Betternestedset talk - Mar 2007 - Question about selecting a parent

Hi all,

I''m using the collection_select helper method in the partial
_form.rhtml
that is used in the edit.rhtml. When I edit an agent I want to be able 
to select a manager or no manager at all. In use the additional :prompt 
option like this:

<p><label
for="agent_parent_id">Manager</label><br/>
<%= collection_select("agent", "parent_id", @agents, :id,
:full_name,
{:prompt => "Select manager..."}, {:style => "width:
150px"}) %></p>

The @agents array comes from the edit action. Basically I retain all the 
current children of the agent and the agent itself because they can not 
be a manager:

  def edit
    @agent = Agent.find(params[:id])
    @agents = Agent.find_all_ordered - @agent.full_set
  end

The older Rails version always displayed the extra :prompt option. I use 
the following code after the save in my update action:

def update
    @agent = Agent.find(params[:id])
    if @agent.update_attributes(params[:agent])
      @agent.move_to_child_of(params[:agent][:parent_id])
...
end

If no manager was selected then the params[:agent][:parent_id] value is 
"". I can''t use it as the parameter for the move_to_child_of
method when
the agent would have no manager. I tried to use the :include_blank => 
true option but that gave me an exception:

Couldn''t find Agent with ID
I think it is because the extra blank option <option
value=""></option>
is becomes also a parameter with as value the empty string "":

*Parameters*: {"commit"=>"Edit",
"id"=>"1",
"agent"=>{"level_id"=>"4",
"identification"=>"BKU",
"product_id"=>"1",
"first_name"=>"Ben",
"last_name"=>"Kunnen",
"parent_id"=>""}}

The question is how do I select a manager (= the parent node) or none at 
all from a simple select box in my view and use the posted parent_id 
correctly in my actions?

Kind regards,

Mark Noten
Software engineer
ITFC gcv
E-mail: mark.noten at itfc.be
GSM: +32 (484) 698 333

Hi,

I see two possible solutions.

Le 20 mars 07, ? 22:15, Mark Noten a ?crit :
> I''m using the collection_select helper method in the partial 
> _form.rhtml
> that is used in the edit.rhtml. When I edit an agent I want to be able
> to select a manager or no manager at all. In use the additional :prompt
> option like this:
>
> <p><label
for="agent_parent_id">Manager</label><br/>
> <%= collection_select("agent", "parent_id", @agents,
:id, :full_name,
> {:prompt => "Select manager..."}, {:style => "width:
150px"}) %></p>
You could use select instead of collection_select and add your prompt 
associated with root:

<%= select(''agent'', ''parent_id'',
@agents.inject([[Agent.root.id,
''Select one...'']]){|all, an_agent| [[an_agent.id, 
an_agent.full_name]]}) %>

so your blank value would match the root of the tree and your node 
would be moved to be a level one child. (is it what you want ?)
> The older Rails version always displayed the extra :prompt option. I 
> use
> the following code after the save in my update action:
>
> def update
>     @agent = Agent.find(params[:id])
>     if @agent.update_attributes(params[:agent])
>       @agent.move_to_child_of(params[:agent][:parent_id])
> ...
> end
Second solution: test for empty parent_id here

def update
    @agent = Agent.find(params[:id])
    if @agent.update_attributes(params[:agent]) and 
!params[:agent][:parent_id].empty?
       @agent.move_to_child_of(params[:agent][:parent_id])

;-)

Jean-Christophe Michel
--
symetrie.com

Better Nested Set for rails:
http://opensource.symetrie.com/trac/better_nested_set