers' 'pseudo-scope'. With this, you put all your UDFs in a folder
called helpers and the app automagically places them all in a variable
called helpers. So then, in your cfms, or even your cfcs (yuck), you could
do:
<cfset result = helpers.stringUdfs.myStringFunction('foo')>
So here, 'helpers' is sort of a 'pseudo-scope'. Sure, it's just a structure
in the variables scope that has collections of udfs as its keys, but I think
the 'pseudo-scope' is a good term for it. This is what I was trying to
recreate for Richard - but I failed to calculate the inability to set
anything in the variables scope in application.cfc (the 'global' variables
scope outside of the cfc that is).
The request scope is absolutely fine. However, in this case, we were putting
the collection of udfs in the application scope and then wanting to create a
'pseudo-scope' for them to avoid verbosity. If that isn't possible, then the
best place for them is just to stay in the application scope (logically
where they belong):
<cfset result = application.helpers.myStringFunction('foo')>
But yeh, I completely agree that variables should sit in the scopes where
they belong - but I also like the idea of creating 'pseudo-scopes' if it
readable to do so ;)
Dominic
--
Blog it up: http://fusion.dominicwatson.co.uk
Author: Adam Haskell
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305989
My only problem with Request scope is that its available _everywhere_. I
understand you can be a good developer and not use it in your model or
elsewhere but I still dislike the request scope for that reason. Being a
person that is constantly working on framework and components to be used in
my company I cherish encapsulation and request scope spits in the face of
that. Sure Application and Session do too but they server a good purpose for
carrying state so I like them :) I do like your point about global
variables for the life of the request and being easy to differentiate
between those and page variables. I am with Dave though maybe Application or
Session would be a better place for that info? Just my 2 cents.
Also check out what Sean did with Application.cfc in fusebox very clever to
get around most of the limitations/issues with onRequest.
Adam Haskell
On Thu, May 22, 2008 at 4:17 PM, Raymond Camden <rcamden@gmail.com> wrote:
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Author: Dave Watts
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305984
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I read that article, and while I'm glad this turned out well for you, there
seems to be a serious misunderstanding in the article about how Java garbage
collection works in CF. The garbage collection doesn't run after every
request, by default - and you wouldn't want it to, either. Garbage
collection is an expensive operation. And just destroying the unwanted
references in onRequestEnd.cfm or the onRequestEnd method in Application.cfc
isn't going to change that - it just means that those variables will be
immediately eligible for garbage collection whenever it runs, as long as
those variables have no other references in the stack.
This isn't a memory leak. Java will eventually reclaim and reallocate that
memory.
That said, I'm not sure what's different about using Request variables in
this way, since they're just references like any other reference, and the
values stored in the heap should be destroyed by the garbage collector the
same way.
Finally, if you're creating truly global site variables, why not just use
the Application scope? That's what it's for, after all. You don't have to
worry about the silly locking issues like you did with CF 5 and earlier. Of
course, if things are working as they are, it's probably not worth changing
now.
Dave Watts, CTO, Fig Leaf Software
http://www.figleaf.com/
Fig Leaf Software provides the highest caliber vendor-authorized
instruction at our training centers in Washington DC, Atlanta,
Chicago, Baltimore, Northern Virginia, or on-site at your location.
Visit http://training.figleaf.com/ for more information!
Author: Dave Watts
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305983
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Yeah, that was really for the benefit of others, not for you personally.
That said, I've seen a lot of people use only Request variables in their
pages for this sort of thing.
Dave Watts, CTO, Fig Leaf Software
http://www.figleaf.com/
Fig Leaf Software provides the highest caliber vendor-authorized
instruction at our training centers in Washington DC, Atlanta,
Chicago, Baltimore, Northern Virginia, or on-site at your location.
Visit http://training.figleaf.com/ for more information!
Author: Dawson, Michael
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305960
Of course, but that was just an example.
m!ke
> In other words, do you use the variables scope at all on the "view"
> pages?
>
> Would you have used:
>
> <cfquery name="request.myQuery" ...> ?
If it's really a view page, in an MVC pattern, you wouldn't have any
CFQUERY tags in it.
Dave Watts, CTO, Fig Leaf Software
http://www.figleaf.com/
Author: Dave Watts
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305959
> In other words, do you use the variables scope at all on the "view"
> pages?
>
> Would you have used:
>
> <cfquery name="request.myQuery" ...> ?
If it's really a view page, in an MVC pattern, you wouldn't have any CFQUERY
tags in it.
Dave Watts, CTO, Fig Leaf Software
http://www.figleaf.com/
Fig Leaf Training: Adobe/Google/Paperthin Certified Partners
http://training.figleaf.com/
WebManiacs 2008: the ultimate conference for CF/Flex/AIR developers!
http://www.webmaniacsconference.com/
Author: Dawson, Michael
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305958
Just so I'm clear on this...
You are using the request scope for EVERY variable you set or ONLY the
global variables?
