Error of undefined method

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Yennie

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Jun 20, 2011, 12:33:15 PM6/20/11
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Hi all, I have very basic error that i have no idea how to show

I have user table
id
name
add
phone number


then i select all in user table
using => @users = User.all

=> @users.name

it gives me undefined method name Array<.....>

Please give me some advice..


Thanks

Tom Meinlschmidt

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Jun 20, 2011, 12:37:08 PM6/20/11
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@users.all basically returns "array" of users

so you have to iterate through this array

@users.each do |user|
puts user.name
end

tom

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Everaldo Gomes

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Jun 20, 2011, 12:38:39 PM6/20/11
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Hi!

The method User.all returns an Array of users, not a single user.

I think you have to iterate over the array, using each.

@users.each { |u| u.name }

Everaldo

joanne ta

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Jun 20, 2011, 12:48:52 PM6/20/11
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thanks
--
--------------------------------

Thank you,

Yen

joanne ta

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Jun 20, 2011, 12:53:50 PM6/20/11
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I have other undefined method when i combine the code above together

<%@users = User.all%>
<%@users.each do |u|%>
<%u.culture_id%>

 <% @pic= Picture.where(:phrase_id => :route , :culture_id => u.culture_id).first%>
    <td>My picture <%= @pic.image%></td>

and it causes undefined method image

please give me advices.... thank you so much


Joanne



On Mon, Jun 20, 2011 at 12:48 PM, joanne ta <joann...@gmail.com> wrote:
thanks

On Mon, Jun 20, 2011 at 12:38 PM, Everaldo Gomes <everald...@gmail.com> wrote:
Hi!

The method User.all returns an Array of users, not a single user.

I think you have to iterate over the array, using each.

@users.each { |u| u.name }

Everaldo


On Mon, Jun 20, 2011 at 1:33 PM, Yennie <joann...@gmail.com> wrote:
Hi all, I have very basic error that i have no idea how to show

I have user table
id
name
add
phone number


then i select all in user table
using => @users = User.all

=> @users.name

it gives me undefined method name Array<.....>

Please give me some advice..


Thanks

Joanne

Colin Law

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Jun 20, 2011, 2:42:14 PM6/20/11
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On 20 June 2011 17:53, joanne ta <joann...@gmail.com> wrote:
> I have other undefined method when i combine the code above together
>
> <%@users = User.all%>
> <%@users.each do |u|%>
> <%u.culture_id%>
>
>  <% @pic= Picture.where(:phrase_id => :route , :culture_id =>
> u.culture_id).first%>
>     <td>My picture <%= @pic.image%></td>
>
> and it causes undefined method image

What does it say has not got a method image? It is always a good idea
to post the complete error message (use copy/paste rather than
re-typing it). If it says the nil has not got the method then your
call of Picture.where has not found a record.

Colin

joanne ta

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Jun 20, 2011, 3:08:32 PM6/20/11
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the error is undefined method `image' for nil:NilClass


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Thank you,

Yen

Chris Kottom

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Jun 20, 2011, 3:33:13 PM6/20/11
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You don't have an <% end %> to close the <% @users.each %> block in the code you included, so my guess is that your u variable is already out of scope by the time you call u.image.

Colin Law

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Jun 21, 2011, 3:23:16 AM6/21/11
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On 20 June 2011 20:08, joanne ta <joann...@gmail.com> wrote:

Please don't top post, it makes it difficult to follow the thread.
Insert your reply at appropriate places in previous message. Thanks.

> the error is undefined method `image' for nil:NilClass

So what does that mean (see my previous post)?

