Making ActiveResource work with nested attributes and fields_for

[Dimas Cyriaco]

Hello,

I'm trying to make ActiveResource work with nested attributes and the fields_for tag.

I started with a typical Rails application, with two ActiveRecord models with one to many relationship (one band has many members).

In view 'bands/new.html.erb' I have something like this:

<%= form_for @band do |f| %>

  <%= f.label: name %>

  <%= f.text_field: name %>

  <% f.fields_for: members do |member_form| %>

    <%= member_form.label: name %>

    <%= member_form.text_field: name %>

    <%= member_form.label: Instrument %>

    <%= member_form.text_field: Instrument %>

  <% end %>

 

  <%= f.submit >

<% end %>

In the controller I get this data as follows (in the params hash):

{

band: {

name: 'band name',

members_attributes: [

{name: 'member name' instrument: 'some instrument'}

]

}

}

When I send this params to ActiveRecord's new or create it creates the band and members. So far so good.

So I moved the ActiveRecord models into a service and replaced them with ActiveResource models.

However when I send the request to the service ActiveResource change these parameters in a strange way. He turns the 'members_attributes: [...]' in something like this:

members_attributes: [

    { members_attribute: { name: 'member name' instrument: 'some instrument' }}

]

And the ActiveRecord on the other side cannot treat this.

Does anyone have any idea how to prevent this behavior (or why it happens)?

In a second attempt I replaced the Band.create by Band.post(nil, {}, params[:band].to_json) (which makes a request directly to the service without going through the ActiveResource::Base#load that appears to be source of the problem), but ActiveResource does a post to '/bands/.json' instead of '/bands.json'. I patched ActiveResource's 'custom_method_collection_url' method, so the post goes to the right url, but i have not yet submitted a push request because I don't know if this will be usefull for everyone.

Actually I'm more concerned with understanding why ActiveResource's default behavior is so strange.

Anyone know what the purpose of the method ActiveRecord::Base#find_or_create_resource_for_collection? (I know what it does, i just don't understand why it does it). Wouldn't it be easier if ActiveResource simply passes my parameters for the service?

If someone can help me I would be grateful.

[Dimas Cyriaco]

Realy? No one?

Maybe here is not the place to ask such things. I'll try somewhere else.

[Esti Alvarez]

I'm having the same problem. Did you manage to solve it?

[Valery Kvon]

On 28.02.2012, at 19:34, Esti Alvarez wrote:

I'm having the same problem. Did you manage to solve it?

1) http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html

2) If nothing happens, customize view code:

"_member_fields.html.erb":

    <%= builder.label: name %>

    <%= builder.text_field: name %>

    <%= builder.label: Instrument %>

    <%= builder.text_field: Instrument %>

"_form.html_erb":

<% if @band.new_record? %>

  <% f.fields_for :members_attributes do |member_form| %>

      <%= render "member_fields, :builder => member_form %>

  <% end %>

<% else %>

  <% @band.members.each.with_index do |index, member| %>

   <% f.fields_for member, "members_attributes[#{index}]" do |member_form| %>

      <%= render "member_fields, :builder => member_form %>

   <% end %>

 <% end %>

<% end %>

I could write something inaccurate, but like that.

[Peter Vandenabeele]

Sorry, was a bit overloaded ...

What I did to accept XML input for such a case was:

* put back the "has_many" objects in an array of objects without the _attributes attachment.

The hash would then be:

{

band: {

name: 'band name',

members: [

{name: 'member name' instrument: 'some instrument'}

]

}

}

for XML that would be:

<band>
  <name>band name</name>
  <members type="array">
<name>
      member name
    </name>
    <instrument>
      some instrument
    </instrument>
  </members>
</band>

and similar for JSON.

Then to create a band and it's member with the assignment:

  band = Band.new(params[:band])

which needs a fix to the members= function in the Band class.

class Band
  # members
  has_many :members, :inverse_of => :band
  accepts_nested_attributes_for :members
  include Xml::FromXmlMembers
end

module Xml
  module FromXmlMembers
    extend ActiveSupport::Concern
    included do
      # for xml  (on band.members=)
      def members=(members)
        case members
        when Array
          super(
            members.map |member|
              case member
              when Hash
                Member.new(member)
              else
                member
              end
            end)
        else
          raise 'members MUST be an array; maybe <members type="array"> was forgotten'
        end
      end
    end
  end
end


The catch is that the function `members= ` that is created by the has_many
relationship
* expects an array of Member objects
* but the hash I typically got when parsing incoming XML data
  (and you seem to have here with ActiveResource)
is an array of attributes hashes.

