Silly Error!

What am I missing here?

Controller
    def add_history
      @history = History.new
      Patient.find(params[:id]).history.create(params[:history])
      flash[:notice] = "Added History"
      redirect_to :action =>"show", :id => params[:id]
    end

Models
Patient
   has_one :history
History
belongs_to :patients

when I try to add a History I get

You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occured while evaluating nil.create

What am I missing here?

Controller
def add_history
@history = History.new
Patient.find(params[:id]).history.create(params[:history])
flash[:notice] = “Added History”

  redirect_to :action =>"show", :id => params[:id]
end

Models
Patient
has_one :history
History
belongs_to :patients

when I try to add a History I get

You have a nil object when you didn’t expect it!

You might have expected an instance of ActiveRecord::Base.
The error occured while evaluating nil.create

I believe your thinking that a has_one assocaition has a create method like a has_many. The has_one association works a bit different. Your patient will have a create_history method instead. You could rewrite this as

from
def add_history
@history = History.new # Does nothing You don’t re-assign it.
Patient.find(params[:id]).history.create( params[:history])

flash[:notice] = “Added History”
redirect_to :action =>“show”, :id => params[:id]
end

to

def add_history
@history = Patient.find( params[:id] ).create_history( params[:history] ) || History.new
flash[:notice] = “Added History”
redirect_to :action => “show”, :id => params[:id]
end

This will effectivley give the same functionality as you have.

You may want to add a bit of a rescue clause in the case that the Patient is not found. Or use find_by_id which doesn’t throw an Exception immediatley, but will when you call create_history on nil.

Hope that helps
Daniel

Thats perfect!

Thank you very much indeed