Rails paperclip not showing image - ruby-on-rails

Question

I am new to paperclip, and I wanted to see how it would work. I generated a simple model Monkey and got the following:
rails g scaffold monkey description age:datetime
rails g paperclip monkey facepic
rake db:migrate
Model
class Monkey< ActiveRecord::Base
has_attached_file :facepic, :styles => { :medium => "300x300>", :thumb => "100x100>" }
end
View new/edit
<%= form_for #monkey, :url => monkies_path, :html => { :multipart => true } do |f| %>
...
<div class="field">
<%= f.label :facepic %><br>
<%= f.file_field :facepic %>
</div>
View show
<%= image_tag #monkey.facepic.url %>
Controller
#monkey = Monkey.new(monkey_params)
I can create new monkeys, but the show view doesn't seem to find the uploaded file. I have no error messages, except a routing error to 'missing.png'. There is no trace to the uploaded image. I am using Rails 4.1.6. What am I missing here? How do I troubleshoot this thing? The gem is installed and also imagemagick is installed.
This is what the logs say:
ActionController::RoutingError (No route matches [GET] "/facepics/original/missing.png"):
...
Started GET "/monkies/new" for 127.0.0.1 at 2014-09-19 14:40:22 +0200
Processing by MonkiesController#new as HTML
Rendered monkies/_form.html.erb (4.0ms)
Rendered monkies/new.html.erb within layouts/application (5.0ms)
Completed 500 Internal Server Error in 12ms
ActionView::Template::Error (No route matches {:action=>"show", :controller=>"monkies"} missing required keys: [:id]):
There is no error message displayed however when I create a new monkey... :'(
EDIT:
The Monkey model is created, but the paperclip columns remain empty.

Answer 1

This error clearly show that your images are not getting saved because path and url not specified in your has_attached_file block. It should be like :
has_attached_file :facepic,
:path => ":rails_root/public/system/:attachment/:id/:style/:filename",
:url => "/system/:attachment/:id/:style/:filename",
:styles => { :medium => "300x300>", :thumb => "100x100>" },
:default_url => "path to default image"
here default_url show image that you want if no image uploaded. For more detail you can go here http://rdoc.info/gems/paperclip/4.2.0/Paperclip/ClassMethods%3ahas_attached_file .
And for other error you can follow this link Paperclip::Errors::MissingRequiredValidatorError with Rails 4

Answer 2

Starting with Paperclip version 4.0, all attachments are required to include a content_type validation, a file_name validation, or to explicitly state that they're not going to have either.
Paperclip raises Paperclip::Errors::MissingRequiredValidatorError error if you do not do any of this.
In your case, you can add any of the following line to your Post model, after specifying has_attached_file :image
Option 1: Validate content type
validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
-OR- another way
validates_attachment :image, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }
-OR- yet another way
is to use regex for validating content type.
Option 2: Validate filename
validates_attachment_file_name :avatar, :matches => [/png\Z/, /jpe?g\Z/, /gif\Z/]
Option 3: Do not validate
If for some crazy reason (can be valid but I cannot think of one right now), you do not wish to add any content_type validation and allow people to spoof Content-Types and receive data you weren't expecting onto your server then add the following:
do_not_validate_attachment_file_type :image
Note:
Specify the MIME types as per your requirement within content_type/ matches options above. I have just given a few image MIME types for you to start with.
Reference:
Refer to Paperclip: Security Validations, if you still need to verify. :)
For details you can go to This question

Answer 3

I am sorry to say that my problem eventually was a bunch of things:
Had to add :facepic to the strong params
Had to add validations of content type to the model
Paperclip has a dependency... the file-command, which isn't shipped on Windows.
which can be downloaded here: http://sourceforge.net/projects/gnuwin32/?source=typ_redirect
After all three, it works like a charm!
Thank you all!