Rails - Jul 2007 - How do I alter posted data before it is saved in a controller?

Hi everyone,

I''m still new to Ruby and Ruby on Rails.  I''ve worked with
CakePHP for
quite a while though, so I''m happy to see that most of what
I''ve
learned about CakePHP translates over (more or less,) in using Ruby on
Rails.

But I''m stuck.  After reading numerous tutorials I still can''t
find an
answer.  My question is (like the title suggests,) "How do I alter
posted data before it is saved in a controller?"

For example, say I have a simple blog program using Ruby on Rails.  I
understand how make a blog form (where one fills in a blog post...)
and then post (save) the blog post.  What I don''t understand how to do
in Ruby is... how does one alter a value from a View that has been
posted to a Controller?

Why would I want to do this?  Simple; what if I want to make a form
field all lowercase after it has been submitted by a user?  Does
anyone know of a method I need to be using to make this happen?  I''ve
been searching around the API (http://api.rubyonrails.org/) all
afternoon today... but still can''t figure out why I can''t
alter a
posted variable.  Thanks for any help.

Andy


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Use before_save filter in your model.

before_save :convert_to_lower

def convert_to_lower
#do you stuff here
self.title.downcase!
end

Kates

On 7/13/07, summea <summea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Hi everyone,
>
> I''m still new to Ruby and Ruby on Rails.  I''ve worked
with CakePHP for
> quite a while though, so I''m happy to see that most of what
I''ve
> learned about CakePHP translates over (more or less,) in using Ruby on
> Rails.
>
> But I''m stuck.  After reading numerous tutorials I still
can''t find an
> answer.  My question is (like the title suggests,) "How do I alter
> posted data before it is saved in a controller?"
>
> For example, say I have a simple blog program using Ruby on Rails.  I
> understand how make a blog form (where one fills in a blog post...)
> and then post (save) the blog post.  What I don''t understand how
to do
> in Ruby is... how does one alter a value from a View that has been
> posted to a Controller?
>
> Why would I want to do this?  Simple; what if I want to make a form
> field all lowercase after it has been submitted by a user?  Does
> anyone know of a method I need to be using to make this happen? 
I''ve
> been searching around the API (http://api.rubyonrails.org/) all
> afternoon today... but still can''t figure out why I can''t
alter a
> posted variable.  Thanks for any help.
>
> Andy
>
>
> >
>
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Thanks for the quick reply!

And I''m just making sure... but is this the "real" way to do
it?  (Not
a hack, etc.)
Thanks again,

Andy


On Jul 12, 10:55 pm, "Kates Gasis"
<katesga...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Use before_save filter in your model.
>
> before_save :convert_to_lower
>
> def convert_to_lower
> #do you stuff here
> self.title.downcase!
> end
>
> Kates
>
> On 7/13/07, summea <sum...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
>
> > Hi everyone,
>
> > I''m still new to Ruby and Ruby on Rails.  I''ve
worked with CakePHP for
> > quite a while though, so I''m happy to see that most of what
I''ve
> > learned about CakePHP translates over (more or less,) in using Ruby on
> > Rails.
>
> > But I''m stuck.  After reading numerous tutorials I still
can''t find an
> > answer.  My question is (like the title suggests,) "How do I
alter
> > posted data before it is saved in a controller?"
>
> > For example, say I have a simple blog program using Ruby on Rails.  I
> > understand how make a blog form (where one fills in a blog post...)
> > and then post (save) the blog post.  What I don''t understand
how to do
> > in Ruby is... how does one alter a value from a View that has been
> > posted to a Controller?
>
> > Why would I want to do this?  Simple; what if I want to make a form
> > field all lowercase after it has been submitted by a user?  Does
> > anyone know of a method I need to be using to make this happen? 
I''ve
> > been searching around the API (http://api.rubyonrails.org/) all
> > afternoon today... but still can''t figure out why I
can''t alter a
> > posted variable.  Thanks for any help.
>
> > Andy

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It is the real way.

I recommend you buy the "Agile Web Development with Rails" book to
speed
up your learning + understanding.

-- 
Posted via http://www.ruby-forum.com/.