HTH (not entirely sure ...),

Peter

[Mark Peterson]

Which version of ActiveResource are you using? I also encounter what you are encountering while using ActiveResource 3.2.1.

In 3.0.* there was "ActiveResource::Base.include_root_in_json" which you could set to false. I am not positive if that's the exact stumbling point, but it feels like it is.

[Mark Peterson]

There's a difference between ActiveModel 3.0.* and ActiveModel 3.2.*

ActiveModel 3.0.*
----------
module ActiveModel
  module Serializers
    module JSON
      def as_json(options = nil)
        hash = serializable_hash(options)

        if include_root_in_json
          custom_root = options && options[:root]
          hash = { custom_root || self.class.model_name.element => hash }
        end

        hash
      end
    end
  end
end

ActiveModel 3.2.*
----------
module ActiveModel
  module Serializers
    module JSON
      def as_json(options = nil)
        root = include_root_in_json
        root = options[:root] if options.try(:key?, :root)
        if root
          root = self.class.model_name.element if root == true
          { root => serializable_hash(options) }
        else
          serializable_hash(options)

        end
      end
    end
  end
end

I think this has something to do with it. Apologies if I set you on a wild goose chase.

[Mark Peterson]

Put a new file in your initializers with this code below and see if it helps:

module ActiveResource
  class Base
    self.include_root_in_json = false
  end 
  module Formats
    module JsonFormat
      def decode(json)
        ActiveSupport::JSON.decode(json)
      end
    end
  end
end

module ActiveModel
  module Serializers
    module JSON
      def as_json(options = nil)
        hash = serializable_hash(options)
        if include_root_in_json
          custom_root = options && options[:root]
          hash = { custom_root || self.class.model_name.element => hash }
        end
        hash
      end

      def from_json(json)
        hash = ActiveSupport::JSON.decode(json)
        hash = hash.values.first if include_root_in_json
        self.attributes = hash
        self
      end
    end
  end
end

[Anushank Lal]

I am creating application which requires User management of various
levels for authorization of different level of users.

I want several models:
Admin_user
Project Manager
Company
Clients
Account : have many users of all level.Every user have account.

See below the relations between our models:

1. Admin_user : have many project managers and can give rights to
project manager.It can add and delete Project managers.Admin can
access or manage any level of this application i.e. Its a SUPER USER.

2.Project manager : have many companies.It can create and delete many
companies. Project Manager can also add new project manager if
Admin_user give right to him to create new project manager.its all
depends on Admin_user to give or take rights from PM.

3. Companies : can create and delete many client_users but cannot
create any company in th same level.Company also start or stop rights
of client.

4.Client :can have account login and use services provided by company
nothing more than that.

This is my model Association. But i m confused what can i make first a
Account model or a Admin_user model.

Thanks

Attachments:
http://www.ruby-forum.com/attachment/7125/New_Text_Document.txt

--
Posted via http://www.ruby-forum.com/.

[Colin Law]

On 3 March 2012 10:12, Anushank Lal <li...@ruby-forum.com> wrote:
> I am creating application which requires User management of various
> levels for authorization of different level of users.
>
> I want several models:
> Admin_user
> Project Manager
> Company
> Clients
> Account : have many users of all level.Every user have account.

Don't have all those different models. Just have model User and use
Roles to limit capabilities of different user types. Have a look at
the cancan gem.

Colin

>
> See below the relations between our models:
>
> 1. Admin_user : have many project managers and can give rights to
> project manager.It can add and delete Project managers.Admin can
> access or manage any level of this application i.e. Its a SUPER USER.
>
> 2.Project manager : have many companies.It can create and delete many
> companies. Project Manager can also add new project manager if
> Admin_user give right to him to create new project manager.its all
> depends on Admin_user to give or take rights from PM.
>
> 3. Companies : can create and delete many client_users but  cannot
> create any company in th same level.Company also start or stop rights
> of client.
>
> 4.Client :can have account login and use services provided by company
> nothing more than that.
>
> This is my model Association. But i m confused what can i make first a
> Account model or a Admin_user model.
>
>
> Thanks
>
> Attachments:
> http://www.ruby-forum.com/attachment/7125/New_Text_Document.txt
>
>
> --
> Posted via http://www.ruby-forum.com/.
>

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--
gplus.to/clanlaw