Regular expressions slay me

Rails
1

I am furiously trying to find what I am looking for in Pickaxe book and
not finding it.

I’m getting some values back from a posted form and I need to get the
‘id’ number off the backend. The ‘String’ will always come back to me
as…

Some_name\r\n123

where 123 is actually the id number which I need to execute the find.
The reason they are coming back this way is from a composite
‘text_auto_complete_for’ methodology which is allowing users to pick by
name and I want the associated id column for an easy find.

But I can’t get to square one with irb…

irb(main):021:0> myvar = “Some_name\r\n123”
=> “Some_name\r\n123”
irb(main):022:0> show_regexp(myvar, /\w+/)
NoMethodError: undefined method `show_regexp’ for main:Object
from (irb):22
from :0

Please someone…

a. tell me what type of command I would need to pick the numbers off the
end

b. tell me why irb doesn’t do something so obviously in the Pickaxe
book.

Thanks

Craig

2

Craig W. wrote:

I am furiously trying to find what I am looking for in Pickaxe book and
not finding it.

I’m getting some values back from a posted form and I need to get the
‘id’ number off the backend. The ‘String’ will always come back to me
as…

Some_name\r\n123

So you actually have a multi-line string being returned…

3

On Wed, 2006-03-08 at 22:53 -0500, Brian V. Hughes wrote:

So you actually have a multi-line string being returned…

irb(main):022:0> show_regexp(myvar, /\w+/)
book.

apparently, a multi-line string is being returned…

Yes

Craig

4

On Mar 8, 2006, at 7:48 PM, Craig W. wrote:

where 123 is actually the id number which I need to execute the find.
NoMethodError: undefined method `show_regexp’ for main:Object
from (irb):22
from :0

Please someone…

a. tell me what type of command I would need to pick the numbers
off the
end

/(\d+)$/

Answer in $1

b. tell me why irb doesn’t do something so obviously in the Pickaxe
book.

Page 93 of the Pick Axe shows give this for show_regex…

def show_regexp(a, re)
if a =~ re
“#{$`}<<#{$&}>>#{$’}”
else
“no match”
end
end

Have you defined that method before using it?

–
– Tom M.

5

Ignore that last message. Stupid email client! :slight_smile:

Craig W. wrote:

I am furiously trying to find what I am looking for in Pickaxe book and
not finding it.

I’m getting some values back from a posted form and I need to get the
‘id’ number off the backend. The ‘String’ will always come back to me
as…

Some_name\r\n123

Right… where was I? Oh, yeah. The returned value is a multi-line
field. But that’s not going to be a problem in this case because getting
the second line is really quite simple.

NoMethodError: undefined method `show_regexp’ for main:Object
from (irb):22
from :0

You can’t use show_regexp like that unless you’ve recently defined it as
a stand alone method. That’s why irb is telling you it’s undefined.

Please someone…

a. tell me what type of command I would need to pick the numbers off the
end

Give this a try: id_num = “Some_name\r\n123”.split("\r\n")[1]

b. tell me why irb doesn’t do something so obviously in the Pickaxe
book.

I don’t really have an answer on that, but from a Ruby standpoint, I’d
say you were making an incorrect attempt at calling a method. I’ve never
looked at show_regexp, but I’d guess it’s a String or Regex object
method, so you would need to treat it as such, if you want to have it
return a usable value.

-Brian

6

Brian V. Hughes wrote:

Craig W. wrote:

Some_name\r\n123

a. tell me what type of command I would need to pick the numbers off the
end

Give this a try: id_num = “Some_name\r\n123”.split("\r\n")[1]

I’d make one quick ammendment to my statement above:

 id_num = "Some_name\r\n123".split("\r\n")[1].to_i

That way, you know you’re getting back a Fixnum value, not a string.

-Brian

7

Hi –

On Wed, 8 Mar 2006, Craig W. wrote:

The reason they are coming back this way is from a composite
from :0

Please someone…

a. tell me what type of command I would need to pick the numbers off the
end

If those are definitely the only numbers in the string, you could do:

numbers = myvar[/\d+/]

meaning: the substring of myvar that consists of one-or-more digits
(\d+).

If you need to specify the digits at the end of the entire string (as
opposed to any possible other digits), you would use an “anchor” in
the regular expression, to indicate end-of-string:

numbers = myvar[/\d+\Z/]

The \Z anchor actually means: end of string, give or take a trailing
\n. \z means absolute end of string. \Z is preferable if you’re not
sure whether there’s a trailing \n and don’t want to worry about it.

b. tell me why irb doesn’t do something so obviously in the Pickaxe
book.

I can’t put my finger on show_regexp in the Pickaxe but I think the
answer is that it’s defined there. It’s not part of Ruby; that’s why
irb doesn’t know about it :slight_smile:

David

–
David A. Black ([email protected])
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

“Ruby for Rails” chapters now available
from Manning Early Access Program! Ruby for Rails

8

I’m gonna have to take some time to digest this…interesting that you
come around with this now that I have all of the puzzle solved.

