Making ActiveResource work with nested attributes and fields_for

Rails
1

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.

2

Realy? No one?
Maybe here is not the place to ask such things. I’ll try somewhere else.

3

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

4

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

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

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.

5

On Tue, Feb 21, 2012 at 3:02 PM, Dimas C.
[email protected]wrote:

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

]
parameters in a strange way. He turns the ‘members_attributes: […]’ in

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.

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 member name some instrument

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
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

6

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.

7

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

8

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.

9

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.

  1. 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

10

On 3 March 2012 10:12, Anushank L. [email protected] 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

depends on Admin_user to give or take rights from PM.

–
You received this message because you are subscribed to the Google G. “Ruby
on Rails: Talk” group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

–
gplus.to/clanlaw