Colin

Chirag

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Jun 21, 2011, 4:11:55 AM6/21/11
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Hi,

Few things here:
1. Would be good if you can paste full code from the beginning of the loop till the place where you render picture
2. It is not a good practice to set instance variables in the views, set them in controller instead
3. It is not a good practice to do finds in views, if you want to fetch a picture for the user, it's better to define a relationship between picture and user models. And then do something like this in the controller - @users = User.includes(:picture).all

Hope this helps.

joanne ta

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Jun 21, 2011, 9:47:26 AM6/21/11
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My controller:

 
  def index
   @users= User.all
   
    @users.each do |p|   
    @pic= Picture.where(:phrase_id => :route , :culture_id => p.culture_id).first
     send_data @pic.image, :type => 'image/gif', :disposition => 'inline'
    end
end

in View

  <tr width = "50%">
 <td><%= image_tag url_for(:controller => "/users", :action => "index"), :width => "25px", :height => "25px"%></td>

<%@pic.each do |c|%>
  <%= c.image%>
<% end %>


please give me some advices..


thanks
Joanne

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joanne ta

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Jun 21, 2011, 9:52:23 AM6/21/11
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My controller:

 
  def index
   @users= User.all
   
    @users.each do |p|   
    @pic= Picture.where(:phrase_id => :route , :culture_id => p.culture_id).first
     send_data @pic.image, :type => 'image/gif', :disposition => 'inline'
    end
end

in View

  <tr width = "50%">
 <td><%= image_tag url_for(:controller => "/users", :action => "index"), :width => "25px", :height => "25px"%></td>

<%@pic.each do |c|%>
  <%= c.image%>
<% end %>

error is
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each


Extracted source (around line #79):

76:   <tr width = "50%">
77:  <td><%= image_tag url_for(:controller => "/users", :action => "index"), :width => "25px", :height => "25px"%></td>
78:
79: <%@pic.each do |c|%>
80:   <%= c.image%>
81: <% end %>
82: 




Chirag Singhal

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Jun 21, 2011, 9:57:50 AM6/21/11
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Your index action should be something like this:

def index
  @users= User.all
  @pic = []
 
  @users.each do |p|    
    @pic << Picture.where(:phrase_id => :route , :culture_id => p.culture_id).limit(1)
  end
end

joanne ta

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Jun 21, 2011, 10:12:29 AM6/21/11
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it does not work, it is complaining other error

NoMethodError (undefined method `image' for [nil]:Array):
  app/controllers/patients_controller.rb:27:in `block in index'
  app/controllers/patients_controller.rb:25:in `each'
  app/controllers/patients_controller.rb:25:in `index'
 

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Chirag Singhal

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Jun 21, 2011, 10:27:14 AM6/21/11
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Oh yes... sorry about that.
I assumed that you will find picture for every query.

You can try this instead:
def index
  @users= User.all
  @pic = []
 
  @users.each do |p|    
    @pic << Picture.where(:phrase_id => :route , :culture_id => p.culture_id).limit(1)
  end
  @pic.compact!
end

by calling compact! on the array, we will eliminate all nil object.

On another note, are you sure, this is what you want to do? If you have 100 users, it will fire 100 sql queries which is not good.

joanne ta

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Jun 21, 2011, 10:40:17 AM6/21/11
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On Tue, Jun 21, 2011 at 10:27 AM, Chirag Singhal <chirag....@gmail.com> wrote:
Oh yes... sorry about that.
I assumed that you will find picture for every query.

You can try this instead:
def index
  @users= User.all
  @pic = []
 
  @users.each do |p|    
    @pic << Picture.where(:phrase_id => :route , :culture_id => p.culture_id).limit(1)
  end
  @pic.compact!
end

by calling compact! on the array, we will eliminate all nil object.

On another note, are you sure, this is what you want to do? If you have 100 users, it will fire 100 sql queries which is not good.

Yes i think i have that problem as well because if i remove  "@users.each do |p|    "
and then it will cause undefined method of culture_id..
plus when i call @pic.compact! , it gives me 

NoMethodError (You have a nil object when you didn't expect it!

You might have expected an instance of Array.
The error occurred while evaluating nil.compact!):
  app/controllers/patients_controller.rb:29:in `index'

what is mean? cuz i want to display picture on the browser too...

please help... thank you very much

Joanne

Chirag Singhal

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Jun 21, 2011, 10:56:58 AM6/21/11
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Can you paste what you have in your index method?
You should not be getting this error because we have already defined @pic as an empty array.

joanne ta

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Jun 21, 2011, 11:05:21 AM6/21/11
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Can you paste what you have in your index method?
You should not be getting this error because we have already defined @pic as an empty array.
 
 
def index
    @users= User.all
    @pic= []
   
