Ladislav Slezak write:
> On 11.1.2010 10:24, Josef Reidinger wrote:
> [...]
> > why use it? smart to_xml and to_json so you don't need to define own method
> > unless
> > you have hash with problematic keys (see time model for example how to
> > solve it)
> > validations which checks attributes before save same behavior as
> > ActiveRecord and
> > ActiveResource
>
> I have added some validations to the repository model in the REST service.
> It's easy and it's well readable, e.g.:
>
> validates_inclusion_of :priority, :in => 0..200
>
> sets valid range for @priority attribute to 0-200.
>
> But I'd like to improve error reporting to the client when validation fails
> in save().
>
> An ActiveModel object has errors() method which returns data about the failed
> validations. It's even possible to convert them to XML using to_xml.
>
> And here is the problem: to_xml returns invalid data which cannot
> be parsed:
>
> >> r = Repository.new 'oss', 'oss', true
> => #<Repository:0x7fbd70deda70 @url="", @enabled=true, @keep_packages=false,
> @autorefresh=true, @name="oss", @id="oss", @priority=99>
> >> r.priority = 'sdfdsfd'
> => "sdfdsfd"
> >> r.valid?
> => false
> # this is correct, priority must be in range 0-200 and URL cannot be empty
> >> x = r.errors.to_xml
> => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<errors>\n <error:blank/>\n
> <error:inclusion/>\n</errors>\n"
> >> Hash.from_xml(x)
> REXML::UndefinedNamespaceException: Undefined prefix error found
>
> ^^^ The XML parsing fails here...
Hmm, it looks like bug.
>
>
> Another (probably related) problem is that the error list doesn't
> contain the failed attribute name:
>
> >> r.errors.full_messages
> => [:blank, :inclusion]
>
>
> After changing the validation statements to
>
> validates_inclusion_of :priority, :in => 0..200, :message => 'invalid
> priority'
> validates_presence_of :url, :message => 'empty URL'
>
> I get:
>
> >> r.errors.full_messages
> => ["empty URL", "invalid priority"]
>
> And to_xml produces parseable output:
>
> >> x = r.errors.to_xml
> => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<errors>\n <error>empty
> URL</error>\n <error>invalid priority</error>\n</errors>\n"
> >> Hash.from_xml(x)
> => {"errors"=>{"error"=>["empty URL", "invalid priority"]}}
>
>
> But defining error messages in backend is wrong, they should be translated by
> the frontend.
define error message in backend is good that it is well defined and could be
easily parsed in frontend.
>
> Moreover I don't want to add a custom error message to every validation,
> it could work automatically:
>
> - the REST service should return ActiveResource::Errors#to_xml result
> (http://api.rubyonrails.org/classes/ActiveRecord/Errors.html)
> - the client should
> - check ActiveResource::Validations#errors for errors
> (http://api.rubyonrails.org/classes/ActiveResource/Validations.html)
This work if you use save! on backend. Then it return 422 with correct xml and
it sets errors on frontend. If this doesn't work please report bug.
> - use error_messages_for() ViewHelper function for creating/displaying
> validation errors
> (http://api.rubyonrails.org/classes/ActionView/Helpers/ActiveRecordHelper.html#M001694)
>
I think that there is problem with localization
>
> Any idea how to make it work?
>
> Or do I need to define the same validations in the client model and provide
> translations there? (The advantage would be no communication between client
> and server in case of invalid input.)
My idea was, that you should use save! in backend. It reports error on frontend
and on frontend you can parse errors and create user friendly message for user.
Of course we could have some predefined helper, which takes common validation
string and translate it to default error message (not yet done, but it is easy
to do).
Josef
>
>
> --
>
> Best Regards
>
> Ladislav Slezák
> Yast Developer
> ------------------------------------------------------------------------
> SUSE LINUX, s.r.o. e-mail: [email protected]
> Lihovarská 1060/12 tel: +420 284 028 960
> 190 00 Prague 9 fax: +420 284 028 951
> Czech Republic http://www.suse.cz/
>
--
Josef Reidinger
YaST team
maintainer of perl-Bootloader, YaST2-Repair, parts of webyast
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