Rails TypeError (can’t dump File)

For a while, I kept getting exceptions from my app in the form of "TypeError (can't dump File):". I finally found out that this was caused when I was using active_record_store with something like file_column, attachment_fu, or paperclip. Basically whenever you’re storing a file in session, that was too large for the session, you would experience this issue. Here is how to get around it: Say you have a model like so (This is using file_column):

class Model < ActiveRecord::Base
  file_column :filename

Then in your controller you would want to add a line before you redirect off to clear that session:

class Controller < ApplicationController
  def create
    @model = Model.find(params[:model])
    params[:model][:filename] = nil rescue nil # Reset value here
    redirect_to models_path(@model)

As you can see, I am resetting the filename value on the model. Now it shouldn’t complain that it can’t dump the file. Happy RAILSING!