I have a system where uploads are stored in a database with a filename
based on the MD5 hash of the file contents. Following the logic of this,
I assigned upload_file_name to be a unique index in my migration.
What I want to do is, whenever a user tries to upload a file whose md5
hash already exists in the database, just redirect to that other record
rather than making a copy (which actually just throw an error because
upload_file_name is a unique index)
So I put in my model:
self = other_upload if other_upload =
Upload.find_by_upload_file_name(self[:upload_file_name])
which ActiveRecord doesn’t let me do saying “Can’t change the value of
self”
self = other_upload if other_upload =
Upload.find_by_upload_file_name(self[:upload_file_name])
which ActiveRecord doesn’t let me do saying “Can’t change the value of
self”
That is not an ActiveRecord issue it is a basic Ruby issue. Once you
are inside an instance method I do not think there is any way of
suddenly deciding you want to be in the method of a different object.
You could put something like the above code in a method of the model
that, rather than setting self, returns either itself or the
alternative, then call that method from the controller.
I guess I just have to do it in the controller – I just wish there was
some way I could put it into the model that way I never have to worry
about it in
my “skinny controller”.
I know I have to do it in the controller is just wish there was some way
I could put it into the model that way I never have to worry about it in
my “skinny controller”.
find_or_initialize_by_?
Although, if you’re doing some fudging with MD5 hashes, you may not be
able to use the dynamic methods…
upload.rb
def self.find_or_initialize_by_params(params)
upload = Upload.new(params)
return Upload.find_by_upload_file_name(upload.upload_file_name) ||
upload
end