Rails - Feb 2007 - negate the regexp in validates_format_of

Railsters:

ActiveRecord''s validation system puts other database systems to shame.

However, the newbies might not know how to write a regexp that
excludes a match, instead of tests for it. Understand - I''m just
asking this question to help them. I have been using Regexps since
''grep'' on Xenix! But the newbies here might not know how to do
this:

  validates_format_of :field_must_break, :with => /\n/

  validates_format_of :field_must_not_break, :with => /^[^\n]$/

The second one fails with data that correctly have no \n linefeed in them.

How do I - I mean "they" - negate a regexp?

-- 
  Phlip
  http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!

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validates_format_of :field_must_not_break, :with => /[^\n]/

There you - I mean "they" go

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Keynan Pratt wrote:
>  validates_format_of :field_must_not_break, :with => /[^\n]/
That passes on the first non-\n character. /^[^\n]+$/ doesn''t work
either. (Trying for "all characters between start and end not \n".)

New question: Why don''t any variations of Regexp have a bulk negation
operator? Most applications can rely on !~.

When we can''t use that, or when we must negate a subset of a regexp,
the result is super-ugly. The contrapositive of /\n/ should be just as
clean-looking, right?

-- 
  Phlip
  http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!

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so you wanted this then?
validates_format_of :field_must_not_break, :with => /^[^\n]*$/


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Phlip wrote:
> New question: Why don''t any variations of Regexp have a bulk
negation
> operator? Most applications can rely on !~.
> 
> When we can''t use that, or when we must negate a subset of a
regexp,
> the result is super-ugly. The contrapositive of /\n/ should be just as
> clean-looking, right?
> 
dude thats not a regexp problem. its simple

if(not str.includes?("\n"))

done

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which I belive you can do with

validates_exclusion_of

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Keynan Pratt wrote:
> so you wanted this then?
> validates_format_of :field_must_not_break, :with => /^[^\n]*$/
assert_match /^[^\n]+$/, "kozmik\nbullfrog"

That assertion passes - we want it to fail.

Next, there are two questions afloat - how to validate (without
resorting to validate(),  on principle), and whether all regexp
libraries everywhere have a big gap.

You can''t pass a validating block to validates_exclusion_of; only a
proc to determine if the validation should take place. It gets passed
the model, so we could put the ''not str.includes?'' in there,
but
that''s much more code than simply using a validate().

And ''not str.includes?'' doesn''t answer the
philosophical question
about regexps!

-- 
  Phlip
  http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!

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Are you looking for a field with only one character [which can''t be a
newline]? ''Cause that''s what /^[^\n]$/ does. You might want to
add some
wildcardier metacharacters to include more possible characters than just
one.

Or you might just want to ask this question over and over.

Excuse me, "they" might want to. ;)

RSL

On 2/16/07, Phlip <phlip2005-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Railsters:
>
> ActiveRecord''s validation system puts other database systems to
shame.
>
> However, the newbies might not know how to write a regexp that
> excludes a match, instead of tests for it. Understand - I''m just
> asking this question to help them. I have been using Regexps since
> ''grep'' on Xenix! But the newbies here might not know how
to do this:
>
>   validates_format_of :field_must_break, :with => /\n/
>
>   validates_format_of :field_must_not_break, :with => /^[^\n]$/
>
> The second one fails with data that correctly have no \n linefeed in them.
>
> How do I - I mean "they" - negate a regexp?
>
> --
>   Phlip
>   http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!
>
> >
>
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Russell Norris wrote:
> Are you looking for a field with only one character [which can''t
be a
> newline]? ''Cause that''s what /^[^\n]$/ does. You might
want to add some
> wildcardier metacharacters to include more possible characters than just
> one.
Wrong.
> Or you might just want to ask this question over and over.
Wrong.

-- 
  Phlip
  http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!

