Best practise for setting default URL parameters in the controller

Rails
#1

I’ve been trying to set default URL parameters in the controller, which
will also be used within the view. This is what I’ve got:

@params = params

defaults = { :date_from => ‘21/1/21014’, :date_to => ‘21/2/21014’,
:data=>“Expense” }
if @params.any?
@params = defaults.merge(@params)
else
@params = defaults
end

… seems messy, and doesn’t work :frowning: When params are present it still
uses
the default params. Not sure where it’s going wrong and search on google
yields many varieties. I know using default values in methods is
something
that I will repeat again so I was wondering what the best practise is
for
handling this. Thanks

#2

On 2 February 2014 06:22, Bizt [email protected] wrote:

@params = defaults
end

… seems messy, and doesn’t work :frowning: When params are present it still uses
the default params.

That is likely because it should be params not @params. I don’t think
you need the .any? test either, just let it merge the empty hash into
defaults.

If you need to do this in more than one controller method then use a
before filter.

Colin

#3

On Sunday, February 2, 2014 6:22:43 AM UTC, Bizt wrote:

… seems messy, and doesn’t work :frowning: When params are present it still uses the
default params. Not sure where it’s going wrong and search on google yields many
varieties. I know using default values in methods is something that I will repeat
again so I was wondering what the best practise is for handling this. Thanks

It doesn’t work because @params isn’t where params are stored. Params is
never empty (at a minimum :controller and :action are set) so you can
get rid of the else

You could update params in place , ie params.merge!(…).

Personally I wouldn’t do this. I’d be more likely to have a controller
method called something like get_date_range that would get the dates
from params that would do things like parse the strings into actual
dates and/or replace missing params with defaults.

Fred

#4

On Sunday, February 2, 2014 2:10:10 PM UTC, Colin L. wrote:

On 2 February 2014 13:57, Frederick C. [email protected] wrote:

…

You could update params in place , ie params.merge!(…).

Would that not use the value from defaults if it was already present in params?

I was assuming this was after checking that params didn’t have the
values in question, although if not you could use reverse_merge!

Fred

#5

On 2 February 2014 13:57, Frederick C. [email protected]
wrote:

…
You could update params in place , ie params.merge!(…).

Would that not use the value from defaults if it was already present in
params?

Personally I wouldn’t do this. I’d be more likely to have a controller method
called something like get_date_range that would get the dates from params that
would do things like parse the strings into actual dates and/or replace missing
params with defaults.

+1

Colin

#6

On Sun, Feb 2, 2014 at 5:02 AM, Colin L. [email protected] wrote:

That is likely because it should be params not @params.

But:

On 2 February 2014 06:22, Bizt [email protected] wrote:
…

This is what I’ve got:

@params = params

so @params should work the same as params. Not sure why he’s
bothering to copy it into an @-var, tho; maybe he wants access to it
in a view…

-Dave

–
Dave A., the T. Rex of Codosaurus LLC (codosaur.us),
freelance software developer, and creator of these sites:
PullRequestRoulette.com, blog.codosaur.us, & Dare2XL.com.

#7

On Sat, Feb 1, 2014 at 10:22 PM, Bizt [email protected] wrote:

I’ve been trying to set default URL parameters in the controller, which will
also be used within the view.

… so I was wondering what the best practise is for handling this.

Personally, I’d say “best practice” is “don’t do that” :slight_smile:

Instead of passing raw params to a view, build your model object
(or a service object) with them and pass that in. And if you need
defaults for missing attributes specified, the model/s.o. would be
a better place for them.

FWIW,

Hassan S. ------------------------ [email protected]
http://about.me/hassanschroeder
twitter: @hassan