rails 巢狀留言
功能製作教學
前情提要：
本篇將教學巢狀留言怎麼設定
安裝插件
巢狀留言軟刪除
如果今天已經幫留言設定好了軟刪除，但是想要把被刪除的留言顯示出來，並且顯示的是特定文字(留言已被使用者刪除)，這樣要怎麼做呢？
看過官方文件後，只要這樣輸入，就可以把不管有沒有被刪除過的東西都抓出來
> YourModel.readonly.with_deleted
> 這樣可以把指定model的物件全部抓出來，不管有沒有被軟刪除過
讓我們來看看實際樣子：
# controllers/houses_controller.rb
class HousesController < ApplicationController
before_action :find_house, only: [:show, :like, :dislike]
def show
@comment = @house.comments.new
# 注意這段
@comments = @house.comments.readonly.with_deleted.where("parent_id IS NULL OR parent_id = 0")
end
private
def find_house
@house = House.find(params[:id])
end
end
可以看到 @comments 這邊，他把留言全部抓出來後，再補上後面那一段where，那一段的意思是，找到 root_houses，因為我們做的是巢狀留言，所以這邊先把沒有子留言的抓出來
接著我們把留言顯示出來
<!-- views/houses/show.html.erb -->
<section class="mt-36 mx-36">
<div class="mb-6 bg-white rounded-lg shadow">
<%# 渲染房子上方區塊 %>
<%= render "card", house: @house %>
<div class="w-full p-4 text-gray-600 focus-within:text-gray-400">
<%# 下面這邊是渲染留言表單出來，順便會把兩個實體變數傳過去，一個是房子實體變數傳過去變區域變數，一個是把nil當作parent區域變數傳過去 <%>
<%= render partial: 'comments/form', locals: { house: @house, parent: nil, url: comments_path(@house) } %>
</div>
<div class="w-full p-10 mb-8 border-gray-100 border-y">
<%= render @comments %>
</div>
<br>
</div>
</section>
可以看到這一行：
<div class="w-full p-10 mb-8 border-gray-100 border-y">
<%= render @comments %>
</div>
這一段可以渲染出這個畫面：
<!-- views/comments/_comments -->
<div class="my-2 text-sm text-gray-600">
<span><%= comment.deleted_at ? "這則留言被該用戶刪除" : simple_format(comment.content) %></span>
</div>
這邊可以看到，我們先判斷留言的deleted_at是否有資料，如果今天有資料，就代表這則留言已經被刪除，如果沒有，就代表該留言還存在，因此我們寫一個判斷式，就是上面呈現的那樣
子留言的軟刪除
我們想要把子留言留在父留言的下方，因此我們這樣做：
<!-- views/comments/_comments -->
<div class="my-2 text-sm text-gray-600">
<span><%= comment.deleted_at ? "這則留言被該用戶刪除" : simple_format(comment.content) %></span>
</div>
<div class="mt-10">
<%= render comment.comments.readonly.with_deleted %>
</div>
這樣我們就可以把父留言、子留言已經被刪除的留言都顯示出來
實際例子
我們實際把東西印出來看看，我們先把正常的樣子印出來，一間房屋會有很多留言
> h = House.first
> h.comments
>
> ------
> [#<Comment:0x00000001137940a0
> id: 71,
> content: "fdsfdsf",
> user_id: 1,
> house_id: 9,
> created_at: Tue, 02 May 2023 15:29:16.264570000 CST +08:00,
> updated_at: Tue, 02 May 2023 15:29:16.264570000 CST +08:00,
> parent_id: 68,
> deleted_at: nil>,
> #<Comment:0x000000011378ff00
> id: 66,
> content: "讚讚好棒",
> user_id: 2,
> house_id: 9,
> created_at: Thu, 27 Apr 2023 17:34:24.227720000 CST +08:00,
> updated_at: Thu, 27 Apr 2023 17:34:24.227720000 CST +08:00,
> parent_id: nil,
> deleted_at: nil>,
> #<Comment:0x000000011378fd98
> id: 67,
