CODEWITHSUNDEEP
ruby-on-railscarrierwave
dan
dan

Reputation: 1080

Carrierwave - undefined method `exists?' for nil:NilClass

What's the best way to check whether the user selected a file for upload in the controller? At the moment I have - 

def create
 if @object.foo.file.exists?
   do something to object
 end

 if @object.save etc.

But this returns 'undefined method `exists?' for nil:NilClass'

In the console, 'exists?' works where it returns true, but throws the error when it should return false. I've tried 'object.save' before querying 'exists?' but it doesn't fix it.

Upvotes: 1

Views: 1463

Answers (1)

Gilles
Gilles

Reputation: 167

From the rail guides:

The object in the params hash is an instance of a subclass of IO. Depending on the size of the uploaded file it may in fact be a StringIO or an instance of File backed by a temporary file. In both cases the object will have an original_filename attribute containing the name the file had on the user's computer and a content_type attribute containing the MIME type of the uploaded file.

If the user has not selected a file the corresponding parameter will be an empty string.

So you could start by checking if your param is an empty string.

Hope this helps.

Upvotes: 1

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