Rails nested Attributes of join table won't be saved - ruby-on-rails

Question

Nested attributes of join model won't be saved. relation id's seems to be missing. The following error messages are added when the fields get validated:
* Assigned projects user can't be blank
* Assigned projects project can't be blank
The submitted params look like this ( <%= debug(params) %> )
--- !map:ActionController::Parameters
utf8: "\xE2\x9C\x93"
authenticity_token: HrF1NHrKNTdMMFwOvbYFjhJE1ltlKbuz2nsfBYYBswg=
project: !map:ActionController::Parameters
name: Peter Pan
assigned_projects_attributes: !map:ActiveSupport::HashWithIndifferentAccess
"0": !map:ActiveSupport::HashWithIndifferentAccess
position: Group Leader
currency: " Neverland Dollars"
commit: Add Project
action: create
controller: projects
I have 3 models, as followed:
class User < ActiveRecord::Base
has_many :assigned_projects
has_many :projects, :through => :assigned_projects
has_many :created_projects, :class_name => "Project", :foreign_key => :creator_id
end
class AssignedProject < ActiveRecord::Base
belongs_to :user, class_name: "User"
belongs_to :project, class_name: "Project"
attr_accessible :project_id, :user_id, :position, :project_attributes
accepts_nested_attributes_for :project
validates :user_id, presence: true
validates :project_id, presence: true
validates :position, presence: true
end
class Project < ActiveRecord::Base
belongs_to :user
has_many :assigned_projects
has_many :users, :through => :assigned_projects
belongs_to :creator, :class_name => "User", :foreign_key => :creator_id
attr_accessible :name, :creator_id, :currency :assigned_projects_attributes
accepts_nested_attributes_for :assigned_projects
validates :name, presence: true, length: { minimum: 3, maximum: 100 }
validates :currency, presence: true, length: { minimum: 1, maximum: 5 }
validates :creator_id, presence: true
end
So each User can create a Project. He can add any User to the Project through the join model.
Each Project belongs to a User resp. Creator and has_many user through assigned_projects
I want to give each user of a project a "position", which should be saved in the join model: assigned_project :position
the Project controller looks like that:
class ProjectsController < ApplicationController
def new
#project = Project.new
#project.assigned_projects.build(user_id: current_user)
end
def create
#project = current_user.assigned_projects.build.build_project(params[:project])
#project.creator = current_user
if #project.save
redirect_to current_user
else
render 'new'
end
end
end
and the project/new.html.erb form looks like that:
<%= form_for( #project ) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<%= f.label :name %>
<%= f.text_field :name %>
<%= f.fields_for :assigned_projects do |ff| %>
<%= ff.label :position %>
<%= ff.text_field :position%>
<% end %>
<%= f.label :currency %>
<%= f.text_field :currency %>
<%= f.submit "Add Project", class: "" %>
<% end %>
UPDATE: current controller & view
def create
#project = Project.new(params[:project])
if #project.save
redirect_to current_user
else
render 'new'
end
end
<%= form_for( #project ) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<%= f.label :name %>
<%= f.text_field :name %>
<%= f.hidden_field :creator_id, value: current_user.id %>
<%= f.fields_for :assigned_projects, #project.assigned_projects do |ff| %>
<%= ff.label :position %>
<%= ff.text_field :position%>
<% end %>
<%= f.label :currency %>
<%= f.text_field :currency %>
<%= f.submit "Add Project", class: "" %>
<% end %>

Answer 1

View:
I think you need to pass the objects collection #project.assigned_projects you built in the new action to the fields_for:
<%= render 'shared/error_messages', object: f.object %>
<%= f.label :name %>
<%= f.text_field :name %>
<%= f.fields_for :assigned_projects, #project.assigned_projects do |ff| %>
<%= ff.label :position %>
<%= ff.text_field :position%>
<% end %>
<%= f.label :currency %>
<%= f.text_field :currency %>
<%= f.submit "Add Project", class: "" %>
Controller:
If i understood the first line in the create action i think you try to re-build the project assigned_projects in-order to stamp the creator attribute !!
Instead you could remove this line and put a hidden field in the nested for, something like:
<%= ff.hidden_field :creator, current_user %>
So your controller looks pretty basic now:
def create
#project = Project.new(params[:prject])
if #project.save #nested objects will be saved automatically
redirect_to current_user
else
render 'new'
end
end

Answer 2

What does the build_project method do?
I think in your controller you should just have build, not build.build_project, so like this:
#project = current_user.assigned_projects.build(params[:project])
of if build_project is a method used to create the params then
#project = current_user.assigned_projects.build(project_params)
in the case of rails 4 you would need something like this:
def project_params
params.require(:project).permit(:your_params)
end
In the case of rails 3 I think you need to add
attr_accessible :param1, :param2
in the project model for the parameters you want to set.

Answer 3

Problem is solved by removing the validations for project_id and user_id in the join table "AssignedProject"
So the join Model looks like that:
# Join Model AssignedProject
class AssignedProject < ActiveRecord::Base
belongs_to :user#, class_name: "User"
belongs_to :project#, class_name: "Project"
attr_accessible :project_id, :user_id, :position, :project, :project_attributes
accepts_nested_attributes_for :project
validates :position, presence: { message: " can't be blank." }
end
The New and Create methods look like that:
# Projects Controller
class ProjectsController < ApplicationController
def new
#project = Project.new
#project.assigned_projects.build(user_id: current_user)
end
def create
#project = Project.new(params[:project])
if #project.save
#project.assigned_projects.create(user_id: current_user)
redirect_to current_user
else
render 'new'
end
end
end
And the form in the view for the new method looks like that:
<%= form_for( #project ) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<%= f.label :name %>
<%= f.text_field :name %>
<%= f.hidden_field :creator_id, value: current_user.id %>
<%= f.fields_for :assigned_projects, #project.assigned_projects do |ff| %>
<%= ff.hidden_field :project_id, value: #project %>
<%= ff.hidden_field :user_id, value: current_user.id %>
<%= ff.label :position %>
<%= ff.text_field :position%>
<% end %>
<%= f.label :currency %>
<%= f.text_field :currency %>
<%= f.submit "Add Project", class: "" %>
<% end %>