Ruby on rails Rails：查找或创建关系

如果我为训练创建了一个新的练习，则我的字段

成员id

为空

workout.rb

     belongs_to :member
     has_and_belongs_to_many :exercises

     def add_exercise_with_name(exercise_name)
        self.exercises << Exercise.find_or_create_by(name: exercise_name)
      end

练习_controller.erb

def create
    @workout = current_user.workouts.find(params[:workout_id])
    @exercise = @workout.add_exercise_with_name(exercises_params['name'])
    redirect_to workout_path(@workout)
end

---

我如何才能为练习添加成员？

在您的

训练中尝试此选项

型号：

def add_exercise_with_name(exercise_name, member)
  self.exercises << Exercise.find_or_create_by(name: exercise_name, member: member)
end

---

将id作为额外参数传递给方法

def add_exercise_with_name(exercise_name, member_id)
  self.exercises << Exercise.find_or_create_by(name: exercise_name, member_id: member_id)
end

此外，还可以使用块语法：

  self.exercises << Exercise.find_or_create_by(name: exercise_name) do |exercise|
    exercise.member_id = member_id
  end

---

self.exercises如果遵循关联，则外键将自动填充。
在控制器中，您还可以通过关联使用ActiveRecord请求：

class Member < ActiveRecord::Base
  has_many :workouts
  has_many :exercises, through: :workouts
end


class Workout < ActiveRecord::Base
  belongs_to :member
  has_and_belongs_to_many :exercises
end


class Exercise < ActiveRecord::Base
  belongs_to :member
  has_and_belongs_to_many :workouts
end


class ExercisesController < ActionController::Base
  before_action :get_workout

  def create
    @workout.exercises.where(name: exercises_params['name']).first_or_create
    redirect_to workout_path(@workout)
  end

  private

  def get_workout
    @workout = current_user.workouts.find(params[:workout_id])
  end
end 

类成员
由于指出了警告，这个答案可能更好。因此，如果练习属于成员，我将执行
find\u或\u create\u by（name:exercise\u name）
它将使用名称相同但可能不同的“owner”/member？@orgertot yes的练习。如果将
成员id
包含在
查找或创建人
中，则查询
where
子句将包含两个条件
其中name='foo'和member\u id=1
。这可能是您想要的，也可能不是您想要的，这取决于您想要如何设计您的系统。
self.exercises << Exercise.create_with(member_id: member_id).find_or_create_by(name: exercise_name)

  self.exercises << Exercise.find_or_create_by(name: exercise_name) do |exercise|
    exercise.member_id = member_id
  end

class Member < ActiveRecord::Base
  has_many :workouts
  has_many :exercises, through: :workouts
end


class Workout < ActiveRecord::Base
  belongs_to :member
  has_and_belongs_to_many :exercises
end


class Exercise < ActiveRecord::Base
  belongs_to :member
  has_and_belongs_to_many :workouts
end


class ExercisesController < ActionController::Base
  before_action :get_workout

  def create
    @workout.exercises.where(name: exercises_params['name']).first_or_create
    redirect_to workout_path(@workout)
  end

  private

  def get_workout
    @workout = current_user.workouts.find(params[:workout_id])
  end
end