In other words, do you use the variables scope at all on the "view"
pages?
Would you have used:
<cfquery name="request.myQuery" ...> ?
m!ke
During our site rewrite, we opted to use the request scope over the
variables scope for all "view" (CFM) pages. We use onRequestStart() to
make sure certain global site variables are available in the request
scope.
Author: Adrian Moreno
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305954
During our site rewrite, we opted to use the request scope over the variables
scope for all "view" (CFM) pages. We use onRequestStart() to make sure certain
global site variables are available in the request scope.
After reading this article:
http://www.schierberl.com/cfblog/index.cfm/2006/10/16/memoryLeak_variablesScope
it turns out using the request scope everywhere was a great boon to the project.
One of our legacy applications uses Application.cfm, relies on the variables
scope and has major memory issues. If you look down in his Summary, #4 says
"Calling structClear(variables) in onRequestEnd.cfm will destroy unwanted
references tied to variables scope".
We added this code to one server in the middle of the day and watched the memory
on that server drop like a rock as soon as it deployed. We promoted it to the
rest of the servers and they've all been behaving much better ever since.
-- Adrian
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Author: Raymond Camden
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305953
Err, how is it a 'pseudo-scope"? The request scope is a real scope
(don't give it any confidence issues!) just as much as Variables. And
I'll repeat my earlier assertion - that maybe seeing Request.Foo will
help it stand out compared to Variables.goo.
On Thu, May 22, 2008 at 8:21 PM, Dominic Watson
<watson.dominic@googlemail.com> wrote:
----- Excess quoted text cut - see Original Post for more -----
--
===========================================================================
Raymond Camden, VP of Software Dev, Broadchoice
Email : ray@camdenfamily.com
Blog : www.coldfusionjedi.com
AOL IM : cfjedimaster
Keep up to date with the community: http://www.coldfusionbloggers.org
Author: Dominic Watson
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305938
> variables.viewState?
Ok Mr Pedant, pick up on the useless bit of the post damn you
:p
--
Blog it up: http://fusion.dominicwatson.co.uk
Author: Brian Kotek
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305936
variables.viewState?
On Thu, May 22, 2008 at 9:21 PM, Dominic Watson <
watson.dominic@googlemail.com> wrote:
----- Excess quoted text cut - see Original Post for more -----
Author: Dominic Watson
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305935
> I'd argue that variables he is setting on - every- page request should
> be segregated for normal page variables. If I see request.siteURL for
> example, it flags it as a variable that is always available, as
> opposed to just 'X' for example.
Sure, I'd be with you usually; but this is an entire 'pseudo scope'.
Would you argue for MG to use request.viewstate over just viewstate?
That wouldn't be so bad actually thinking about it; always bugged me a
little referencing viewstate without a scope lol
Dominic
--
Blog it up: http://fusion.dominicwatson.co.uk
Author: Raymond Camden
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305930
I'd argue that variables he is setting on - every- page request should
be segregated for normal page variables. If I see request.siteURL for
example, it flags it as a variable that is always available, as
opposed to just 'X' for example.
On Thu, May 22, 2008 at 5:15 PM, Dominic Watson
<watson.dominic@googlemail.com> wrote:
----- Excess quoted text cut - see Original Post for more -----
--
===========================================================================
Raymond Camden, VP of Software Dev, Broadchoice
Email : ray@camdenfamily.com
Blog : www.coldfusionjedi.com
AOL IM : cfjedimaster
Keep up to date with the community: http://www.coldfusionbloggers.org
Author: Dominic Watson
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305928
> Why not simply simply use the Request scope?
Verbosity. The idea he is working on is doing something similar to the
way MG3 creates the 'helper scope' for udfs. I think helpers.myUdf()
is preferable to request.helpers.myUdf() though its all good. Clearly
with MG, the helper/event/viewstate variables are setup outside of any
cfcs and I hadn't figured that in the sample code I came up with (I
still use application.cfm).
Dominic
--
Blog it up: http://fusion.dominicwatson.co.uk
Author: Richard White
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305924
thanks Raymond
i haven't yet looked into the request scope but will do now!
thanks again
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Author: Raymond Camden
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305923
Right, you can't do that. The variables scope in App.cfc isn't copied
to the template.
Unless you use onRequest. But that has some drawbacks as well.
Why not simply simply use the Request scope?
On Thu, May 22, 2008 at 3:10 PM, Richard White <richard@j7is.co.uk> wrote:
----- Excess quoted text cut - see Original Post for more -----
Author: Richard White
Short Link: http://www.houseoffusion.com/groups/cf-talk/thread.cfm/threadid:56505#305922
hi
is it possible to set page variables in the onRequestStart method of the
application.cfc?
if i enter the following code in the application.cfc:
<cfset variables.myVariable = "myVariable">
and the following code in my page:
<cfoutput>#myVariable#</cfoutput>
i get an error message when running a page saying myVariable is not defined
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