I'm not saying that 'store' shouldn't validate, it DEFINITELY should, what I
am saying is that 'store' shouldn't care about how the validation process
works. In Andy's original post, he said that 'store' would throw an
exception if 'validate' wasn't called first, and that's totally wrong. It
creates a very tight coupling between the 'validate' and 'store' methods,
which are relatively unrelated in terms of the public API of the object.
Here is a perfectly legit implementation of the 'store' method, using
validate, though it is definitely less effecient than it could be:
<cffunction name="store" ...>
<!--- arguments --->
<cfif structCount(validate())>
<cfthrow type="InvalidStateException" />
<cfelse>
<!--- do the store --->
</cfif>
</cffunction>
A better route is probably to have a private method that returns a bitmap or
something indicating which validation errors that both 'validate' and
'store' will call. Store will just look and see if it's non-zero, while
validate will unmap (is that the right term) the bits, and convert them to
textual error messages to return to the calling code. That also keeps the
messages (which are really part of the presentation layer) separate from the
logic.
barneyb
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Raymond Camden
> Sent: Monday, October 06, 2003 11:52 AM
> To: [EMAIL PROTECTED]
> Subject: RE: [CFCDev] Data validation
>
>
> This is an interesting view, Barney, more so because it seems wrong to
> me. Why would it not be the domain of "store" to also do a validate?
> Consider a Person CFC, which has an age property. The age must be a
> number greater or equal to zero, but less then 150 (or some such). Why
> would "store" want to assume that you passed it valid data? Sure it can
> validate (using <cfargument>) that the value was a number, but it can't
> validate that it's a "proper" number. I guess it comes down to - why do
> you assume the caller will send you proper data? You say validate is a
> tool to help the calling code - and I agree with that - but why can't it
> help other methods as well? I can certainly see the client calling
> validate() to ensure the data it wants to pass to store() is safe, but
> I'd assume store() would assume the user is always forgetful, and should
> therefore do the anal thing and validate() as well.
>
> ========================================================================
> ===
> Raymond Camden, ColdFusion Jedi Master for Mindseye, Inc
> (www.mindseye.com)
> Member of Team Macromedia (http://www.macromedia.com/go/teammacromedia)
>
> Email : [EMAIL PROTECTED]
> Blog : www.camdenfamily.com/morpheus/blog
> Yahoo IM : morpheus
>
> "My ally is the Force, and a powerful ally it is." - Yoda
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] On Behalf Of Barney Boisvert
> > Sent: Monday, October 06, 2003 11:52 AM
> > To: [EMAIL PROTECTED]
> > Subject: RE: [CFCDev] Data validation
> >
> >
> > I would highly recommend that your 'store' method does NOT
> > through an exception unless there is a problem. Having it
> > check to see if 'validate' was called is not it's job. It's
> > job is to merely disallow the operation if it can't proceed,
> > and whether 'validate' was called has no bearing on that.
> > 'validate' is a tool to help the calling code determine what
> > an exception means in a way that can help it be resolved.
> >
> > You want me to structure my code this way (which is perfectly legit):
> >
> > <cfset errors = myCFC.validate() />
> > <cfif structCount(errors) GT 0>
> > <!--- error display --->
> > <cfelse>
> > <cfset myCFC.store() />
> > </cfif>
> >
> > But I like to do it this way, since we have an exception
> > handling mechanism in CF. It just reads cleaner than a bunch
> > of CFIFs that are doing exception handling. And in this
> > case, it'll also save me from generating that error struct
> > unless I need it.
> >
> > <cftry>
> > <cfset myCFC.store() />
> > <cfcatch type="IllegalStateException">
> > <cfset errors = myCFC.validate() />
> > <!--- error display --->
> > </cfcatch>
> > </cftry>
> >
>
>
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