How can i use Rails' update_attributes with a file upload?

My update method of a Product controller is defined as follows:

def update
  @product = Product.find(params[:id])

  if params[:product][:image_path]
    # Check if this product already has an image
    File.delete(@product.full_image_path) if File.exist?(@product.full_image_path)
    # Upload the new image
    uploaded_img = params[:product][:image]
    @product.image_path = Time.now.to_i.to_s + File.extname(uploaded_img.original_filename)
    File.open(@product.ful开发者_JAVA技巧l_image_path, 'w') do |file|
      file.write(uploaded_img.read)
    end
  end

  @product.name = params[:product][:name]
  @product.description = params[:product][:description]

  respond_to do |format|
    if @product.errors.count == 0
      format.html { redirect_to products_path, :notice => t(:product_updated) }
      format.xml { head :ok }
    else
      format.html { render :action => "edit" }
      format.xml { render :xml => @product.errors, :status => :unprocessable_entity }
    end
  end
end

This simply deletes the old image if already present, and uploads the new one. It also updates the Product attributes

How can I use @product.update_attributes(params[:product]) to avoid updating name and description attributes as I've done here?

If I do @product.update_attributes(params[:product]) I get an error because the params hash contains a value named "image" which is not an attribute of the object.

Thanks in advance

You could create an attribute setter for the image in the Product model called image=:

def image=(uploaded_img)
  # Check if this product already has an image
  File.delete(full_image_path) if File.exist?(full_image_path)
  # Upload the new image
  image_path = Time.now.to_i.to_s + File.extname(uploaded_img.original_filename)
  File.open(full_image_path, 'w') do |file|
    file.write(uploaded_img.read)
  end
end

After that, remove the rest of the code in the controller and use @product.update_attributes(params[:product]). I didn't tried it but I think it should work.

Do you know that you have some gems that allow to manage easily file upload like https://github.com/jnicklas/carrierwave or https://github.com/thoughtbot/paperclip

You should try to refactor your controller a bit, a controller should not be running any other tasks other than directing the traffic of your models and views. Try to move all your file operations to a separate helper.