Self Referential HABTM Checkbox Example or Tutorial Needed

Rails
1

My checkboxes currently show up either checked or not checked based on
manually entered data using this bit so far…

<% Project.find(:all).each do |project| %>
<input type=“checkbox” id="<%= project.id %>" name=“project_ids[]”
value="<%= project.id %>"<% if @project.cross_reference.include? project
%> checked=“checked”<% end %>> <%= project.name %>

I have projects that relate to other projects in a cross_reference table
with rows for project_id and cross_reference_id.

My manually enter values can be retrieved but I can’t figure out how to
write the values to the cross_reference table from a web form.

Any reference or guidance appeciated.

Thanks,
DAN

2

Just a suggestion: use has_many :through instead. habtm is kinda
deprecated, at least partly.

3

I dunno if this helps you, but in HowTo:
http://wiki.rubyonrails.com/rails/pages/Howtos
you will find a document about many to many relations.

Besides, in
http://www.fallenrogue.com/article/view/143-I-am-what-I-am-or-self-referential-joins-in-Rails
you will find an example on self-referential joins…

4

Thanks for the direction.

I’ve added a cross_reference model now and in my
models/cross_reference.rb is

has_many :projects
belongs_to :project

and my models/project.rb contains

has_many :cross_references
has_many :projects, :through => :cross_references

I’m able to show manually entered data, such as discriminaing which
checkboxes for related projects should be checked - same as before, but
now using the code in my project form partial

<% Project.find(:all).each do |project| %>
<input type=“checkbox” id="<%= project.id %>" name=“project_ids[]”
value="<%= project.id %>"<% if @project.projects.include? project %>
checked=“checked”<% end %>> <%= project.name %>

<% end %>

I’m still stuck on trying to save (via my project edit or update
methods) to my cross_references table though.

I believe I need some statements in my project_controller.rb new,
create, and update methods such as:

def project_new
@project = Project.new
@cross_references = CrossReference.find(:all)
end

def project_create
@project = Project.new(params[:project])
@project.cross_references =
CrossReference.find(@params[:cross_reference_ids]) if
@params[:cross_reference_ids]
end

def project_edit
@project = Project.find(params[:id])
@cross_references = CrossReference.find(:all)
end

def project_update
@project = Project.find(params[:id])
@project.cross_references =
CrossReference.find(@params[:cross_reference_ids]) if
@params[:cross_reference_ids]
end

I hope I’m poviding enough information. It would be great to understand
how the create these kind of relationships.

DAN