Rails beginner, initialize object

Question

In rails default controller the new method makes an object, and the create method is used later to save that.

I want to set a mod_user field in the DB, without it being input into the form.

Based on this link http://api.rubyonrails.org/classes/ActiveRecord/Base.html I've tried adding the following to my pages controller.

  def new
    @page = Page.new(:n_publisher_id => session[:n_publisher_id])

or

  def create
    page = Page.new(params[:page])
    page.n_publisher_id = session[:n_publisher_id]

But it is saving as NULL If I put this in the controller and model then I get nil object errors from ActiveRecord

  def new
    @page = Page.new(1)

  def initialize(n_publisher)
    @n_publisher_id = n_publisher
  end

I have attr_accessor :n_publisher_id included in my page model. This works in the console...

>> @i = Page.new
=> #<Page id: nil, fk_issue: nil, n_status_id: nil, dt_published_datetime: nil, dt_offline_date: nil, dt_created_date: nil, n_publisher_id: nil, created_at: nil, updated_at: nil, page_name: nil>
>> @i.n_publisher_id
=> nil
>> @i.n_publisher_id = 1
=> 1
>> @i.n_publisher_id
=> 1

Here is schema of the pages table

mysql> show fields from pages;
+-----------------------+--------------+------+-----+---------+----------------+
| Field                 | Type         | Null | Key | Default | Extra          |
+-----------------------+--------------+------+-----+---------+----------------+
| id                    | int(11)      | NO   | PRI | NULL    | auto_increment |
| fk_issue              | int(11)      | YES  |     | NULL    |                |
| n_status_id           | int(11)      | YES  |     | NULL    |                |
| dt_published_datetime | datetime     | YES  |     | NULL    |                |
| dt_offline_date       | datetime     | YES  |     | NULL    |                |
| dt_created_date       | date         | YES  |     | NULL    |                |
| n_publisher_id        | int(11)      | YES  |     | NULL    |                |
| created_at            | datetime     | YES  |     | NULL    |                |
| updated_at            | datetime     | YES  |     | NULL    |                |
| page_name             | varchar(255) | YES  |     | NULL    |                |
+-----------------------+--------------+------+-----+---------+----------------+
10 rows in set (0.00 sec)

Here is the model

class Page < ActiveRecord::Base
  has_many :slots, :dependent => :destroy
  accepts_nested_attributes_for :slots

  #attr_accessor :n_publisher_id
  #attr_accessible :n_publisher_id
end

Create Action

  def create
    page = Page.new(params[:page].merge({:n_publisher_id => 1}))
    #page.dt_created_date = Date.today

    page.n_publisher_id = 1

    respond_to do |format|
      if page.save
        format.html { redirect_to(page, :notice => 'Page was successfully created.') }
        format.xml  { render :xml => page, :status => :created, :location => page }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => page.errors, :status => :unprocessable_entity }
      end
    end
  end

Answer 1

Did you verify already that session[:n_publisher_id] has a value != nil?

A quick verification in your controller, try:

def create
    page = Page.new(params[:page])
    page.n_publisher_id = 3
end

If all the newly created pages have n_publisher_id == 3, then session[:n_publisher_id] == nil and must be set somewhere in your app.

Answer 2

You should never overwrite the initialize method of your ActiveRecord object. Rails is doing a bunch of stuff behind the scenes and it's known to mess things up.

Instead just append your attribute onto your initial params that you're passing in.

So, assuming :n_publisher_id is a real attribute of your AR object (column in the table), something like:

@page = Page.new(params[:page].merge({:n_publisher_id => session[:n_publisher_id]}) 

should work.

This also assumes that session[:n_publisher_id] is also not nil (otherwise, of course it will be saved as nil in the db)

Answer 3

It sounds like session[:n_publisher_id] is nil. Or you are overwriting it somewhere.

If you have the value available in the create action, merge in the params there and you don't need to bother setting it in the new action.

If you only have it available in the new action for some reason, use a hidden field

My gut tells me that you should be setting this explicitly and actually not allowing mass assignment, but I don't know your use case.

Answer 4

Remove attr_accessor :n_publisher_id from your model. It is column in db, so Rails took care for it. Maybe your attr_accessor overrides something.