Newbie stumped by "NameError in "

Rails
1

Help. I cannot find any help by searching…

I’m slowly creating an application using tutorial examples, etc, but I
think I’m missing something real basic:

Here’s the error message:
NameError in Mindreadr#display_images_from_mindreadr
undefined local variable or method `mindreadr_open_socket’ for
#<#Class:0x37c3b08:0x37c3a30>

Here are what I think are the key files:

display_images_from_mindreadr.rhtml (The “<%=” is the source of the
error)

I need to Open a Socket to MindReadr
<%= mindreadr_open_socket %>
Then Request some images
Then display the images
(without the <%= line, I get the other lines as text as I expected)

mindreadr_open_socket (I don’t think this is the problem…never gets
here…if you can see a problem with this code, let me know!)

require “socket”
STDOUT.flush
s = TCPSocket.open(“192.168.107.10”, 9000)
result = “MindReadr Request called”

mindreadr_controller.rb (mindreader_open_socket is defined here)
class MindreadrController < ApplicationController
def index
end

def display_images_from_mindreadr
    #  Basic action which calls _open_socket, _request, and _read
    render(:layout => false)
end

def mindreadr_open_socket
    #  Connect to MindReader server/port
    render(:layout => false)
end

def mindreadr_request
    #  Ask MindReadr for some images
    render(:layout => false)
end

def mindreadr_read
    #  Read output from MindReadr
    render(:layout => false)
end

def ajax_example
    render(:layout => false)
end

index.rhtml (partial- this all works fine until I hit the action button)

        <div id="mindreadrread_results">The images should go here

after clicking “click here”
<%= link_to_remote(“Click here for images for images to appear
above”,
:update => ‘mindreadrread_results’,
:url => { :action =>
:display_images_from_mindreadr }) %>

Something tells me I haven’t declared something in the right place.
Suggestions for debugging?

Thanks,
Dave

2

Your error is saying that the variable (mindreadr_open_socket) you’re
using
is not set so when you try to display it it says that there is a
“undefiined
local variable or method”

You should also use: @mindreadr_open_socket

I’m not sure if this is convention or necessary but I’d do it :slight_smile:

As a quick test just add:
@mindreadr_open_socket = ‘hello world’

as the first line in your “def display_images_from_mindreadr” method.

Don’t forget to update your code to:

<%= @mindreadr_open_socket %> in the rhtml

  • Byron
3

David T-L wrote:

display_images_from_mindreadr.rhtml (The “<%=” is the source of the
error)

I need to Open a Socket to MindReadr
<%= mindreadr_open_socket %>
Then Request some images
Then display the images
(without the <%= line, I get the other lines as text as I expected)

Are you trying to call the controller.mindreadr_open_socket method from
the view ? I don’t think that will work. I think, however, if you
move that method to the helper, it can be called from the view.

Also, unless the method returns a string that you want displayed, you
need to use <% %> rather than <%= %>

It may be you want something more like something more like:

— in the helper —

def mindreadr_open_socket
socket = create__and_open_the_socket_somehow
end

—in the view—

<% socketthing = mindreadr_open_socket %>

…blah blah…
<% for blah %>
<%= socketthing.get_data %>
<% end %>

<% sockething.close %>

4

Alan,

I think you are exactly right. I still don’t understand all of the
scafolding interconnectedness. Thanks for giving me such a complete
answer. I need to study it and give it a try.

Thanks for taking the time to “solve” my real problem.
Dave

Alan F. wrote:

David T-L wrote:

display_images_from_mindreadr.rhtml (The “<%=” is the source of the
error)

I need to Open a Socket to MindReadr
<%= mindreadr_open_socket %>
Then Request some images
Then display the images
(without the <%= line, I get the other lines as text as I expected)

Are you trying to call the controller.mindreadr_open_socket method from
the view ? I don’t think that will work. I think, however, if you
move that method to the helper, it can be called from the view.

Also, unless the method returns a string that you want displayed, you
need to use <% %> rather than <%= %>

It may be you want something more like something more like:

— in the helper —

def mindreadr_open_socket
socket = create__and_open_the_socket_somehow
end

—in the view—

<% socketthing = mindreadr_open_socket %>

…blah blah…
<% for blah %>
<%= socketthing.get_data %>
<% end %>

<% sockething.close %>

5

Byron,

Thank you. That made the error message go away. I see I have to
initialize the variable. However, I really thought I was constructing
an action. So I think I have a deeper problem.

Dave

Byron S. wrote:

Your error is saying that the variable (mindreadr_open_socket) you’re
using
is not set so when you try to display it it says that there is a
“undefiined
local variable or method”

You should also use: @mindreadr_open_socket

I’m not sure if this is convention or necessary but I’d do it :slight_smile:

As a quick test just add:
@mindreadr_open_socket = ‘hello world’

as the first line in your “def display_images_from_mindreadr” method.

Don’t forget to update your code to:

<%= @mindreadr_open_socket %> in the rhtml

  • Byron