Custom validation for file size in rails before being uploaded

Question

in my form i have

<%= label_tag("file", "Attachment:") %><%= file_field_tag "uploadfile" %>

In my model i would like to write this

validate :validates_uploadfile

def validates_uploadfile(file)
    max_size = 2048
    errors.add(:uploadfile, "File size exceeds limitation") if file.size > max_size
end

In my controller can i call something like this

validates_upload_file(params[:uploadfile])

Is there a way to validate a file upload before being uploaded(not by using javascript or by looking at the file extension)
Thanks for the help

UPD

validate :uploadfile_validation, :if => "uploadfile?"

def uploadfile_validation
    errors[:uploadfile] << "should be less than 1MB" if uploadfile.size > 1.megabytes
end

Solution 1

Here's my code for size validations (I use CarrierWave for uploads).

  validate :picture_size_validation, :if => "picture?"  

  def picture_size_validation
    errors[:picture] << "should be less than 1MB" if picture.size > 1.megabytes
  end

Cheers.

Solution 2

You can use:

validates_size_of :picture, maximum: 1.megabytes, message: "should be less than 1MB"

Solution 3

If I am not mistaken, then all those methods above check the file size once its been uploaded ( and maybe even processed ) but what happens if I choose a 1GB file in file input field for pictures considering that javascript validation is absent or javascript is just disabled? It probablt gets uploaded, taking a lot of time just to tell ya that its too big, that just aint right. I am a newbie so I might be wrong about something ...

Comments

[Hishalv]

hi, i have edited my code above, however i get an error undefined local variable or method `uploadfile', any thoughts. iam not using carrierwave or paperclip, i am uploading directly to s3.

[Lucas]

Try something like "!uploadfile.blank?" instead of "uploadfile?" - I think picture? is a method defined by CarrierWave

[Hishalv]

thanks for the help, i finally installed carrierwave, as things were not working out, after some time i got the above code snippet to work, thanks again.

[toy]

Does this size of the file get checked before or after the file is uploaded?

[Lucas]

Before uploading. I just checked right now because I had a doubt but it works fine.

[Anwar]

This works, but not before upload. File will be uploaded into the cache

[Rustam A. Gasanov]

yep, client_max_body_size 5M

[MCB]

@RustamA.Gasanov So, just to make sure. If I write absolutely no code any files larger than 5 MB wont upload?

[Rustam A. Gasanov]

@MCB correct, check this link nginx.org/en/docs/http/…

[Filipe Gorges Reuwsaat]

I'd stay away from adding validation within a web server configuration file

[Andrey]

Rails 5: ..., if: -> { picture }