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

Rails
1

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

2

On May 18, 7:41 am, Paul Jonathan T. [email protected] 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

3

On 18 May 2010 07:41, Paul Jonathan T. [email protected] 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.

4

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,

5

On 18 May 2010 08:42, Paul Jonathan T. [email protected] 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.