Ruby 上轨，Rubocop 重构

Question

Offenses:

app/controllers/tasks_controller.rb:12:3: C: Metrics/AbcSize: Assignment Branch Condition size for create is too high. [<3, 19, 1> 19.26/17] def create...

app/controllers/tasks_controller.rb:24:3: C: Metrics/AbcSize: Assignment Branch Condition size for update is too high. [<4, 20, 1> 20.42/17] def update...

27 files inspected, 2 offenses detected

  def create
    @task = current_user.projects.find(params[:project_id]).tasks.new
    @task.title = task_params[:title]

    @task.save ? (redirect_to root_url) : (flash[:error] = @task.errors.full_messages) | (render 
    :new)
  end

  def update
    @task = current_user.tasks.find(params[:id])
    @task.title = task_params[:title]
    @task.deadline = task_params[:deadline]

    @task.save ? (redirect_to root_url) : (flash[:error] = @task.errors.full_messages) | (render 
    :edit)
  end

How can i refactor it to resolve rubocop's offences?

Solved problem by creating private methods:

  def create
    tasknew
    tasktitle

    @task.save ? (redirect_to root_url) : (flash[:error] = @task.errors.full_messages) | (render :new)
  end

  def update
    taskfind
    tasktitle
    @task.deadline = task_params[:deadline]

    @task.save ? (redirect_to root_url) : (flash[:error] = @task.errors.full_messages) | (render :edit)
  end

private

  def tasktitle
    @task.title = task_params[:title]
  end

  def taskfind
    @task = current_user.tasks.find(params[:id])
  end

  def tasknew
    @task = current_user.projects.find(params[:project_id]).tasks.new
  end

Answer 1

You've extracted the simplest part of your code and left the most complex. The point of the ABC metric is to point out complex parts of your code so you can simplify them, and possibly catch bugs. If you just extract the most trivial parts to satisfy the cop, you might as well disable it.

@task.save? (redirect_to root_url): (flash[:error] = @task.errors.full_messages) | (render:edit) @task.save? (redirect_to root_url): (flash[:error] = @task.errors.full_messages) | (render:edit) is obviously the most complex part of those methods. I'm having trouble understanding it. Why is there a bitwise or? And it's duplicated, except or what to render.

Let's pull this apart. First, turn the ternary operator into an if/else.

if @task.save
  redirect_to root_url
else
  (flash[:error] = @task.errors.full_messages) | (render :edit)
end

I don't think that | is actually doing anything. It's just a way to cram two statements into one.

if @task.save
  redirect_to root_url
else
  flash[:error] = @task.errors.full_messages
  render :edit
end

That is much easier to understand, and it reduces the ABC a bit.

Next is to put the find code into their own private methods. Just a simple extract method.

# Note I left it at just finding the associated project.
# I left the .tasks.new off because that's very specific.
private def current_project
  current_user.projects.find(params[:project_id])
end

private def current_task
  current_user.tasks.find(params[:id])
end

def create
  @task = current_project.tasks.new
  @task.title = task_params[:title]

  if @task.save
    redirect_to root_url
  else
    flash[:error] = @task.errors.full_messages
    render :edit
  end
end

def update
  @task = current_task
  @task.title = task_params[:title]
  @task.deadline = task_params[:deadline]

  if @task.save
    redirect_to root_url
  else
    flash[:error] = @task.errors.full_messages
    render :edit
  end
end

And that will do it. You could take this a step further and extract the save logic, passing in where to render and any other details that might change.

# Note the use of defaults.
private def save_task(render:, redirect_to: root_url)
  if @task.save
    redirect_to(redirect_to)
  else
    flash[:error] = @task.errors.full_messages
    render(render)
  end
end

def create
  @task = current_project.tasks.new
  @task.title = task_params[:title]

  save_task(render: :new)
end

def update
  @task = current_task
  @task.title = task_params[:title]
  @task.deadline = task_params[:deadline]

  save_task(render: :edit)
end

It reveals some possible issues.

create and update are using different methods of finding the task. Seems fishy.Your tasknew and taskfind hide this difference making the code harder to understand.

And update is setting the deadline, but create is not. That suggests setting the @task attributes from task_params should be extracted into a single method.

---

Note that I avoided putting the assignment into the private methods. Even though this technically reduces ABC, it makes the code harder to understand because the method call has a side effect ; it changes the state of the object. Side effects have to be done with purpose.

For example, one could turn current_task and current_project into memoized accessors with defaults.

private def current_project
  @current_project ||= current_user.projects.find(params[:project_id])
end

Now it will only load the object once.