How to add a custom file upload validation model with rails?

Question

I want to do a file upload feature with Rails4.

Now I don't use database so I can't use the rails' validation to check if user selected a file on the browser.

But I want to do as this, a self created model:

# app/models/my_feature.rb
class MyFeature
  include ActiveModel::Model
  attr_accessor :my_file
  # How to do next?
end

I don't know how to write validation code in the model. I have tried:

validates :my_file, presence: true

But not worked. Is it also need to check validation in the controller?

The code you have posted looks appropriate. Can you elaborate on how it doesn't work and post your controller code? Calling `valid?` on an instance of `MyFeature` (without a `my_file` attribute) should return `false` and have and have a presence error in `errors[:my_file]`. — ihaztehcodez, Jul 15 '15 at 11:24

score 1 · Accepted Answer · edited May 23 '17 at 12:22

1

Though it is not the best idea but you can try some thing like a custom validation.

class MyFeature
  include ActiveModel::Model
  attr_accessor :my_file
  validate :image_validation, :if => "my_file?"  
  def image_validation
    errors[:my_file] << "size can not be zero" if my_file.size > 0
  end
end

Please check the link similar to this question.

edited May 23 '17 at 12:22

Community

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1

answered Jul 15 '15 at 12:03

Sabyasachi Ghosh

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Thank you. I have tried this in my controller: `MyFeature.new(my_file: params[:my_file]).valid?`, but it said: `undefined method `size' for nil:NilClass`. If user didn't choose a file from view, that param will be nil – s-cho-m Jul 16 '15 at 02:50
Valid will not work if params[:my_file] is blank or nil. Please try params[:my_file].blank? .so if params[:my_file] is nil then it will return true as the size. – Sabyasachi Ghosh Jul 16 '15 at 06:59

How to add a custom file upload validation model with rails?

1 Answers1