I am attempting to tie a Project to Projectparts to Parts and I
believe the relationship should be one-to-many, then many-to-one. My
goal is to build the Parts table so that this table can grow and the
Parts descriptions can be re-used in different Projects (ultimately
tie this in to an autocomplete plug-in so the user doesn''t have to re-
type a part every time, but I''m not there yet). I had the application
working through to the Project - Projectparts relationship, I am now
trying to add the description component from the Part table.
I think I''ve tracked down my problem to the _projectpart partial of
code that I''ve implemented for this. Here''s the partial:
<div class="fields">
<%= f.text_field :qty, :size => 3 %>
<% f.fields_for :parts do |builder| %> # <======I think
problem is here.
<%= builder.text_field :description, :size => 50 %>
<% end %>
<%= remove_child_link "Delete", f %>
</div>
As the code is now, the ''New'' view will render, but when I
save the
data from the UI, I get an unknown attribute error in my
''Create'':
ActiveRecord::UnknownAttributeError in ProjectsController#create
unknown attribute: parts
However, when I change the :parts reference to :part, the New screen
will not render & I get a nil object error:
NoMethodError in Projects#new
Showing app/views/projects/_projectpart.html.erb where line #10
raised:
You have a nil object when you didn''t expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.new_record?
So I''m thinking I''m not referencing this correctly.
I''ve tried using
@project.projectpart.description, @project.projectpart & other
variations, but not sure if the model is set up correctly in the first
place (the description is the ''one'' at the end of the
one-to-many /
many-to-one relationship).
Any thoughts? Thanks in advance.
For reference:
=======================Models:
class Project < ActiveRecord::Base
validates_presence_of :name
has_many :projectparts, :dependent => :destroy
accepts_nested_attributes_for :projectparts, :reject_if => lambda
{ |a| a.values.all?(&:blank?) }, :allow_destroy => true
def projectpart_attributes=(projectpart_attributes)
projectpart_attributes.each do |attributes|
projectpart.build(attributes)
end
end
end
class Projectpart < ActiveRecord::Base
belongs_to :project
has_one :part
accepts_nested_attributes_for :parts, :reject_if => lambda { |a|
a.values.all?(&:blank?) }
end
class Part < ActiveRecord::Base
has_and_belongs_to_many :projectparts
end
My db schema - the foreign key for accessing the Part description is
in the projectparts table since there should be many of these records
and I don''t want to unnecessarily increase the number of records in
the Parts table, but perhaps this is causing part of the problem?
create_table "projects", :force => true do |t|
t.string "name"
t.string "description"
end
create_table "projectparts", :force => true do |t|
t.integer "project_id"
t.integer "part_id"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "qty"
end
create_table "parts", :force => true do |t|
t.string "description"
t.datetime "created_at"
t.datetime "updated_at"
end
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