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

rubyonrails-talk
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

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

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

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.