rails has_one relationship causing problems - also white screen

问题

I have two models: Schedule and Project. Schedule belongs_To Project and Project has_one schedule. There are several problems, but i think they all have the same cause. Here is the code for the schedules#create controller:

def create
            @schedule = Schedule.new(schedule_params)
            @schedule.project  = Project.find(params[:project_id])
            if @schedule.project.student_id == current_user.id
                if @schedule.save && @schedule.freelancer_accepts    
                        flash[:notice] = "Successfully created schedule."
                        redirect_to profile_path(current_user.profile_name)  
                else
                    render :action => 'new', :notice => 'Invalid Schedule'
                end
            else
                render :action => 'new', :notice => 'Schedule is invalid.'
            end
end

Here are the problems:

Even though it is a has_one relationship, I am still able to create many schedules for a single project. This led me to change my controller to this:

def create
    if !Schedule.where(project_id: params[:project_id]).any?
        @schedule = Schedule.new(schedule_params)
        @schedule.project  = Project.find(params[:project_id])
        if @schedule.project.student_id == current_user.id
            if @schedule.save && @schedule.freelancer_accepts     
                    flash[:notice] = "Successfully created schedule."
                    redirect_to profile_path(current_user.profile_name) 
            else
                render :action => 'new', :notice => 'Invalid Schedule'
            end
        else
            render :action => 'new', :notice => 'Schedule is invalid.'
        end
    else
        render :action => 'new', :notice => 'A schedule has already been created.'
    end
end

The change was that I essentially wrapped the controller in an if that says "if a schedule exists, don't create one. After I changed my code, I got the following problems:

In firefox, when I press the submit button to create a new schedule, i get this error:
```
First argument in form cannot contain nil or be empty
```
In Safari, when I press the submit button to create a new schedule, the page turns white. Furthermore, every time I try to go back to the page which displays the form, the page goes white. It is very strange.

How do I fix this? Thanks.

UPDATE: My routes and form view might help:

routes:

resources :projects do
  resources :schedules
end

First part of form:

<%= form_for [@project, @schedule] do |f| %>

回答1:

Turns out this and several other problems i was having was not actually caused by the has_one relationship. There was some type of problem with my cache. I'm not exactly sure what it was, but by disabling the cache I was able to fix the problem.

来源：https://stackoverflow.com/questions/20151104/rails-has-one-relationship-causing-problems-also-white-screen

标签

ruby-on-rails

model-view-controller

database-design

ruby-on-rails-4

has-one