undefined method `posts_path' for #<#<Class:0x007fe3547d97d8>:0x007fe3546d58f0> - ruby-on-rails

Question

I'm new to rails and I'm getting this error:
undefined method `posts_path' for #<#<Class:0x007fe3547d97d8>:0x007fe3546d58f0>
I've posted my files below, please keep in mind I'm new to rails so simple explanations would be really appreciated!
Route.rb:
Rails.application.routes.draw do
get '/post' => 'post#index'
get '/post/new' => 'post#new'
post 'post' => 'post#create'
end
post_controller.rb:
class PostController < ApplicationController
def index
#post = Post.all
end
def new
#post = Post.new
end
def create
#post = Post.new(post_params)
if #post.save
redirect_to '/post'
else
render 'new'
end
end
private
def post_params
params.require(:post).permit(:content).permit(:title)
end
end
new.html.erb:
<%= form_for(#post) do |f| %>
<div class="field">
<%= f.label :post %><br>
<%= f.text_area :title %>
<%= f.text_area :content %>
</div>
<div class="actions">
<%= f.submit "Create" %>
</div>
<% end %>

Answer 1

I'm guessing form_for(#post) expects there to be a method called posts_path and one doesn't exist because it hasn't been defined in your routes file. Try replacing:
Rails.application.routes.draw do
get '/post' => 'post#index'
get '/post/new' => 'post#new'
post 'post' => 'post#create'
end
with
Rails.application.routes.draw do
resources :posts, only: [:new, :create, :index]
end
Edit: more info:
Read the full page on form helpers at http://guides.rubyonrails.org/form_helpers.html, and inparticular, read the section on "2.2 Binding a Form to an Object" and the part that says:
When dealing with RESTful resources, calls to form_for can get
significantly easier if you rely on record identification. In short,
you can just pass the model instance and have Rails figure out model
name and the rest:
## Creating a new article
# long-style:
form_for(#article, url: articles_path)
# same thing, short-style (record identification gets used):
form_for(#article)
## Editing an existing article
# long-style:
form_for(#article, url: article_path(#article), html: {method: "patch"})
# short-style:
form_for(#article)
Notice how the short-style form_for invocation is conveniently the
same, regardless of the record being new or existing. Record
identification is smart enough to figure out if the record is new by
asking record.new_record?. It also selects the correct path to submit
to and the name based on the class of the object.
So, knowingly or not, when you say form_for(#post), you're asking rails to guess the route that your form should be submitted to, based on the name of your #post variable. The routes that you had defined didn't match what rails expected them to be.
For more on routing in rails read the entire page at http://guides.rubyonrails.org/routing.html, and inparticular pay attention to the section "2 Resource Routing: the Rails Default". Your form_for(#post) will assume that you're using "resource routing", which is what I switched to.
As for why your getting a new error? There's somewhere else in your app where you were expecting to use your previous custom defined routes, and now you're using rails "resource routes" so your path names will be different. No route matches [GET] "/post/new" because now the route instead matches No route matches [GET] "/posts/new" (note the plural posts).

Answer 2

Here the form is try to find a route to a post_method through a path "posts_path"
So you need to define in your routes.rb file.
Rails.application.routes.draw do
get '/post' => 'post#index'
get '/post/new' => 'post#new'
post '/posts' => 'post#create'
end

Answer 3

The problem arises from the views. Rails cannot recognize the path that will run when the form is submitted.
You can manually change your form_for tag to point to the appropriate url.
<%= form_for #post, :url => "enter_your_path_here" do |f| %>
This solved my similar problem

Answer 4

you need to rename the post controller and the corresponding files to plural. that's posts not post. and then the route too needs to be resources :posts.
don't forget to change the class name of your post controller to be plural.