Rails: find_or_create 关系

Question

如果我为锻炼创建新练习，我的字段 member_id 是空的。

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

exercise.erb

has_and_belongs_to_many :workouts
belongs_to :member

exercise_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

如何为练习添加成员？

Answer 1

在您的 Workout 型号上试试这个：

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

然后在你的控制器中传入成员：

member = Member.find_by whatever_column: 'value'
@exercise = @workout.add_exercise_with_name(exercises_params['name'], member)

Answer 2

将 id 作为额外参数传递给该方法。

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

这有副作用。现在 find_or_create 调用将在查找练习时考虑 member_id。如果这是不可取的，请使用 create_with(member_id: member_id).

self.exercises << Exercise.create_with(member_id: member_id).find_or_create_by(name: exercise_name)

此外，您可以使用块语法：

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

Answer 3

如果您遵循关联，则外键会自动填充。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

Rails: find_or_create 关系

Rails: find_or_create relation

ruby

ruby-on-rails

relational-database

ruby-on-rails-4