rails 4 Unpermitted parameters: post_detail

rails 4 Unpermitted parameters: post_detail

I am getting following error in console
Unpermitted parameters: post_detail
Unpermitted parameters: post_detail
My post model has
has_many :post_details
accepts_nested_attributes_for :post_details
and my post_detial model has
belongs_to :post
has_attached_file :upload
post.rb and post_detail.rb is my model files posts_controller is
controller Here is my form
Here is my posts_controller.rb
def create
@post = Post.new(post_params)
@post.build.post_detail
end
private
def post_params
params.require(:post).permit(:title,:post_details =>
[:upload_file_name,:upload_file_size,:upload_file_content])
end