Question: I'm facing the problem when i am creating database in SQL server management studio 2008. it is showing error that xpstar90.dll DLL find could not load (response 126).

Answer: 
The error `undefined local variable or method 'params'` clearly indicates that `params` are not available in your model.

Also, it's not a good idea to use params in your models. See this question [Rails How to pass params from controller to after\_save inside model](https://stackoverflow.com/questions/4725185/rails-how-to-pass-params-from-controller-to-after-save-inside-model).

Further, even if you got `params` in your model, `params[:wallet]` will not be available because that wasn't submitted from the web form.

```
# No 'wallet' key here.
Parameters: {"utf8"=>"✓", "authenticity_token"=>"7rgoJQwWFFbo4Wv6gHF2AzwQpCQwB+Pp/kaNRw/YW/k=", "user"=>{"email"=>"rmagnum2002@gmail.com", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "commit"=>"Sign Up"}

```

**UPDATE**

Creating wallet without `params`

```
  has_one :wallet, :dependent => :destroy

  after_create do |user|
    user.create_wallet
  end

```
Undefined local variable or method `params' for your user model