Post and Location Association with ancestry gem - ruby-on-rails

Question

My Rails application have two model. Location and Post, Location have many post.I am Using
ancestry gem.
class Post < ActiveRecord::Base
belongs_to :location, :counter_cache => true
end
class Location < ActiveRecord::Base
include Tree
has_ancestry :cache_depth => true
has_many :posts
end
My Post Controller
class PostsController < ApplicationController
before_action :set_post, only: [:show, :edit, :update, :destroy]
def index
#posts = Post.all
end
def show
end
def new
#post = Post.new
end
def edit
end
def create
#post = Post.new(post_params)
respond_to do |format|
if #post.save
format.html { redirect_to #post, notice: 'Post was successfully created.' }
format.json { render action: 'show', status: :created, location: #post }
else
format.html { render action: 'new' }
format.json { render json: #post.errors, status: :unprocessable_entity }
end
end
end
def update
respond_to do |format|
if #post.update(post_params)
format.html { redirect_to #post, notice: 'Post was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #post.errors, status: :unprocessable_entity }
end
end
end
def destroy
#post.destroy
respond_to do |format|
format.html { redirect_to posts_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_post
#post = Post.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def post_params
params.require(:post).permit(:name)
end
end
If i am create new Post with which Location belongs in _form.html.erb
<%= form_for(#post) do |f| %>
<% if #post.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#post.errors.count, "error") %> prohibited this post from being saved: </h2>
<ul>
<% #post.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :name %><br />
<%= f.text_field :name %>
</div>
<%= select :location_id, Location.all.at_depth(4) { |l| [ l.name, l.id ] } %>
<div class="actions">
<%= f.submit %>
</div>
Browser show error message which is display bellow
ArgumentError in Posts#new

Answer 1

Not sure if this fixes your error, but:
To make the dropdown working, change the select line to:
<%= f.select :location_id, Location.all.at_depth(4) { |l| [ l.name, l.id ] } %>
This is because you want the formbuilder f to handle the creation of the form element.
You also have to whitelist the :location_id parameter in the controller:
def post_params
params.require(:post).permit(:name, :location_id)
end