关联在 3 个桌面导轨中

Question

我必须创建与第二个相关的第三个表。

1st table: Schema
2nd table: Entity 
3rd table: Fields

它们之间的关系是：

Schema(id) ===>  Entity
Entity(id) ===> Fields

我已经创建了表和视图，直到实体，但不知道如何为字段创建表

具有以下值的字段：

"clientId"
"name"
"description"
"mnemonic"
"columnType"
"display"
"fallbackId"
"conceptDisplay"
"businessName"

帮助我为其创建模型和视图以显示与实体相关的所有字段：

我试过这样的事情：

entity.rb => 模型

class Entity < ApplicationRecord
  belongs_to :schema
  has_many :fields, dependent: :destroy
end

field.rb => 模型

class Field < ApplicationRecord
  belongs_to :entity
end

schema.rb => 模型

class Schema < ApplicationRecord
  has_many :entities, dependent: :destroy
   has_many :fields, through: :entities

  validates :name, presence: true, uniqueness: true
  validates :schemaId, presence: true, uniqueness: true
end

现场控制器：

class FieldsController < ApplicationController
  def index
    @field = Schema.find_by(id: params[:id]).fields
  end
end

我必须创建 link_to 以显示该实体的所有字段的实体视图

<div class="content">
  <ul>
  <% @entities.each do |data| %>
    <li>
      <%= data.clientId %>
      <%= link_to data.name, fields_index_path(id: data.id) %>
      <%= data.description %>
      <%= data.mnemonic %>
    </li>

  <% end %>
</ul>
</div>

Answer 1

您需要创建这些迁移：

  def change
    create_table :schemas do |t|
      # here all your necessary fields for schema
      t.timestamps
    end
  end

  def change
    create_table :entities do |t|
      t.references :schema, null: false, foreign_key: true
      # here all your necessary fields for entity
      t.timestamps
    end
  end

def change
  create_table :fields do |t|
    t.references :entity, null: false, foreign_key: true
    # here all your necessary fields for field
    t.timestamps
  end
end

并将所有必要的关联添加到您的模型中

# schema.rb
class Schema < ApplicationRecord
  has_many :entities
  has_many :fields, through: :entities
end

# entiry.rb
class Entity < ApplicationRecord
  belongs_to :schema
  has_many :fields
end

# field.rb
class Field < ApplicationRecord
  belongs_to :entiry
end

通过您控制器中的Entity获取Schema的所有fields

# fields_controller.rb
class FieldsController < ApplicationController
  def index
    @fields = Schema.find_by(id: params[:id]).fields
  end
end

并在视图中呈现指向您的字段的所有链接

# views/fields/index.html.erb
<% @fields.each do |field| %>
  <%= link_to field.name, field_path(field) %>
<% end %>

并为您的routes添加必要的资源

# configs/routes
resources :schemas
resources :fields