    @users.each do |p|   
    @pic<< Picture.where(:phrase_id => :route , :culture_id => p.culture_id).first

    end
   
    @pic.compact!
    send_data @pic.image, :type => 'image/png', :disposition => 'inline'
    
  end




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Thank you,

Yen

Chirag Singhal

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Jun 21, 2011, 11:28:40 AM6/21/11
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1. Remove the send_data line, it isn't required.
2. Can you check if there are any records in your pictures table? Right now it looks like it is returning nil.

joanne ta

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Jun 21, 2011, 11:31:54 AM6/21/11
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>> def index
>>     @users= User.all
>>     @pic= []

You would probably have fewer problems if you observed the Rails
naming conventions;  e.g.

@pictures = []  # plural

@users.each do |user|
    @pictures << Picture.where(:phrase_id => :route , :culture_id
=>user.culture_id).first
end

@pictures.compact!

Now it's obvious that the next line makes no sense:

        send_data @pictures.image, :type => 'image/png', :disposition
=> 'inline'

An *array* of pictures doesn't have an "image" attribute.

because i want to take a value "image" from Picture model
what can i do ... I am really stuck now..

thanks


Joanne
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twitter: @hassan

joanne ta

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Jun 21, 2011, 11:35:21 AM6/21/11
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1. Remove the send_data line, it isn't required.
Yes, it did remove it.
2. Can you check if there are any records in your pictures table? Right now it looks like it is returning nil.
Yes, It has 1 record in Picture table and 3 records in User Table
 

Colin Law

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Jun 21, 2011, 11:36:49 AM6/21/11
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On 21 June 2011 16:31, joanne ta <joann...@gmail.com> wrote:
> ...

> what can i do ... I am really stuck now..

I think it might be a good idea for you to work through some Rails
tutorials to understand the basics of Rails. The free-to-use-online
tutorial railstutorial.org is good. It might seem that the tutorial
does not lead to the application that you want to develop but if you
work right through it you will learn a vast amount and will then be
embarrassed to look back here at the questions you were asking :)

Also take a good look at the Rails Guides. I mean a *good* look do
not just skim through them. Again you will learn a lot and the time
spent will be saved many times over.

Colin

Chirag Singhal

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Jun 21, 2011, 11:46:31 AM6/21/11
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Not sure why it errors out now.
Do you get the same error is it a different error this time?

joanne ta

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Jun 21, 2011, 11:52:07 AM6/21/11
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Not sure why it errors out now.
Do you get the same error is it a different error this time?

this is my index

  def index
    @user= Users.all
    @pictograph = []
   
    @user.each do |p|   
    @pic= Picture.where(:phrase_id => :route , :culture_id => p.culturet_id).first
    @pic.compact!
     end
  end

and my view is

<td><%= image_tag url_for(:controller => "/users", :action => "index"), :width => "25px", :height => "25px"%></td>

my error:
  Processing by UsersController#index as
  User Load (1.0ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
  PictureLoad (7.0ms)  SELECT "pictures".* FROM "pictures" WHERE "pictures"."phrase_id" = 'route' AND "pictures"."culturet_id" = 1 LIMIT 1
Completed   in 237ms


NoMethodError (You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.compact!):
  app/controllers/users_controller.rb:27:in `block in index'
  app/controllers/users_controller.rb:25:in `each'
  app/controllers/users_controller.rb:25:in `index'

Chirag Singhal

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Jun 21, 2011, 11:59:23 AM6/21/11
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Oh, so you are trying to get the image url from the user's index action?
If yes, that's not correct.

You should instead have a different method name and should request for image url of only one specific user.

It would help in cleaning up the code and solve this issue faster, if you can tell me what exactly you are trying to do.

joanne ta

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Jun 21, 2011, 12:07:29 PM6/21/11
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Oh, so you are trying to get the image url from the user's index action?
If yes, that's not correct.
yes, i am trying to get image url from db

You should instead have a different method name and should request for image url of only one specific user.
I have def show to get specific user

  def show 
    @user= User.find_by_id(params[:id])  
  end

It would help in cleaning up the code and solve this issue faster, if you can tell me what exactly you are trying to do.

I want take a value image from Picture table with specific user and display it on the screen.
can u help me... thanks :X so much much..


