Rails - How can I check if a variable exists and also if it has a certain value in one statement

Question

Currently if it doesn't exists I get a the undefined local variable or method error.

How can I check the value of the variable and also account for it not existing at all.

I thought && was the deal but:

if defined? aaa && aaa == '123' then puts aaa end

NameError: undefined local variable or method `aaa' for main:Object

probablykabari · Accepted Answer · 2012-08-23 19:26:59Z

8

In this case, you need the parenthetical like defined?(aaa) otherwise it is evaluating the entire expression aaa && aaa == '123' as if it were defined?(aaa && aaa == '123'). So your code is really doing this:

if defined?(aaa && aaa == '123') # returns "expression" string, and thus true
  puts aaa # the error comes from this part, since aaa is not defined.
end

edited Aug 23, 2012 at 19:26

answered Aug 23, 2012 at 19:20

probablykabari

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