Associations in Rails 4 - ruby-on-rails

Question

I am developing a web application for task management using ruby on rails.
I have two models user and task. The models look like this
class User < ActiveRecord::Base
has_many :tasks
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
def role?(role_name)
role == role_name
end
def self.assigned_user(task_params)
User.where("name = ?", task_params["assigned_to"])
end
end
class Task < ActiveRecord::Base
belongs_to :user
end
what i want is assign task to user when a task is created. But i don't know how to do it in create action of tasks_controller. My create action looks like this
def create
#task = Task.new(task_params)
respond_to do |format|
if #task.save
#user = User.assigned_user(task_params)
#user.tasks << Task.last
format.html { redirect_to #task, notice: 'Task was successfully created.' }
format.json { render :show, status: :created, location: #task }
else
format.html { render :new }
format.json { render json: #task.errors, status: :unprocessable_entity }
end
end
end
Whenever admin assigns a task when its created, it gives an error saying undefined method tasks for #<User::ActiveRecord_Relation:0x007fe7b1c60610>. Does anyone can help what can be the problem with this?

Answer 1

The error it is giving you is because the where method is returning a collection of users and you want just one user:
def self.assigned_user(task_params)
User.where("name = ?", task_params["assigned_to"]).first
end
You probably want to revise your code as I guess you could have problems if name is not unique. Make sure the field you use to retrieve the user is unique.
The code for creation can look like this:
def create
#task = Task.new(task_params)
respond_to do |format|
if #task.save
#user = User.assigned_user(task_params)
#user.tasks << #task
format.html { redirect_to #task, notice: 'Task was successfully created.' }
format.json { render :show, status: :created, location: #task }
else
format.html { render :new }
format.json { render json: #task.errors, status: :unprocessable_entity }
end
end
end

Answer 2

Well the error, speaks for itself:
undefined method tasks for User::ActiveRecord_Relation:0x007fe7b1c60610>
def self.assigned_user(task_params)
User.where("name = ?", task_params["assigned_to"])
end
where method returns an array(ActiveRecord_Relation), then since you need only to fetch one object, it shoud be:
User.where(name: task_params["assigned_to"]).first
or even better:
User.find_by(name: task_params["assigned_to"])
Also this line:
#user.tasks << Task.last
Will do a query in database unnecessarily.
So it should be changed to:
#user.tasks << #task
Hope it helps!!