Joanne

Hassan Schroeder

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Jun 21, 2011, 11:25:09 AM6/21/11
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On Tue, Jun 21, 2011 at 8:05 AM, joanne ta <joann...@gmail.com> wrote:

>> def index
>>     @users= User.all
>>     @pic= []

You would probably have fewer problems if you observed the Rails
naming conventions; e.g.

@pictures = [] # plural

@users.each do |user|
@pictures << Picture.where(:phrase_id => :route , :culture_id
=>user.culture_id).first
end

@pictures.compact!

Now it's obvious that the next line makes no sense:

    send_data @pictures.image, :type => 'image/png', :disposition
=> 'inline'

An *array* of pictures doesn't have an "image" attribute.

HTH,

Chirag Singhal

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Jun 21, 2011, 12:15:07 PM6/21/11
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Ok, that's clear now.

Do you use pastie (http://pastie.org/) or gist (https://gist.github.com/)?
If yes, can you paste following on any of them and reply with link?

#models
User
Picture

#controllers
UsersController

#views
users/index

joanne ta

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Jun 21, 2011, 12:31:39 PM6/21/11
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Ok, that's clear now.

Do you use pastie (http://pastie.org/) or gist (https://gist.github.com/)?
If yes, can you paste following on any of them and reply with link?
No, I am using that..

 
#models
User
id
name
address
culture_id

Picture
id
image(binary)
phrase_id
culture_id

Culture
id
phrase_id

 

#controllers
UsersController
 
 def index
    @user= User.all
    @pic= []
    @user.each do |p|   
    @pic<< Picture.where(:phrase_id => :route , :culture_id => p.culture_id).first
     @pic.compact!

     end
  end


 
 

  def show 
    @user= User.find_by_id(params[:id])  
  end

end
 

#views
users/index
 
 <td><%= image_tag url_for(:controller => "/patients", :action => "index"), :width => "25px", :height => "25px"%></td>

joanne ta

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Jun 21, 2011, 12:34:40 PM6/21/11
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joanne ta

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Jun 21, 2011, 12:36:20 PM6/21/11
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Ok, that's clear now.

Do you use pastie (http://pastie.org/) or gist (https://gist.github.com/)?
If yes, can you paste following on any of them and reply with link?
No, I am not using that..

Chirag Singhal

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Jun 21, 2011, 12:52:05 PM6/21/11
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Ok, some more questions:
1. So, you want to display an image of the culture associated with the user, right?
2. How are you uploading pictures to your database?

joanne ta

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Jun 21, 2011, 1:11:39 PM6/21/11
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On Tue, Jun 21, 2011 at 12:52 PM, Chirag Singhal <chirag....@gmail.com> wrote:
Ok, some more questions:
1. So, you want to display an image of the culture associated with the user, right?
yes
2. How are you uploading pictures to your database?
right now, i just using the sqlite manager to upload the blob.
 

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Chirag Singhal

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Jun 21, 2011, 1:29:31 PM6/21/11
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Getting pretty late here, heading to bed. We can work on a cleaner solution tomorrow or others on the forum can help.
For now, this quick and dirty solution should work:

# In your view
<% @users.each do |user| %>
<td><%= user.name %></td>
<td><%= image_tag url_for(:controller => "users", :action => "culture_image, :culture_id => user.culture_id, :phrase_id => ""), :width => "25px", :height => "25px"%></td>

<% end %>

Note that I haven't put in a value for :phrase_id in the url, please substitute appropriate value there as required.

# In your controller
 def index
    @user= User.all
 end

 def culture_image
   picture = Picture.where(:phrase_id => params[:phrase_id], :culture_id => params[:culture_id]).limit(1)
   if picture
     send_data picture.image, :type => 'image/png', :disposition => 'inline'
   else
     render :status => 404
   end
 end

Note that you may have to modify your routes to include the new method "culture_image"... something like this"
resources :users do
  get :culture_image, :on => :collection
end

joanne ta

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Jun 21, 2011, 1:32:16 PM6/21/11
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thanks you so much..
Joanne

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Chirag Singhal

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Jun 22, 2011, 12:00:55 AM6/22/11
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Is it working now?
If not post the error and we'll see how to get it to a good shape.
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