Can't Dup Nilclass on Association Methods

Can't dup NilClass on association methods

Got it.

From here,

Some of the classes inherited or
included in your engine controllers
may fail to get unloaded and cause
trouble after the first request to
your system.

For me, it was because I had a file in the lib that was monkey patching User model and the
User model class in this file was not getting cached I suppose.

Calling unloadable in that class in the lib folder did the trick. So my lib file looks like this

class User < ActiveRecord::Base
  unloadable
  # stuff...
end

Thanks anyways.

can't dup NilClass - Error

Why are you marking the Child as unloadable? Is there a good reason for this? if not, I'd remove.

Rails API says "Unloadable constants are removed each time dependencies are cleared."

Does the error happen when you change it to:

class Child < Parent
  has_many :parents, :foreign_key => "child"
end

And, I may be overstepping, but this seems more standard:

class Child
  belongs_to :parent
end

class Parent
  has_many :children, :dependent=>:destroy
end

Active record destroy give me Can't dup NilClass

Is it possibly somehow confusing your Node class with this one?
http://apidock.com/ruby/REXML/Node

can't dup NilClass when using Sanitize gem

This will happen if you pass nil into clean() instead of a string. Make sure your string variable is really a string.

Rails can't dup NilClass error on params

My mistake. I apologize profusely for this, but I was using paginate inappropriately. I wish I could delete this question, but there doesn't seem to be a way. The proper way to use it is:

paginate(:page => params[:page]

I guess that's what happens when you've been staring at code for too long :)

Maybe it will help others deal with Paginate. I really like it, but the errors could really be a little more descriptive.

For example, I will always get an unknown method error unless I do this:

<%= will_paginate @artists if @artists.respond_to? :total_pages %>

undefined method `username' for nil:NilClass when adding has_many through association

This is your problem in the User model...

has_many :goals, dependent: :destroy
has_many :participations, dependent: :destroy
has_many :goals, through: :participations, source: :goal

You've defined has_many :goals twoice, so the line

@goal = current_user.goals.build(goal_params)

Doesn't build the @goal object correctly.

Try this instead...

has_many :goals, dependent: :destroy
has_many :participations, dependent: :destroy
has_many :participants_goals, through: :participations, class_name: 'Goal'

How to add a has_many association on all models

Thanks to Rich Kilmer (of InfoEther), we found the elegant (and slightly opaque) way of fixing this:

# config/initializers/has_many_notes.rb
module ActiveRecord
  class Base
    def self.inherited(klass)
      super
      klass.send :has_many, :notes, :as => :notable
      klass.send :accepts_nested_attributes_for, :notes
    end
  end
end

Now no inheritance changes, and it's very DRY

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