Error of undefined method

Google_Mail · June 20, 2011, 4:33pm

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 · June 20, 2011, 4:37pm

@users.all basically returns "array" of users

so you have to iterate through this array

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

tom

Everaldo_Gomes · June 20, 2011, 4:38pm

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

Google_Mail · June 20, 2011, 4:48pm

thanks

Google_Mail · June 20, 2011, 4:53pm

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%> My picture <%= @pic.image%>

and it causes undefined method image

please give me advices… thank you so much

Joanne

thanks

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

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_Law1 · June 20, 2011, 6:42pm

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

Google_Mail · June 20, 2011, 7:08pm

the error is undefined method `image’ for nil:NilClass

Chris_Kottom1 · June 20, 2011, 7:33pm

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_Law1 · June 21, 2011, 7:23am

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 · June 21, 2011, 8:11am

Hi,

Few things here:

Would be good if you can paste full code from the beginning of the loop till the place where you render picture
It is not a good practice to set instance variables in the views, set them in controller instead
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.

Google_Mail · June 21, 2011, 1:47pm

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

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

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

please give me some advices…

thanks Joanne

Google_Mail · June 21, 2011, 1:52pm

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
<%= image_tag url_for(:controller => "/users", :action => "index"), :width => "25px", :height => "25px"%>
<%@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: 77: <%= image_tag url_for(:controller => “/users”, :action => “index”), :width => “25px”, :height => “25px”%>

78: 79: <%@pic.each do |c|%> 80: <%= c.image%> 81: <% end %> 82:

Chirag · June 21, 2011, 1:57pm

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

Google_Mail · June 21, 2011, 2:12pm

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’

Chirag · June 21, 2011, 2:27pm

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.

Google_Mail · June 21, 2011, 2:40pm

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 · June 21, 2011, 2:56pm

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.

Google_Mail · June 21, 2011, 3:05pm

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

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

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’

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

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hassan · June 21, 2011, 3:25pm

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 · June 21, 2011, 3:28pm

Remove the send_data line, it isn’t required.
Can you check if there are any records in your pictures table? Right now it looks like it is returning nil.

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