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If the lower-casing of input from a web form is part of your business logic,
then it belongs in the model, thus the below method is correct.  If you
follow the MVC design pattern strictly, you would have as little logic in
your views and controllers as possible, pushing all logic back into the
models.

This makes it easier to re-use your logic.  Say for example that you have
developed another method to add posts, one that requires a new controller.
By pushing this logic into the model, you avoid having to duplicate the
lower-casing of your field.  Trivial I know, but it''s a good habit to
get
into.



Take a look at

http://weblog.jamisbuck.org/2006/10/18/skinny-controller-fat-model
http://www.therailsway.com/2007/6/1/railsconf-recap-skinny-controllers
http://www.therailsway.com/2007/1/15/assetsgraphed-part-3

These gentleman explain it much better than I ever could.

Good luck!

-Brian Hogan


On 7/13/07, summea <summea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Thanks for the quick reply!
>
> And I''m just making sure... but is this the "real" way
to do it?  (Not
> a hack, etc.)
> Thanks again,
>
> Andy
>
>
> On Jul 12, 10:55 pm, "Kates Gasis"
<katesga...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > Use before_save filter in your model.
> >
> > before_save :convert_to_lower
> >
> > def convert_to_lower
> > #do you stuff here
> > self.title.downcase!
> > end
> >
> > Kates
> >
> > On 7/13/07, summea
<sum...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> >
> >
> > > Hi everyone,
> >
> > > I''m still new to Ruby and Ruby on Rails.  I''ve
worked with CakePHP for
> > > quite a while though, so I''m happy to see that most of
what I''ve
> > > learned about CakePHP translates over (more or less,) in using
Ruby on
> > > Rails.
> >
> > > But I''m stuck.  After reading numerous tutorials I still
can''t find an
> > > answer.  My question is (like the title suggests,) "How do I
alter
> > > posted data before it is saved in a controller?"
> >
> > > For example, say I have a simple blog program using Ruby on
Rails.  I
> > > understand how make a blog form (where one fills in a blog
post...)
> > > and then post (save) the blog post.  What I don''t
understand how to do
> > > in Ruby is... how does one alter a value from a View that has
been
> > > posted to a Controller?
> >
> > > Why would I want to do this?  Simple; what if I want to make a
form
> > > field all lowercase after it has been submitted by a user?  Does
> > > anyone know of a method I need to be using to make this happen? 
I''ve
> > > been searching around the API (http://api.rubyonrails.org/) all
> > > afternoon today... but still can''t figure out why I
can''t alter a
> > > posted variable.  Thanks for any help.
> >
> > > Andy
>
>
> >
>
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if all you want to do is manipulate form or query data from the client
(not necessarily always model data), just modify the data in the
params hash

ex: title = params[:title].downcase

then do with it what you will.

however, if, as others have suggested, you want to manipulate the data
as part of your model''s business logic, the best place to do that is
in the model itself, as the previous example shows.

On 7/13/07, summea <summea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
> Thanks for the quick reply!
>
> And I''m just making sure... but is this the "real" way
to do it?  (Not
> a hack, etc.)
> Thanks again,
>
> Andy
>
>
> On Jul 12, 10:55 pm, "Kates Gasis"
<katesga...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > Use before_save filter in your model.
> >
> > before_save :convert_to_lower
> >
> > def convert_to_lower
> > #do you stuff here
> > self.title.downcase!
> > end
> >
> > Kates
> >
> > On 7/13/07, summea
<sum...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> >
> >
> > > Hi everyone,
> >
> > > I''m still new to Ruby and Ruby on Rails.  I''ve
worked with CakePHP for
> > > quite a while though, so I''m happy to see that most of
what I''ve
> > > learned about CakePHP translates over (more or less,) in using
Ruby on
> > > Rails.
> >
> > > But I''m stuck.  After reading numerous tutorials I still
can''t find an
> > > answer.  My question is (like the title suggests,) "How do I
alter
> > > posted data before it is saved in a controller?"
> >
> > > For example, say I have a simple blog program using Ruby on
Rails.  I
> > > understand how make a blog form (where one fills in a blog
post...)
> > > and then post (save) the blog post.  What I don''t
understand how to do
> > > in Ruby is... how does one alter a value from a View that has
been
> > > posted to a Controller?
> >
> > > Why would I want to do this?  Simple; what if I want to make a
form
> > > field all lowercase after it has been submitted by a user?  Does
> > > anyone know of a method I need to be using to make this happen? 
I''ve
> > > been searching around the API (http://api.rubyonrails.org/) all
> > > afternoon today... but still can''t figure out why I
can''t alter a
> > > posted variable.  Thanks for any help.
> >
> > > Andy
>
>
> >
>
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Andy -

