Rails：從表單發佈到M：M表

Question

在小組索引頁面上，我將顯示小組討論列表和表單以創建新討論。

class Group < ActiveRecord::Base 
    has_many :discussions 
end 

class Discussion < ActiveRecord::Base 
    belongs_to :user 
    belongs_to :group 
end 

控制器：

class DiscussionsController < ApplicationController 
    def index 
    @group = Group.find(params[:group_id]) 
    @discussion = current_user.discussions.build({group_id: @group.id}) if logged_in? 
    @discussions = @group.discussions 
    end 

    def create 
    @discussion = current_user.discussions.build(discussion_params) 
    if @discussion.save 
     flash[:success] = "Discussion started." 
     redirect_to root_url 
    end 
    end 

    private 

    def discussion_params 
     params.require(:discussion).permit(:title, :content) 
    end 
end 

我的形式如下。

<%= form_for([@group, @discussion]) do |f| %> 
    <%= render 'shared/error_messages', object: f.object %> 
    <div class="field"> 
    <%= f.text_field :title, placeholder: "Title" %> 
    </div> 
    <div class="field"> 
    <%= f.text_area :content, placeholder: "Start a discussion..." %> 
    </div> 
    <%= f.submit "Post", class: "btn btn-primary" %> 
<% end %> 

但是，當表單提交時記錄的行沒有group_id時，這可以正常工作。我懷疑問題在於我在創建操作中構建討論對象的方式，但我不確定如何以不同方式進行操作。

Started POST "/groups/635601/discussions" for 127.0.0.1 at 2015-06-22 15:16:07 +1000 
    ActiveRecord::SchemaMigration Load (0.3ms) SELECT "schema_migrations".* FROM "schema_migrations" 
Processing by DiscussionsController#create as HTML 
    Parameters: {"utf8"=>"✓", "authenticity_token"=>"tJWJQKb6NcS1EAaeeLramzQp82xf4hLrXt+UTzKQo8+i1ePoNLYr8jXYSgBLpSxNvoPOAfNxnim1Ln6fKJ0uiw==", "discussion"=>{"title"=>"Test1", "content"=>"Test2"}, "commit"=>"Post", "group_id"=>"635601"} 
    User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 406]] 
    (0.1ms) begin transaction 
    SQL (0.4ms) INSERT INTO "discussions" ("title", "content", "user_id", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?) [["title", "Test1"], ["content", "Test2"], ["user_id", 406], ["created_at", "2015-06-22 05:16:07.883843"], ["updated_at", "2015-06-22 05:16:07.883843"]] 
    (13.9ms) commit transaction 
Redirected to http://localhost:3000/ 
Completed 302 Found in 81ms (ActiveRecord: 15.5ms) 

我可以在params集合中看到group_id在那裏但在散列之外。

Answer 1

正如我所說，你需要調整你的create這樣的行動，以節省group_id。

def create 
@group = Group.find(params[:group_id]) 
@discussion = current_user.discussions.build(discussion_params) 
@discussion.group_id = @group.id 
if @discussion.save 
    flash[:success] = "Discussion started." 
    redirect_to root_url 
end 
end 

OR

您可以添加hidden_field在form_for保存group_id這樣

<%= f.hidden_field :group_id, :value => @group.id %> 

在這種情況下，您create行動會是這樣

def create 
@group = Group.find(params[:group_id]) 
@discussion = current_user.discussions.build(discussion_params) 
if @discussion.save 
    flash[:success] = "Discussion started." 
    redirect_to root_url 
end 
end 

而且你需要添加group_id您discussion_params以及

def discussion_params 
    params.require(:discussion).permit(:title, :content, :group_id) 
end 

而且，是的，它是完全的Rails做的方式。