> content: "我好爛",
> user_id: 2,
> house_id: 9,
> created_at: Thu, 27 Apr 2023 17:34:29.893655000 CST +08:00,
> updated_at: Thu, 27 Apr 2023 17:34:29.893655000 CST +08:00,
> parent_id: 66,
> deleted_at: nil>,
> #<Comment:0x000000011378fc30
> id: 68,
> content: "我\n好\n棒",
> user_id: 2,
> house_id: 9,
> created_at: Fri, 28 Apr 2023 16:47:42.343017000 CST +08:00,
> updated_at: Fri, 28 Apr 2023 16:47:42.343017000 CST +08:00,
> parent_id: nil,
> deleted_at: nil>]
不過上面那樣輸入指令，只會把沒被軟刪除的留言列出來，我們來看看用 readonly.with_deleted 這個指令：
> h = House.first
> h.comments.readonly.with_deleted
------
> [#<Comment:0x0000000114d670f8
> id: 71,
> content: "fdsfdsf",
> user_id: 1,
> house_id: 9,
> created_at: Tue, 02 May 2023 15:29:16.264570000 CST +08:00,
> updated_at: Tue, 02 May 2023 15:29:16.264570000 CST +08:00,
> parent_id: 68,
> deleted_at: nil>,
> #<Comment:0x0000000114d66f90
> id: 65,
> content: "讚讚讚",
> user_id: 2,
> house_id: 9,
> created_at: Thu, 27 Apr 2023 15:01:26.975122000 CST +08:00,
> updated_at: Thu, 27 Apr 2023 15:03:00.691882000 CST +08:00,
> parent_id: 64,
> deleted_at: Thu, 27 Apr 2023 15:03:00.691850000 CST +08:00>,
> #<Comment:0x0000000114d66e28
> id: 64,
> content: "哇哇哇",
> user_id: 2,
> house_id: 9,
> created_at: Thu, 27 Apr 2023 15:01:21.818236000 CST +08:00,
> updated_at: Thu, 27 Apr 2023 15:03:03.701301000 CST +08:00,
> parent_id: nil,
> deleted_at: Thu, 27 Apr 2023 15:03:03.701293000 CST +08:00>,
> #<Comment:0x0000000114d66cc0
> id: 66,
> content: "讚讚好棒",
> user_id: 2,
> house_id: 9,
> created_at: Thu, 27 Apr 2023 17:34:24.227720000 CST +08:00,
> updated_at: Thu, 27 Apr 2023 17:34:24.227720000 CST +08:00,
> parent_id: nil,
> deleted_at: nil>,
> #<Comment:0x0000000114d66b58
> id: 67,
> content: "我好爛",
> user_id: 2,
> house_id: 9,
> created_at: Thu, 27 Apr 2023 17:34:29.893655000 CST +08:00,
> updated_at: Thu, 27 Apr 2023 17:34:29.893655000 CST +08:00,
> parent_id: 66,
> deleted_at: nil>,
> #<Comment:0x0000000114d669f0
> id: 68,
> content: "我\n好\n棒",
> user_id: 2,
> house_id: 9,
> created_at: Fri, 28 Apr 2023 16:47:42.343017000 CST +08:00,
> updated_at: Fri, 28 Apr 2023 16:47:42.343017000 CST +08:00,
> parent_id: nil,
> deleted_at: nil>,
> #<Comment:0x0000000114d66888
> id: 70,
> content: "你好棒",
> user_id: 1,
> house_id: 9,
> created_at: Tue, 02 May 2023 15:27:43.352346000 CST +08:00,
> updated_at: Tue, 02 May 2023 15:28:23.829312000 CST +08:00,
> parent_id: 68,
> deleted_at: Tue, 02 May 2023 15:28:23.829200000 CST +08:00>]
上面輸入後，可以看到我們把所有留言都抓到了， deleted_at 有數據的留言，就是代表該留言在該時間點被刪掉。