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Um... That''s actually right. [About the friggin'' regex].

rsl@sneaky:~$ irb
irb(main):001:0> rx = /^a$/
=> /^a$/
irb(main):002:0> "test" =~ rx
=> nil # Doesn''t have an "a"
irb(main):003:0> "tast" =~ rx
=> nil # Has an "a" but has other characters as well
irb(main):004:0> "a" =~ rx
=> 0 # Surprise! It passes there because it has only "a"
irb(main):005:0> rx = /^[^\n]$/
=> /^[^\n]$/
irb(main):006:0> "\n" =~ rx
=> nil # Fails on returns, as expected
irb(main):007:0> "" =~ rx
=> nil # Fails on empty string
irb(main):008:0> "1" =~ rx
=> 0 # Passes because there''s only one character
irb(main):009:0> "11" =~ rx
=> nil # Fails because there''s more than one character

http://www.google.com/search?q=regular+expressions<http://www.google.com/search?q=regular+expressions&ie=utf-8&oe=utf-8&rls=com.ubuntu:en-US:official&client=firefox-a>much?

On 2/17/07, Phlip <phlip2005-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Russell Norris wrote:
>
> > Are you looking for a field with only one character [which
can''t be a
> > newline]? ''Cause that''s what /^[^\n]$/ does. You
might want to add some
> > wildcardier metacharacters to include more possible characters than
just
> > one.
>
> Wrong.
>
> > Or you might just want to ask this question over and over.
>
> Wrong.
>
> --
>   Phlip
>   http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!
>
> >
>
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On Feb 17, 2007, at 10:14 AM, Russell Norris wrote:
> Um... That''s actually right. [About the friggin'' regex].
Sorry, it''s not.
>
> rsl@sneaky:~$ irb
> irb(main):001:0> rx = /^a$/
> => /^a$/
> irb(main):002:0> "test" =~ rx
> => nil # Doesn''t have an "a"
> irb(main):003:0> "tast" =~ rx
> => nil # Has an "a" but has other characters as well
> irb(main):004:0> "a" =~ rx
> => 0 # Surprise! It passes there because it has only "a"
> irb(main):005:0> rx = /^[^\n]$/
> => /^[^\n]$/
> irb(main):006:0> "\n" =~ rx
> => nil # Fails on returns, as expected
> irb(main):007:0> "" =~ rx
> => nil # Fails on empty string
> irb(main):008:0> "1" =~ rx
> => 0 # Passes because there''s only one character
> irb(main):009:0> "11" =~ rx
> => nil # Fails because there''s more than one character
$ irb
 >> r=/^a$/
=> /^a$/
 >> s="this\nis\na\nlong\nmulti-line\nstring"
=> "this\nis\na\nlong\nmulti-line\nstring"
 >> puts s
this
is
a
long
multi-line
string
=> nil
 >> s =~ r
=> 8
 >> r2 = /^[^\n]$/
=> /^[^\n]$/
 >> s =~ r2
=> 8
 >> "what?\n!" =~ r2
=> 6

> http://www.google.com/search?q=regular+expressions much?
No, ''cause I don''t need to.. Do you
http://www.ruby-doc.org/docs/
ProgrammingRuby/html/language.html#UL ever?

(got your back Philip ;-)

-Rob
> On 2/17/07, Phlip <phlip2005-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
> Russell Norris wrote:
>
> > Are you looking for a field with only one character [which
can''t
> be a
> > newline]? ''Cause that''s what /^[^\n]$/ does. You
might want to
> add some
> > wildcardier metacharacters to include more possible characters  
> than just
> > one.
>
> Wrong.
>
> > Or you might just want to ask this question over and over.
>
> Wrong.
>
> --
>   Phlip
>   http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!
Rob Biedenharn		http://agileconsultingllc.com
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org



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Hi --

On Fri, 16 Feb 2007, Phlip wrote:
>
> Railsters:
>
> ActiveRecord''s validation system puts other database systems to
shame.
>
> However, the newbies might not know how to write a regexp that
> excludes a match, instead of tests for it. Understand - I''m just
> asking this question to help them. I have been using Regexps since
> ''grep'' on Xenix! But the newbies here might not know how
to do this:
>
>  validates_format_of :field_must_break, :with => /\n/
>
>  validates_format_of :field_must_not_break, :with => /^[^\n]$/
How about:

   /\A[^\n]+\z/


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

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Well, snap on my doodle! I was so busy hoping I could give Phlip a heaping
bowl of his own brand of snotty reply that I tripped on some of my own brand
of over-confidence. Crow meet plate, fork, and knife. [Again.]

