Sinatra: NameError at '/route', undefined local variable or method - ruby

Question

I'm trying to build an admin backend for a cms website.
this is the structure of my application
├── app.rb
├── Gemfile
├── models
│   └── models.rb
├── routes
│   └── routes.rb
└── views
├── categories.erb
├── # ... other view files
app.rb
require 'sinatra'
require 'data_mapper'
require 'dm-core'
require 'dm-migrations'
require 'digest'
enable :sessions
DataMapper.setup(:default, 'mysql://username:password#localhost/database')
require './models/models.rb'
require './routes/routes.rb'
DataMapper.finalize
models.rb
class Category
include DataMapper::Resource
property :id, Serial
property :name, String
has n, :posts
end
# other model definitons
I've defined a categories route inside my routes.rb
...
get '/categories' do
#categories = Category.all
erb :categories
end
...
Contents of view (categories.erb) file.
#table headers
<tbody>
<% #categories.each do |c| %>
<tr>
<td>
<%= c.id %>
</td>
<td>
<%= c.name %>
</td>
<td>
<%= с.posts.count %>
</td>
<td>
<%= c.posts(:order => [:updated_at.desc]).first.updated_at.strftime("%d/%m/%Y") %>
</td>
</tr>
<% end %>
</tbody>
When I browse to /categories route, server spits this error
NameError at /categories
undefined local variable or method `с' for #<Sinatra::Application:0x0000000284bc08>
I have not faced such problem before. And really don't know what is going on.
The problem probably is not with application structure (the require sequences inside app.rb) because, before get '/categories' I've defined a post '/login' route which checks user inputs against database records. And it works as I want.
post '/login' do
email = params[:email]
pwd = params[:password]
user = Author.first(:email=>email)
if user.nil?
redirect to ('/register')
elsif !user.nil?
if Digest::MD5.hexdigest(pwd) == user.password
... #and so on
UPDATE
I'm listing other table/models with same methods, and all of them works as i expected, but categories.
other routes
get '/articles' do
#articles = Post.all(:is_blog_post => false)
erb :site_articles
end
##blog articles
get '/blogposts' do
#barticles = Post.all(:is_blog_post => true)
erb :blog_articles
end
#users
get '/admin_users' do
#admins = Author.all(:is_admin=>true)
erb :admin_users
end
#bloggers
get '/bloggers' do
#bloggers = Author.all(:is_admin=>false)
erb :blog_users
end
and corresponding view files
site articles
<tbody>
<% #articles.each do |art| %>
<tr>
<td>
<%= art.title %>
</td>
<td>
<%= art.author.full_name %>
</td>
<td>
<%= art.category.name %>
</td>
<td>
<%= art.updated_at.strftime("%d/%m/%Y %H:%M") %>
</td>
<td>
<%= art.featured? ? "Yes" : "No" %>
</td>
</tr>
<% end %>
</tbody>
blog articles
<tbody>
<% #barticles.each do |art| %>
<tr>
<td>
<%= art.title %>
</td>
<td>
<%= art.author.full_name %>
</td>
<td>
<%= art.category.name %>
</td>
<td>
<%= art.updated_at.strftime("%d/%m/%Y %H:%M") %>
</td>
<td>
<%= art.featured? ? "Yes" : "No" %>
</td>
</tr>
<% end %>
</tbody>
admins
<tbody>
<% #admins.each do |admin| %>
<tr>
<td>
<%= admin.full_name %>
</td>
<td>
<%= admin.email %>
</td>
<td>
<%= !admin.twitter.nil? ? admin.twitter : "N/A" %>
</td>
<td>
<%= !admin.facebook.nil? ? admin.facebook : "N/A" %>
</td>
<td>
<%= !admin.phone.nil? ? admin.phone : "N/A" %>
</td>
<td>
<%= admin.posts.count %>
</td>
</tr>
<% end %>
</tbody>
bloggers
<tbody>
<% #bloggers.each do |blogger| %>
<tr>
<td>
<%= blogger.full_name %>
</td>
<td>
<%= blogger.email %>
</td>
<td>
<%= !blogger.twitter.nil? ? blogger.twitter : "N/A" %>
</td>
<td>
<%= !blogger.facebook.nil? ? blogger.facebook : "N/A" %>
</td>
<td>
<%= !blogger.phone.nil? ? blogger.phone : "N/A" %>
</td>
<td>
<%= blogger.posts.count %>
</td>
</tr>
<% end %>
</tbody>

Answer 1

You’ve somehow got an odd character in your source. That’s not a “normal” latin c in the line <%= с.posts.count %>, it’s U+0441, CYRILLIC SMALL LETTER ES. It just looks like a latin c.
To fix it just delete the character and re-write it with a normal c.