New, form_for and automatically-determined values

I have something I’m calling “tag”, and it has a text field plus (among
other things) a field to hold the time of creation. My goal is to
present the user with a form asking for the text field, but to infer
(and save) the timestamp automatically.

Should I be doing something in my “view”, or somewhere else. And,
well, what is it that I’ll be doing there?

PS. I’m new to RoR, and I hope my subject line is reasonable, and that
this posting isn’t a bother to those who are used to working at a
higher level.

Dan.

Hi Dan,

dankelley wrote:

I have something I’m calling “tag”,

Depending on how you use it, this could cause you trouble. ‘tag’
already
has meaning within Rails, especially within the context of forms. You
might
want to use a different name, just to save yourself some hard learning.

and it has a text field plus (among other things)
a field to hold the time of creation. My goal is to
present the user with a form asking for the text field,
but to infer (and save) the timestamp automatically.

Check out ‘created_at’
(http://wiki.rubyonrails.org/rails/pages/MagicFieldNames). Does exactly
what you’re looking for.

PS. I’m new to RoR,

Welcome!

and I hope my subject line is reasonable, and that
this posting isn’t a bother to those who are used to
working at a higher level.

There are folks here at all levels. That’s one of the things that keeps
the
community thriving. Don’t worry about ‘bothering’ folks.

Best regards,
Bill

Bill’s advice is terrific, and it solves most of my problem. However,
I probably chose a bad example by using something for which there is
magic.

Suppose that additionally I want to save something else in the db entry
that arises after the webform has been submitted. (Example: my site
will have logged-in users, and I’d like to save is the “id” of the user
who has used the webform.) Is there a way I can tell RoR to run some
code, after the form has been submitted?

PS. I realize that I’m probably looking at this problem in an old
(non-MVC) way, set up by decades of programming within systems that
have less “magic” and that thus require more coding. But I’m pursuing
this on this thread in hopes that it helps others who are in the same
boat … although they may have started with PHP and not Fortran :slight_smile:

Hi Dan,

dankelley wrote:

I probably chose a bad example by using something
for which there is magic.

But wait!. There’s more !!! :slight_smile:

Suppose that additionally I want to save something else
in the db entry that arises after the webform has been
submitted. (Example: my site will have logged-in users,
and I’d like to save is the “id” of the user who has used
the webform.) Is there a way I can tell RoR to run some
code, after the form has been submitted?

Several. Easiest to start with is filters.

From the docs (at http://api.rubyonrails.org) on the
ActionController::Filters::ClassMethods module…

“Filters enable controllers to run shared pre and post processing code
for
its actions. These filters can be used to do authentication, caching, or
auditing before the intended action is performed. Or to do localization
or
output compression after the action has been performed. Filters have
access
to the request, response, and all the instance variables set by other
filters in the chain or by the action (in the case of after filters).”

If you’re new to the api documentation you’ll find the module doc links
in
the middle-left frame. The lower-left contains links by method into the
module docs. Poking around in the methods is time well spent.

Don’t worry if the beginning sections are a bit over your head re: OO
concepts and terminology. Skip to the ‘Filter chain ordering’ section.
You’re interested in the before_filter and after_filter methods. Google
‘rails after_filter’ for more, including sample code.

hth,
Bill

(replying to self, with solution that worked for me…)

I ended up doing something simple – I just tacked the code I wanted
into the “create” method of my controller. This might come back to
bite me later, but so far it seems a reasonable solution.

Thanks, Bill, for the several threads of advice you’ve given.

Dan.

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