Forum: Ruby on Rails Ruby on Rails new bee( Need help)

Hi Helpers,
                   I am new to Ruby in Rails and I have difficulty it
passing the instance varaibles to the view. Earlier I was reading the
values from the table directly in the view. Now I want to do that part 
in
controller
below is my code before changes

view....
<%= javascript_include_tag :defaults %>
<% form_tag( {:action => 'show'},{:method => :post}) %>
   <br><br>
   <b>Enter ComponentName
   <p>Search for a component to add or move </p>
   <% @complist = Components.find(:all, :select => 'DISTINCT
component_name') %>
<%= select_tag 
"component_name",options_for_select([""]+@complist.map{|u|
[u.component_name]}),:include_blank => true,:onchange =>
remote_function(:url => {:action => :setselectedcomp },:with =>
"'component_name='+value" ) %>
   <%= observe_field(:component_name,:controller =>
:comp_groups_controller, :url => {:action => 'select_groups'}, :update 
=>
:group_names, :with => "'component_name='+value" ) %>
<br>
 controller........

def setselectedcomp()
                $selected_comp = params["component_name"]
                puts "selected_comp: #{$selected_comp}"
                $selected_comp_id = Components.find(:all, :select =>
['component_id'], :condition => ["component_name = 
'#{$selected_comp}'"])
                puts "selectd_comp_id is #{$selected_comp_id}"
        end
def select_groups
                passing_comp = params["component_name"]
                puts "passing comp = #{passing_comp}"
                @belongstogroup = CompGroups.find(:all, :select =>
['group_name'], :conditions => ["component_name = '#{passing_comp}'"])
                belongstogroup.each do |num|
                 puts num.inspect
                end
                #return @belongstogroup
                render :partial => "select_groups"
        end
This is working perfectly fine

What I wanted to accomplish is
1. in the select_tag I have added the  "include_blank=true" to allow 
user
to add a value. it sisn't work for me. May i know what I did wrong
2. I am not getting the component_id value in the controller. Not sure 
what
I did wrong
  $selected_comp_id = Components.find(:all, :select => ['component_id'],
:condition => ["component_name = '#{$selected_comp}'"])
                puts "selectd_comp_id is #{$selected_comp_id}"

Appreciate your help on this.

Thanks
Sups

sups wrote in post #1097037:
> Hi Helpers,
>                    I am new to Ruby in Rails and I have difficulty it
> passing the instance varaibles to the view. Earlier I was reading the
> values from the table directly in the view. Now I want to do that part
> in
> controller
> below is my code before changes

Welcome to Ruby on Rails.

> view....
> <%= javascript_include_tag :defaults %>
> <% form_tag( {:action => 'show'},{:method => :post}) %>
>    <br><br>
>    <b>Enter ComponentName
>    <p>Search for a component to add or move </p>
>    <% @complist = Components.find(:all, :select => 'DISTINCT
> component_name') %>

It's a really good thing that you have come to us for advice. The above 
code completely breaks the Model View Controller (MVC) design pattern 
that Rails is built upon.

A view should NOT (dare I say NEVER) send messages directly to a model 
object. Components.find(...) is a message being sent directly to the 
model "Components" from your view.

I also noticed that you've thrown in (:select -> DISTINCT) in there. 
Unless you are doing something really odd, for a very specific caae, I'm 
betting this is unnecessary. If you need it for some reason, that reason 
is more than likely that you're doing something wrong. This is a big red 
flag to me just looking at the code you've shown here.

Move this to the controller...

def show
  @components = Components.all
end

In your view use the proper model based form helper. You can read all 
about that in the Rails Guides here...

http://guides.rubyonrails.org/form_helpers.html#bi...

In fact I would highly recommend that you stop everything now and read 
through:

http://guides.rubyonrails.org/getting_started.html

This is a really great place to start learning how to do Ruby on Rails 
the "right" way.

> <%= select_tag
> "component_name",options_for_select([""]+@complist.map{|u|
> [u.component_name]}),:include_blank => true,:onchange =>
> remote_function(:url => {:action => :setselectedcomp },:with =>
> "'component_name='+value" ) %>
>    <%= observe_field(:component_name,:controller =>
> :comp_groups_controller, :url => {:action => 'select_groups'}, :update
> =>
> :group_names, :with => "'component_name='+value" ) %>
> <br>

My recommendation here is to back off using more advanced features like 
observe_field until you actually understand the basics of Rails MVC 
design patterns. Keep the client side JavaScript stuff out of the 
picture until you understand what standard Rails views, controllers and 
models look like in a purely server side web application.

>  controller........
>
> def setselectedcomp()
>                 $selected_comp = params["component_name"]
>                 puts "selected_comp: #{$selected_comp}"
>                 $selected_comp_id = Components.find(:all, :select =>
> ['component_id'], :condition => ["component_name =
> '#{$selected_comp}'"])
>                 puts "selectd_comp_id is #{$selected_comp_id}"
>         end
> def select_groups
>                 passing_comp = params["component_name"]
>                 puts "passing comp = #{passing_comp}"
>                 @belongstogroup = CompGroups.find(:all, :select =>
> ['group_name'], :conditions => ["component_name = '#{passing_comp}'"])
>                 belongstogroup.each do |num|
>                  puts num.inspect
>                 end
>                 #return @belongstogroup
>                 render :partial => "select_groups"
>         end
> This is working perfectly fine

It might seem to be "working perfectly fine," but these methods do not 
follow standard Rails design patterns. Any experienced Rails developer 
would tell you the same thing. One day you may need to collaborate with 
other Rails developers and this would not get you off to a good start in 
that relationship.

Again the Rails Guides show a number of typical patterns. Here's one for 
listing Posts:

http://guides.rubyonrails.org/getting_started.html...

Notice the standard naming schemes used in the controller:

def index
  @posts = Post.all
  ...
  ...
end

Then notice how the view uses the data that was loaded by the controller 
from the Post model.

1. The request is directed to the controller through the routing system.
2. The controller loads the data by sending a message to the model (or 
models).
3. The controller renders the view, providing the loaded data through 
some Rails black magic (i.e. it makes the @posts instance variable 
available to the view).
4. The view loops through the @posts by sending the "each" method to the 
array object provided by the controller.

We now live in the happy land of MVC. The controller coordinates all 
communication between the model layer and the view layer. The view and 
model have no direct knowledge of each other.

<% @posts.each do |post| %>
 <tr>
    <td><%= post.name %></td>
    <td><%= post.title %></td>
    <td><%= post.content %></td>
    <td><%= link_to 'Show', post %></td>
    <td><%= link_to 'Edit', edit_post_path(post) %></td>
    <td><%= link_to 'Destroy', post, :confirm => 'Are you sure?',
              :method => :delete %></td>
  </tr>
<% end %>

Even this is often considered to be too much logic for the view, so next 
it's time to clean things up by factoring out the rendering of the 
collection to a partial.

Read this for further explanation:

http://guides.rubyonrails.org/getting_started.html...

> What I wanted to accomplish is
> 1. in the select_tag I have added the  "include_blank=true" to allow
> user
> to add a value. it sisn't work for me. May i know what I did wrong
> 2. I am not getting the component_id value in the controller. Not sure
> what
> I did wrong
>   $selected_comp_id = Components.find(:all, :select => ['component_id'],
> :condition => ["component_name = '#{$selected_comp}'"])
>                 puts "selectd_comp_id is #{$selected_comp_id}"

I'll defer any attempt to answer these questions until after you get a 
decent grasp of the fundamentals. I'd suggest you do the same.