Rails - May 2010 - Newby Ruby question, how to I test to know if a method that returns true or false has done so?

I am testing for the existence of records on a database. If I use:

Mapper.exists?(product.id)

How do I test if the condition returned was true or false?

Thanks in advance.

Paul Thompson

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On May 18, 7:41 am, Paul Jonathan Thompson
<rails...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> I am testing for the existence of records on a database. If I use:
>
> Mapper.exists?(product.id)
>
> How do I test if the condition returned was true or false?
>
I''m not entirely sure what you''re asking. Are you just looking
for

if Mapper.exists?(product.id)
  ...
else
  ...
end

Fred
> Thanks in advance.
>
> Paul Thompson
>
> --
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit this group
athttp://groups.google.com/group/rubyonrails-talk?hl=en.
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On 18 May 2010 07:41, Paul Jonathan Thompson
<rails001-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Mapper.exists?(product.id)
>
> How do I test if the condition returned was true or false?
Most simply, you would use "if"... either by wrapping a conditional
block around code to run if the condition is met, or with a "guard"
clause. If the condition evaluates as true, then the code inside the
block (or being guarded) with run :

  if Mapper.exists?(product.id)
    @mapper = Mapper.find(product.id)
  end

  or
    @mapper = Mapper.find(product.id) if Mapper.exists?(product.id)

But there''s plenty of other ways of logically checking conditions:
  "unless" is equivalent to "if !"
  Ternary operators are useful
  "case" statements have their place.
  "||=" is a lovely little Ruby idiom for checking for nil values.

If you Google for "ruby conditional logic" you''ll find lots
of
beginners guides covering this material.

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

Thanks for all the replies. It then works just as I had thought but
I''m not getting the results that I expect so I need to look a bit
further. But I now know that I am using the method correctly. Thanks
once again,

On 18 May 2010 19:33, Michael Pavling
<pavling-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On 18 May 2010 07:41, Paul Jonathan Thompson
<rails001-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> Mapper.exists?(product.id)
>>
>> How do I test if the condition returned was true or false?
>
> Most simply, you would use "if"... either by wrapping a
conditional
> block around code to run if the condition is met, or with a
"guard"
> clause. If the condition evaluates as true, then the code inside the
> block (or being guarded) with run :
>
>  if Mapper.exists?(product.id)
>    @mapper = Mapper.find(product.id)
>  end
>
>  or
>    @mapper = Mapper.find(product.id) if Mapper.exists?(product.id)
>
> But there''s plenty of other ways of logically checking conditions:
>  "unless" is equivalent to "if !"
>  Ternary operators are useful
>  "case" statements have their place.
>  "||=" is a lovely little Ruby idiom for checking for nil values.
>
> If you Google for "ruby conditional logic" you''ll find
lots of
> beginners guides covering this material.
>
> --
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On 18 May 2010 08:42, Paul Jonathan Thompson
<rails001-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Thanks for all the replies. It then works just as I had thought but
> I''m not getting the results that I expect so I need to look a bit
> further. But I now know that I am using the method correctly. Thanks
> once again,
If you post the problem you''re having, rather than asking for a
qualification on one of the solutions you thought it might be, then
you might benefit from a few more eyes on it.

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.