Rails - Jan 2006 - Executing Ruby code that is inside a string

I would like to put Ruby code inside a string, between <%= %> tags, and 
have the code inside the tags executed when the string is displayed.  Is 
this possible?

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

Richard,

The <%= %> tag is for the express purpose of executing ruby code.   
You do not need to put it inside of a string, simply place the code  
in a <%= %> tag and it will be executed before the page is  
displayed.  The result of the code is what will be displayed on the  
page.

-Derrick

On Jan 25, 2006, at 8:57 AM, Richard Smith wrote:
> I would like to put Ruby code inside a string, between <%= %> tags,  
> and
> have the code inside the tags executed when the string is  
> displayed.  Is
> this possible?
>
> -- 
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

On Wed, 2006-01-25 at 09:04 -0500, Derrick Spell wrote:
> Richard,
> 
> The <%= %> tag is for the express purpose of executing ruby code.   
> You do not need to put it inside of a string, simply place the code  
> in a <%= %> tag and it will be executed before the page is  
> displayed.  The result of the code is what will be displayed on the  
> page.
----
along these lines...

how do you ''comment'' out these lines?

adding 

<!--
<% ruby code %>
-->

doesn''t work

Craig

<%# ruby code %>


Craig White wrote:
>On Wed, 2006-01-25 at 09:04 -0500, Derrick Spell wrote:
>  
>
>>Richard,
>>
>>The <%= %> tag is for the express purpose of executing ruby code.
>>You do not need to put it inside of a string, simply place the code  
>>in a <%= %> tag and it will be executed before the page is  
>>displayed.  The result of the code is what will be displayed on the  
>>page.
>>    
>>
>----
>along these lines...
>
>how do you ''comment'' out these lines?
>
>adding 
>
><!--
><% ruby code %>
>-->
>
>doesn''t work
>
>Craig
>
>_______________________________________________
>Rails mailing list
>Rails@lists.rubyonrails.org
>http://lists.rubyonrails.org/mailman/listinfo/rails
>
>
>
>  
>

Derrick Spell wrote:
> Richard,
> 
> The <%= %> tag is for the express purpose of executing ruby code.
> You do not need to put it inside of a string, simply place the code
> in a <%= %> tag and it will be executed before the page is
> displayed.  The result of the code is what will be displayed on the
> page.
> 
> -Derrick
Yes, that works for static parts of the .rhtml page.  But I have dynamic 
content on the page that is coming from the database.  For example, on 
my page I may have:


User profile: <%= @user.profile %>


The profile is a string that comes from the database.  It contains HTML 
formatting, but HTML alone is not enough to generate links on a Rails 
site - I need to the use the link_to() function to generate links.  For 
instance, the user''s profile may contain:


Hello this is my profile, and this is <%= link_to ''another
profile'',
:action=>''another''>.


But the code just gets displayed, not executed, because it is inside a 
string.

So, to repeat my original question, how can I execute Ruby code that is 
inside a string between <%= %> tags?

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

Richard Smith wrote:
> The profile is a string that comes from the database.  It contains HTML 
> formatting, but HTML alone is not enough to generate links on a Rails 
> site - I need to the use the link_to() function to generate links.
Uhm, no. <a href="/">Click</a> is a perfectly valid link
if you''ve
written it by hand or using the link_to helper. That''s what link_to 
does, you know; it returns HTML.
> So, to repeat my original question, how can I execute Ruby code that is 
> inside a string between <%= %> tags?
<%= eval(string) %>, but you need to reconsider you approach or pray 
that no one ever puts stuff like User.destroy_all in their profile.

You probably want to check out textilize or simple_format or any of the 
other text to HTML formats. Heck, letting the users input HTML should 
work - and since you assume they know Rails code to begin with, 
expecting them to know HTML isn''t unrealistic.

