如何在ruby中为用户和任务模型之间的has_many，belong_to关联创建迁移脚本

Question

I have two model User and Task. Task would have one owner and other as workers.

class Task < ApplicationRecord
    belongs_to :user
    has_many :user
end



class User < ApplicationRecord 
    has_many :user
end

how write its migration script. i dont know much about ruby so please correct if i am wrong.

Answer 1

You have create a separate table for has_many through association to join multiple users to multiple tasks

class User < ApplicationRecord

    # association to define tasked owned by users
    has_many :tasks, :class_name => 'Tasks', :foreign_key => 'owner_id'

    # second association to related worker tasks for each user
    has_many :tasks_workers
    has_many :workerfortasks, through: :tasks_workers,  :source => :tasks
end

class Task < ApplicationRecord

    belongs_to :owner , :class_name => 'User', :foreign_key => 'owner_id'       
    has_many :users_tasks
    has_many :workers, through: :tasks_workers,  :source => :users
end

class TasksWorkers < ApplicationRecord
    belongs_to :user
    belongs_to :task
end

Then, you load the tasks for each user using eager_load or includes joins like following or vice versa

  user = User.find(user_id).eager_loads(:tasks)

To generate the migration scripts, run the following terminal commands from the root of the project folder. Note - You can add additional properties to the tables according to your usecase.

#Generate task migration script
$ rails g model tasks owner_id:integer name:string

#Generate user migration script
$ rails g model users name:string email:string

#Generate tasksworkers migration script
$ rails g model tasks_workers task_id:integer user_id:integer

The above three rails commands will generate three migration script in your project_root/db folder.

You can also refer to the same question posted here .