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