Mysterious associations

I have a issue with simple associations which I cannot explain. I have
created a simple model Post with two attributes 'name' and 'date'. I
use the following migration:

class CreatePosts < ActiveRecord::Migration
  def self.up
    create_table :posts do |t|
      t.column :name, :string
      t.column :date, :datetime
    end
  end

  def self.down
    drop_table :posts
  end
end

In the console I create a new Post:

p = Post.new

=> #<Post:0xb79aa788 @new_record=true, @attributes={"name"=>nil,
"date"=>nil}>

Then I assign the value "5" to both name and date:

p.name = "5"

=> "5"

p.date = "5"

=> "5"

And check the assignments:

p

=> #<Post:0xb79aa788 @new_record=true, @attributes={"name"=>"5",
"date"=>"5"}>

p.name

=> "5"

p.date

=> nil

Why does the object p have the attributes both set to "5" but when I
use the association it turns up with nil for the associated date.

Can anybody explain this?

Thanks,
René

I know the string "5" is not a valid datetime. My question is why the
string shows up in the inspection of the object:

p

=> #<Post:0xb79aa788 @new_record=true, @attributes={"name"=>"5",
"date"=>"5"}>

but is not accessible:

p.date

=> nil

p.send(:date)

=> nil

p.attributes

=> {"name"=>"5", "date"=>nil}

Cheers,
René

Hi,