-- 
Jakob Skjerning - http://mentalized.net

Jakob Skjerning wrote:
> Richard Smith wrote:
>> The profile is a string that comes from the database.  It contains 
>> HTML formatting, but HTML alone is not enough to generate links on a 
>> Rails site - I need to the use the link_to() function to generate
links.
> 
> Uhm, no. <a href="/">Click</a> is a perfectly valid
link if you''ve
> written it by hand or using the link_to helper. That''s what
link_to
> does, you know; it returns HTML.
But <a href="/profile/show/3"> is more information than the user
might
have to hand, or should really be expected to know.  Besides, 
hard-coding it means that you can''t change routing, ever, or all your 
links break.
> <%= eval(string) %>, but you need to reconsider you approach or pray 
> that no one ever puts stuff like User.destroy_all in their profile.
No need for that.  Actually, it won''t work for ERb text.
> You probably want to check out textilize or simple_format or any of the 
> other text to HTML formats. Heck, letting the users input HTML should 
> work - and since you assume they know Rails code to begin with, 
> expecting them to know HTML isn''t unrealistic.
Basically, what Richard wants is to use ERb in the database.  This can 
be done thus (untested):
   <%= output = ''''
	ERb.new(@user.profile, nil, nil, "output").result binding
	output %>

Check here:
http://www.ruby-doc.org/stdlib/libdoc/erb/rdoc/index.html
And look at the safe_level option while you''re at it - it''s
bound to
come in handy.

-- 
Alex

> No need for that.  Actually, it won''t work for ERb text.
<% User.destroy_all %>

Works in a view...

You should check out liquid:

http://home.leetsoft.com/liquid/


Jules

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

On 1/25/06, Alex Young <alex@blackkettle.org>
wrote:
> Jakob Skjerning wrote:
> > Richard Smith wrote:
> >> The profile is a string that comes from the database.  It contains
> >> HTML formatting, but HTML alone is not enough to generate links on
a
> >> Rails site - I need to the use the link_to() function to generate
links.
> >
> > Uhm, no. <a href="/">Click</a> is a perfectly
valid link if you''ve
> > written it by hand or using the link_to helper. That''s what
link_to
> > does, you know; it returns HTML.
> But <a href="/profile/show/3"> is more information than the
user might
> have to hand, or should really be expected to know.  Besides,
> hard-coding it means that you can''t change routing, ever, or all
your
> links break.
>
> > <%= eval(string) %>, but you need to reconsider you approach or
pray
> > that no one ever puts stuff like User.destroy_all in their profile.
> No need for that.  Actually, it won''t work for ERb text.
Why on earth wouldn''t it work?

Joe

Jules Jacobs wrote:
>> No need for that.  Actually, it won''t work for ERb text.
> 
> <% User.destroy_all %>
> 
> Works in a view...
Yeah, but neither:

   <%= eval(''This is my <%= link_to "other profile",
:action => "show",
       :id => @user.profiles.shift %>'') %>
nor
   <%= eval(''foo bar &amp; flibble <% User.destroy_all
%>'') %>

would, making the eval() suggestion completely useless in the first 
place, which is what I meant.

I know about liquid.  I follow the php-savant school of thought when it 
comes to template languages, although I feel an awful lot less violently 
sick towards liquid than towards smarty.

-- 
Alex

Joe Van Dyk wrote:
> On 1/25/06, Alex Young <alex@blackkettle.org> wrote:
>> Jakob Skjerning wrote:
>>> Richard Smith wrote:
>>> <%= eval(string) %>, but you need to reconsider you approach
or pray
>>> that no one ever puts stuff like User.destroy_all in their profile.
>> No need for that.  Actually, it won''t work for ERb text.
> 
> Why on earth wouldn''t it work?
Unless I''ve misread, the OP has ERb in the database, and wants to use 
the link_to function within the context of the database templates.  You 
can''t just eval() an ERb template, it needs to go through the template 
engine.

-- 
Alex

On 1/25/06, Alex Young <alex@blackkettle.org>
wrote:
> Joe Van Dyk wrote:
> > On 1/25/06, Alex Young <alex@blackkettle.org> wrote:
> >> Jakob Skjerning wrote:
> >>> Richard Smith wrote:
> >>> <%= eval(string) %>, but you need to reconsider you
approach or pray
> >>> that no one ever puts stuff like User.destroy_all in their
profile.
> >> No need for that.  Actually, it won''t work for ERb text.
> >
> > Why on earth wouldn''t it work?
> Unless I''ve misread, the OP has ERb in the database, and wants to
use
> the link_to function within the context of the database templates.  You
> can''t just eval() an ERb template, it needs to go through the
template
> engine.
Yes, but if a ERb template has User.destroy_all in it, bye bye data.

I think I misread your post anyways.