Lynda Ruby on Rails 4必不可少的培训

Question

On chapter 14 the instructor creates an action on a controller without a corresponding view template and it works properly while I get error "missing template". Anyone else that has gotten that far to that issue your help is appreciated. (Sorry if I am missing expected items, first time posting here.)

Error: Template is missing Missing template access/attempt_login, application/attempt_login with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby]}. Searched in: * "/var/www/html/railsLdapTest/app/views" * "/usr/local/rvm/gems/ruby-2.1.8/gems/devise-4.0.0/app/views"

View that calls "attempt_login":

<% @page_title = "Admin Login" %>

<div class="login">
<%= form_tag(:action => 'attempt_login') do %>
<table>
<tr>
  <td><%= label_tag(:username) %></td>
  <td><%= text_field_tag(:username) %></td>
</tr>
<tr>
  <td><%= label_tag(:password) %></td>
  <td><%= password_field_tag(:password) %></td>
</tr>
<tr>
  <td>&nbsp;</td>
  <td><%= submit_tag("Log In") %></td>
</tr>
</table>
<% end %>
</div>

Lynda action code:

def attempt_login
  if params[:username].present? && params[:password].present?
    found_user = AdminUser.where(:username => params[:username]).first
    if found_user
      authorized_user = found_user.authenticate(params[:password])
    end
  end

  if authorized_user
    # mark user as logged in
    session[:user_id] = authorized_user.id
    session[:username] = authorized_user.username
    flash[:notice] = "You are now logged in."
    redirect_to(:action => 'index')
  else
    flash[:notice] = "Invalid username/password combination."
    redirect_to(:action => 'login')
  end
end

My code modified to connect to a database via LDAP:

def attempt_login
  if params[:username].present? && params[:password].present?
    ldap = Net::LDAP.new
    ldap.host = '172.16.15.3'
    ldap.port = 389
    ldap.auth params[:username], params[:password]

    if ldap.bind
      ldap.search(
        base: "DC=abc,DC=net",
        filter: Net::LDAP::Filter.eq( "mail", params[:username] + "@abc.net" ),
        attributes: [ 'objectGUID','cn', 'telephoneNumber' ],
        return_result:true
      ) do |entry|
        @var1 = entry.telephoneNumber
        authorized_user = entry.cn
      end

      if authorized_user
        # mark user as logged in
        session[:user_id] = authorized_user
        session[:username] = authorized_user
        flash[:notice] = "You are now logged in."
        redirect_to(:action => 'index')
      else
        flash[:notice] = "Invalid username/password combination."
        redirect_to(:action => 'login')
      end
    end
  end
end

Answer 1

You are going to get that error anytime you are creating actions in the controller without a corresponding view. The Lynda.com instructor probably fixed that issue "off-air" instead of using it as a teachable moment.

Please go ahead and create the corresponding view template and you will see what I mean.

If there is any doubt with my answer, then please review this: http://guides.rubyonrails.org/action_view_overview.html

In particular the part that says:

For each controller there is an associated directory in the app/views directory which holds the template files that make up the views associated with that controller. These files are used to display the view that results from each controller action.

For example, lets say I create a GuidesController:

class GuidesController < ApplicationController

end

I am not going to create CRUD actions in this example because this is not about data flow at all.

class GuidesController < ApplicationController
   def book
   end
end

The significance of this piece of the answer is that you have to map it to a view directly. So you go to views and create a directory called guides.

This is the second stage of the mapping and how ActionView is wired up.

GuidesController will only work with the view inside of guides, that is the path and so that is what the controller is going to be looking for.

This is standard Rails convention.

Now I would have to create a book.html.erb inside the views/guides directory because the way ActionView works is it takes the method of books and maps it to the book.html.erb file.

Inside of it you can put

<p>Hey, I am in the book view</p>

The last thing that needs to be done is give it a route. So in routes.rb:

get 'book' or better yet get 'guides/book'

Make sure you have previously done a rails db:create and rails db:migrate after creation of your app so that your database will be installed.

Now when you go to localhost:3000/guides/book it will render:

Hey, I am in the book view

So here you have our controller and it has an action name, the action name is wired up into a specific file and it has to be given the exact name. Technically, you can override these conventions, but that would mean writing more code and more code is rarely a good thing.

Also, do your homework in vetting web development courses, lots of them are really mediocre with their instruction and material covered.