all the form variables are available as part of the params hash;
depending on how your form is coded, either directly (eg
params[:title]) or nested under the key for the appropriate model (eg.
params[:post][:title]).

These are passed into your constructor when you make a new instance of
a class, prior to saving et, eg:

@post = Post.new(params[:post)
post.save

so, either, you can do as Chris said, to create a modified variable,
and then pass that into your new object. Or you can modify the object
directly:

@post = Post.new(params[:post])
@post.title.downcase!
post.save

or, you can as described above, use a filter in the _model_ to run
code as an ActiveRecord callback.

The latter is correct, as mentioned, if that''s part of the behaviour
of that object (eg: a particular field should ALWAYS be downcase). If
it''s specific to the controller, you can probably get away with doing
it in the controller, but it probably isn''t.

The PHP frameworks I''ve looked at tend to have slightly more bloated
controllers than Rails; you want to be aiming for a skinny,
logic-light controller, if possible. But sometimes this isn''t always
possible, and if you''re having trouble making it that way, consider a
refactoring later on down the line.


On 13/07/07, Chris Hall
<christopher.k.hall-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
> if all you want to do is manipulate form or query data from the client
> (not necessarily always model data), just modify the data in the
> params hash
>
> ex: title = params[:title].downcase
>
> then do with it what you will.
>
> however, if, as others have suggested, you want to manipulate the data
> as part of your model''s business logic, the best place to do that
is
> in the model itself, as the previous example shows.
>
> On 7/13/07, summea <summea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> >
> > Thanks for the quick reply!
> >
> > And I''m just making sure... but is this the "real"
way to do it?  (Not
> > a hack, etc.)
> > Thanks again,
> >
> > Andy
> >
> >
> > On Jul 12, 10:55 pm, "Kates Gasis"
<katesga...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > > Use before_save filter in your model.
> > >
> > > before_save :convert_to_lower
> > >
> > > def convert_to_lower
> > > #do you stuff here
> > > self.title.downcase!
> > > end
> > >
> > > Kates
> > >
> > > On 7/13/07, summea
<sum...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > >
> > >
> > >
> > > > Hi everyone,
> > >
> > > > I''m still new to Ruby and Ruby on Rails. 
I''ve worked with CakePHP for
> > > > quite a while though, so I''m happy to see that most
of what I''ve
> > > > learned about CakePHP translates over (more or less,) in
using Ruby on
> > > > Rails.
> > >
> > > > But I''m stuck.  After reading numerous tutorials I
still can''t find an
> > > > answer.  My question is (like the title suggests,) "How
do I alter
> > > > posted data before it is saved in a controller?"
> > >
> > > > For example, say I have a simple blog program using Ruby on
Rails.  I
> > > > understand how make a blog form (where one fills in a blog
post...)
> > > > and then post (save) the blog post.  What I don''t
understand how to do
> > > > in Ruby is... how does one alter a value from a View that
has been
> > > > posted to a Controller?
> > >
> > > > Why would I want to do this?  Simple; what if I want to make
a form
> > > > field all lowercase after it has been submitted by a user? 
Does
> > > > anyone know of a method I need to be using to make this
happen?  I''ve
> > > > been searching around the API (http://api.rubyonrails.org/)
all
> > > > afternoon today... but still can''t figure out why I
can''t alter a
> > > > posted variable.  Thanks for any help.
> > >
> > > > Andy
> >
> >
> > >
> >
>
> >
>
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