CODEWITHSUNDEEP
rubyvalidationexception
anquegi
anquegi

Reputation: 11522

How to raise multiple exceptions in ruby

In ruby you can resque, multiple excetions like this:

begin
   ...
rescue Exception1, Exception2
  ...
rescue Exception1
  ...
rescue Exception2
  ...
end

But I do not know how to raise multiple exceptions:

1] pry(main)> ? raise

From: eval.c (C Method):
Owner: Kernel
Visibility: private
Signature: raise(*arg1)
Number of lines: 13

With no arguments, raises the exception in $! or raises
a RuntimeError if $! is nil.
With a single String argument, raises a
RuntimeError with the string as a message. Otherwise,
the first parameter should be the name of an Exception
class (or an object that returns an Exception object when sent
an exception message). The optional second parameter sets the
message associated with the exception, and the third parameter is an
array of callback information. Exceptions are caught by the
rescue clause of begin...end blocks.

   raise "Failed to create socket"
   raise ArgumentError, "No parameters", caller

Or I cannot figure this in the raise doc

The purpouse of this is that I have an API call, this call tries to create an object in the API. Then the APi could return all the problems in the object, from Activerecord Validators, So I can get thinks like that such as:

422 "The Item is not even","The Item needs too be bigger than 100" 422 "The Item is not even" 200 OK "Item created" 500 "I'm a tee pot

The idea is to capture this and raise exceptions like this

Begin
API CALL
rescue ItemnotEven,ItemnotBigger
do something 
retry if 
rescue ItemnotEven
retry if
rescue Connection error
Log cannot connect
end

Upvotes: 2

Views: 4089

Answers (3)

ndnenkov
ndnenkov

Reputation: 36101

Exceptions shouldn't be used for validations. Basically you shouldn't traverse the stack for validations in general.

What you fundamentally are doing is:

X is top level and can handle everything. X calls Y. Y calls Z. Z performs validations and does something after that, raising an exception if validation failed.

What you should be doing is:

X calls Y. Y calls V and X. V performs validations and returns result based on if the thing was valid. Y doesn't get to call X if V said the thing was invalid. Y propagates the invalidness or the successful result to X. X does what it would have done with if/else on the validity, rather than rescue.

But lets say you really want to do it. You should use throw/catch instead:

def validate_date(date)
  errors = []

  errors << 'Improper format' unless date.match?(/^\d{2}-\d{2}-\d{4}$/)
  errors << 'Invalid day' unless date.match?(/^[0-3]\d/)
  errors << 'Invalid month' unless date.match?(/-[12]\d-/)
  errors << 'Invalid year' unless date.match?(/[12][90]\d{2}$/)

  throw(:validation, errors) unless errors.empty?
end

def invoke_validation_and_do_stuff(date)
  validate_date(date)
  puts "I won't be called unless validation is successful for #{date}"
end

def meaningless_nesting(date)
  invoke_validation_and_do_stuff(date)
end

def more_meaningless_nesting(date)
  meaningless_nesting(date)
end

def top_level(date)
  validation_errors = catch(:validation) do
    more_meaningless_nesting(date)
    nil
  end

  if validation_errors
    puts validation_errors
  else
    puts 'Execution successful without errors'
  end
end


top_level '20-10-2012'
  # I won't be called unless validation is successful for 20-10-2012
  # Execution successful without errors

top_level '55-50-2012'
  # Invalid day
  # Invalid month

Upvotes: 5

ForeverZer0
ForeverZer0

Reputation: 2496

No such concept exists, in any language that I am aware of. You can raise a single exception consecutively, but not raising multiple exceptions at one time, and even if working on multiple threads to raise "simultaneously", it is still a single exception being raised on different control flows.

When an exception is raised, control flow goes to that exception. You have two options: do something about it, or crash. There is no third option, and no separate control flow popped up and is continuing on until this exception is dealt with accordingly.

If you want to see multiple failures as you stated in a comment, then you will still be doing it one at a time, as is how they would be raised. Exception gets raised, you inspect, log, do whatever, suppress it, and see the next if one gets raised for something else.

If you are asking how multiple unhandled exceptions can be raised, then it really doesn't make sense. It is akin to asking how to be in two places at once.

Upvotes: 1

Subash
Subash

Reputation: 3168

I don't think you can raise multiple exceptions, it'll raise the first exception it finds and will be caught by the innermost rescue statement if multiple exist or depends on the type of exception you raise and type of rescue

Upvotes: 1

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