I''m still trying to wrap my head around this. I think of
"a\nb" as a string
containing three characters, a, the newline character, and b. Oh, I think I
see... ^ and $ don''t match the end and beginning of a _string_ but the
end
and beginning of a _line_... Sigh. Goddangit. Rassin''
frassin''.

Oh well. Apologies to Phlip, I''m fully prepared for and deserving of
your
next snarky retort. [But not the one after that.]

RSL

On 2/17/07, Rob Biedenharn
<Rob-GBZH0y1GwQfnZcttdmLDtcI/UQi/AW5J@public.gmane.org>
wrote:
>
>
> On Feb 17, 2007, at 10:14 AM, Russell Norris wrote:
>
> Um... That''s actually right. [About the friggin'' regex].
>
>
> Sorry, it''s not.
>
>
> rsl@sneaky:~$ irb
> irb(main):001:0> rx = /^a$/
> => /^a$/
> irb(main):002:0> "test" =~ rx
> => nil # Doesn''t have an "a"
> irb(main):003:0> "tast" =~ rx
> => nil # Has an "a" but has other characters as well
> irb(main):004:0> "a" =~ rx
> => 0 # Surprise! It passes there because it has only "a"
> irb(main):005:0> rx = /^[^\n]$/
> => /^[^\n]$/
> irb(main):006:0> "\n" =~ rx
> => nil # Fails on returns, as expected
> irb(main):007:0> "" =~ rx
> => nil # Fails on empty string
> irb(main):008:0> "1" =~ rx
> => 0 # Passes because there''s only one character
> irb(main):009:0> "11" =~ rx
> => nil # Fails because there''s more than one character
>
>
> $ irb
> >> r=/^a$/
> => /^a$/
> >> s="this\nis\na\nlong\nmulti-line\nstring"
> => "this\nis\na\nlong\nmulti-line\nstring"
> >> puts s
> this
> is
> a
> long
> multi-line
> string
> => nil
> >> s =~ r
> => 8
> >> r2 = /^[^\n]$/
> => /^[^\n]$/
> >> s =~ r2
> => 8
> >> "what?\n!" =~ r2
> => 6
>
>
>
http://www.google.com/search?q=regular+expressions<http://www.google.com/search?q=regular+expressions&ie=utf-8&oe=utf-8&rls=com.ubuntu:en-US:official&client=firefox-a>much?
>
>
> No, ''cause I don''t need to.. Do you
> http://www.ruby-doc.org/docs/ProgrammingRuby/html/language.html#UL ever?
>
> (got your back Philip ;-)
>
> -Rob
>
> On 2/17/07, Phlip <phlip2005-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> >
> >
> > Russell Norris wrote:
> >
> > > Are you looking for a field with only one character [which
can''t be a
> > > newline]? ''Cause that''s what /^[^\n]$/ does.
You might want to add
> > some
> > > wildcardier metacharacters to include more possible characters
than
> > just
> > > one.
> >
> > Wrong.
> >
> > > Or you might just want to ask this question over and over.
> >
> > Wrong.
> >
> > --
> >   Phlip
> >   http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!
> >
>
> Rob Biedenharn http://agileconsultingllc.com
> Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org
>
>
>
> >
>
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Hi --

On Sat, 17 Feb 2007, Russell Norris wrote:
> I''m still trying to wrap my head around this. I think of
"a\nb" as a string
> containing three characters, a, the newline character, and b. Oh, I think I
> see... ^ and $ don''t match the end and beginning of a _string_ but
the end
> and beginning of a _line_...
That''s correct.  \A and \z match the absolute beginning and end of a
string. \Z matches the end of a string but discounting a final
newline, if present.


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

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