Overly Complex "Create" Method

gistfile1.rb

class SessionsController < ApplicationController
  def new
  end

  def create
    @user = User.where(email: params[:session][:email].downcase).first
    if @user && @user.authenticate(params[:session][:password])
      log_in @user
      if session[:user_role] == :partner
        redirect_to partner_path @user.id
      elsif session[:user_role] == :admin
        redirect_to admin_path @user.id
      end
    else
      flash.now[:danger] = 'Invalid email/password combination'
      render 'new'
    end
  end


  def destroy
    log_out
    #redirect_to root_url
  end
end

I'm assuming that session[:user_role] is not known until after the auth step completes. (If it was known at the time the controller is called, I'd suggest having 2 separate Session#create_for_admin and Session#create_for_partner.)
One possibility otherwise is to make a helper method that, for example, encapsulates line 7-14 but instead of doing a redirect it returns either a path to redirect to, or else nil (meaning authentication failed or whatever, and you should drop to line 15). How's that?