This one was a several week puzzle. It starts with aggregation fields,
using the aggregation for auto_complete and finally, I was able to get
the id # along for the ride because finding on aggregation fields can be
a problem. I can do it the ‘rails’ way, but I’ve been spoiled by Ezra’s
ez_where plug-in which tremendously simplify complex SQL finds. The only
limitation I have run into with Ezra’s ez_where plug-in is including a
series of concatenated columns in a postgres table and now I can finally
end run around that limitation (and I say limitation but I doubt that
what I am doing is commonly done with SQL finds).

Anyway, thanks and I’m going to investigate it.

Craig

9

On Wed, 2006-03-08 at 19:59 -0800, Tom M. wrote:

Some_name\r\n123
=> “Some_name\r\n123”

if a =~ re
“#{$`}<<#{$&}>>#{$’}”
else
“no match”
end
end

Have you defined that method before using it?

No - I’m looking at page 73 and I’m seeing the examples and thinking,
heck, they work there…

I hadn’t gotten to p. 93 yet

:wink:

Thanks…between the two answers, I can probably make it work but you
can understand my desire to use irb to test these things out so I don’t
have to bother the list.

Craig

10

On Wed, 2006-03-08 at 23:02 -0500, Brian V. Hughes wrote:

I’d make one quick ammendment to my statement above:

 id_num = "Some_name\r\n123".split("\r\n")[1].to_i

That way, you know you’re getting back a Fixnum value, not a string.

the first one slayed my dragon…I got the concept though thanks

Craig

11

Hi Craig, here is an alternative to doing something like that, this
relies
on this patch which I hope gets included:

Patch: http://dev.rubyonrails.org/ticket/3691

In the view, your typical auto_complete, note the hidden field for the
id,
and the javascript callback (after_update_element):

<%= text_field_tag ‘client’, ‘’ %>
<%= hidden_field ‘encounter’, ‘client_id’ %>

<%= auto_complete_field 'client', :url => {:controller => 'clients', :action => 'auto_complete_for_client'}, :after_update_element => 'auto_complete_on_select', :select => 'name' %>

Also in your view, in a script block. Here I use the DOM to grab the ID:

function auto_complete_on_select(element, selectedElement)
{
document.getElementById(‘encounter_client_id’).value =
selectedElement.childNodes.item(0).innerHTML;
}

And finally, the partial for the autocomplete:

    <% for client in @clients do -%>
  • <%= client.id -%>
    <%= h client.name %>
    • <% end -%>

The informal hides the ID element from view and the javascript uses that
to
populate the hidden field, so that your ID is available when you submit
the
form.

To answer your original question:

irb(main):019:0> var = “Some_name\r\n123”
=> “Some_name\r\n123”
irb(main):020:0> var =~ /([[:digit:]+])/m
=> 11

For the show_regexp, do you have the function defined? Its not a ruby
function.

def show_regexp(a, re)
if a =~ re
“#{$`}<<#{$&}>>#{$'}”
else
“no match”
end
end

Bob S.
http://www.railtie.net/

12

On 3/8/06, Craig W. [email protected] wrote:

I hope that you appreciate that I wanted to work through the regular
expressions and figured irb was the lab to do that but there are times
when I don’t have what I need in irb at my disposal.

On a related note, “Mastering Regular Expressions” by Jeffrey Friedl
is easily one of the best software-related books I’ve ever read.

– James

13

On Thu, 2006-03-09 at 23:25 -0600, James L. wrote:

On 3/8/06, Craig W. [email protected] wrote:

I hope that you appreciate that I wanted to work through the regular
expressions and figured irb was the lab to do that but there are times
when I don’t have what I need in irb at my disposal.

On a related note, “Mastering Regular Expressions” by Jeffrey Friedl
is easily one of the best software-related books I’ve ever read.

Regular Expression Pocket Reference, 2nd Edition [Book]

thanks, I’ll file that in books that I should read but don’t want to
read (like Dave’s subversion book and many others) because I don’t use
it enough to want to be expert at it…at most, it’s a once in a great
while thing. My issue was getting the ability to test within irb and it
was pointed out to me that somewhere earlier in the chapter, I
undoubtedly missed a ‘method’ that made the samples throughout the
chapter work and I clearly wasn’t working the book in a linear fashion.

Craig

14

Also check out one of the best interactive regexp gui tools…
http://www.weitz.de/regex-coach/
-bakki

15

On Wed, 2006-03-08 at 20:04 -0800, [email protected] wrote:

=> “Some_name\r\n123”
If those are definitely the only numbers in the string, you could do:
numbers = myvar[/\d+\Z/]
irb doesn’t know about it :slight_smile:

thanks David - this actually gave me a clearer idea of the methodology.

I probably have to start digging in at the beginning of the chapter of
the pickaxe book to figure out why he’s giving examples that won’t work
in irb - and as you and others have pointed out, what I assumed to be a
ruby command…show_regexp is not a ruby command at all and would have
to be some kind of method that I hadn’t created. I did read it once
linearly and try to use it as reference but of course not in a linear
fashion and this time it frustrated me.

I hope that you appreciate that I wanted to work through the regular
expressions and figured irb was the lab to do that but there are times
when I don’t have what I need in irb at my disposal.

Craig

16

You can also check out

hth

Thibaut