Understanding Variables in Rails?

Question

Ruby on Rails

Stumbled upon a problem while trying to put objects with certain qualities into variables
tasks_controller.rb:
(Rails 4)

def index
@incomplete_tasks = Task.find_by(status: 0)
@completed_tasks = Task.find_by(status: 1)
end

index.html.erb:

<% @incomplete_tasks.each do |task| %>
...
<% end %>

Throws an error undefined method `each' for #<Task:0x007fbf850f0db0>
With the banal @tasks = Task.all everything works as it should
. What's the catch?

Answer 1

find_byreturns a single record either nil
Try, for example, Task.where(status: 0)

Answer 2

And use named scopes.
scope :completed, -> { where(status: 1) }
scope :incompleted, -> { where(status: 0) }
And access them: Task.completed, Task.incompleted

Answer 3

find_by returns one entry, each does not. You need to do this:

@incomplete_tasks = Task.where(status: 0)
@completed_tasks = Task.where(status: 1)