undefined method `macro' for nil:NilClass

rubyonrails-talk
1

this error usually occurs when trying to mix 1st and 2nd order relationships in a single to_json call:

undefined method `macro' for nil:NilClass

Rails 3 has this way to support 2nd order relationships:

http://apidock.com/rails/ActiveRecord/Serialization/to_json

So I try to use it:

        @units = User.where(:id => params[:user_id]).first.units.to_json(:include => {         :only => :reports,         :notifications => {:include => {:only => :notification_codes} }         })

A unit has many reports and notifications. And a notification belongs to notification code.

This is the relationship between notifications and notification codes:

//notifications   belongs_to :notification_code, :foreign_key => :code

//notification codes   has_many :notifications

So I am not sure why error occurs.

Thanks for response

2

Hi!

The call to to_json shouldn’t be the last call in the statement?

Regards,

Everaldo

3

It was working fine until I added the 2nd order relationship. The documentation isnt clear about how to add the 2nd order relationship

4

this error usually occurs when trying to mix 1st and 2nd order relationships in a single to_json call:

undefined method `macro' for nil:NilClass

Rails 3 has this way to support 2nd order relationships:

to_json (ActiveRecord::Serialization) - APIdock

So I try to use it:

    @units = User\.where\(:id =>

params[:user_id]).first.units.to_json(:include => { :only => :reports, :notifications => {:include => {:only => :notification_codes} } })

A unit has many reports and notifications. And a notification belongs to notification code.

There is an example of second order include & only on the page you link to. You're using :only to refer to association names whereas only is supposed to denote which attributes you want to show for a given object so i think you are confusing to_json. something like :include => {:reports, :notifications => :notification_codes} should do the trick.

Fred

:include => {:notifications, :only => :reports, :include => {:

5

thanks for response

THis here would produce syntax error:

:include => {:reports, :notifications => :notification_codes}

So I try this (to ensure :reports has a value):

{:include => {:reports => {}, :notifications => :notification_codes}}

And this is ultimately what it would look like:

User.where(:id => params[:user_id]).first.units.to_json({:include => {:reports => {}, :notifications => :notification_codes}})

But this will say:

can't convert Symbol into Hash

6

thanks for response

THis here would produce syntax error:

:include => {:reports, :notifications => :notification_codes}

oops, that should have been [:reports, {:notifications => :notification_codes}]

also, if notification belongs_to :notification code, then it should be

[:reports, {:notifications => :notification_code}]

i.e. the symbols in that hash should exactly match the name given to the has_many, belongs_to etc.

Fred

7

Frederick Cheung wrote in post #1032161:

thanks for response

THis here would produce syntax error:

:include => {:reports, :notifications => :notification_codes}

oops, that should have been [:reports, {:notifications => :notification_codes}]

also, if notification belongs_to :notification code, then it should be

[:reports, {:notifications => :notification_code}]

i.e. the symbols in that hash should exactly match the name given to the has_many, belongs_to etc.

Fred

thanks for response,

this is what ultimately worked for me:

Unit.where(:id => params[:unit_id]).first.reports.to_json(:include => { :notifications => {                                          :include => { :notification_code => {                                                        :only => :name } }                                                       } }) As you mentioned, this would only include the "name" attribute of notification code, but anything else I tried was still giving the "macro" error.