构建 Laravel 多级评论系统：父子评论关系管理与展示

Schema::create('article_comments', function (Blueprint $table) {
   $table->bigIncrements('id');
   $table->unsignedBigInteger('article_id');
   $table->foreign('article_id')
         ->references('id')->on('articles')->onDelete('cascade'); // 关联文章
   $table->string('name');
   $table->string('email');
   $table->text('text');
   $table->string('date'); // 评论日期

   $table->unsignedBigInteger('comment_id')->nullable(); // 自引用外键，用于回复
   $table->foreign('comment_id')
         ->references('id')->on('article_comments')->onDelete('set null'); // 父评论删除时，子评论的 comment_id 设为 null

   $table->timestamps();
});

// app/Models/ArticleComment.php
<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class ArticleComment extends Model
{
    use HasFactory;

    protected $fillable = [
        'article_id', 'name', 'email', 'text', 'date', 'comment_id'
    ];

    /**
     * 获取当前评论的所有直接回复。
     */
    public function answers()
    {
        return $this->hasMany(ArticleComment::class, 'comment_id', 'id');
    }

    /**
     * 获取当前回复所属的父评论。
     */
    public function parentComment()
    {
        return $this->belongsTo(ArticleComment::class, 'comment_id', 'id');
    }

    /**
     * 获取评论所属的文章。
     */
    public function article()
    {
        return $this->belongsTo(Article::class);
    }
}

// app/Models/Article.php
<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Article extends Model
{
    use HasFactory;

    protected $fillable = ['title', 'content']; // 示例字段

    /**
     * 获取文章的所有评论。
     */
    public function comments()
    {
        return $this->hasMany(ArticleComment::class, 'article_id', 'id');
    }
}

use App\Models\Article;

$articleId = 1; // 假设文章ID为1

$articleWithCommentsAndReplies = Article::where('id', $articleId)
    ->with(['comments' => function($query) {
        $query->whereNull('comment_id') // 仅获取顶级评论
              ->with('answers');       // 预加载顶级评论的直接回复
    }])
    ->first(); // 使用 first() 获取单个文章模型

// 如果需要获取所有文章及其评论，可以使用 get()
// $articles = Article::with(['comments' => function($q) { ... }])->get();

// 示例输出结构 (toArray() 转换后)
/*
[
  {
    "id": 1,
    "title": "文章标题 1",
    "content": "文章内容...",
    "comments": [
      {
        "id": 1,
        "article_id": 1,
        "name": "用户A",
        "text": "这是一条顶级评论。",
        "comment_id": null, // 顶级评论
        "answers": [ // 顶级评论的回复
          {
            "id": 5,
            "article_id": 1,
            "name": "用户B",
            "text": "回复用户A的评论1。",
            "comment_id": 1
          },
          {
            "id": 6,
            "article_id": 1,
            "name": "用户C",
            "text": "回复用户A的评论2。",
            "comment_id": 1
          }
        ]
      },
      {
        "id": 2,
        "article_id": 1,
        "name": "用户D",
        "text": "这是另一条顶级评论。",
        "comment_id": null,
        "answers": [] // 没有回复
      }
    ]
  }
]
*/

use App\Models\ArticleComment;

$parentCommentId = 1; // 假设父评论ID为1

$repliesToComment = ArticleComment::where('comment_id', $parentCommentId)
    ->get();

// 示例输出：所有 comment_id 为 1 的评论

use App\Models\ArticleComment;

$commentId = 1; // 假设顶级评论ID为1

$commentWithItsReplies = ArticleComment::where('id', $commentId)
    ->with('answers')
    ->first();

// 示例输出：ID为1的评论及其answers

<!-- resources/views/articles/show.blade.php -->

<div class="comment-list">
    @if($articleWithCommentsAndReplies && $articleWithCommentsAndReplies->comments->isNotEmpty())
        @foreach($articleWithCommentsAndReplies->comments as $comment)
            {{-- 顶级评论 --}}
            <div class="comment-list__item">
                <div class="item-card">
                    <div class="item-card__header">
                        <div class="item-card__title">
                            <div class="label">
                                {!! $comment->name !!}
                            </div>
                            <div class="data">
                                {!! date('d F Y', strtotime($comment->date)) !!}
                            </div>
                        </div>
                    </div>
                    <div class="item-card__content">
                        {!! $comment->text !!}
                    </div>
                </div>

                {{-- 如果存在回复，则显示回复列表 --}}
                @if($comment->answers->isNotEmpty())
                    <div class="comment-sub-list">
                        @foreach($comment->answers as $reply)
                            <div class="comment-sub-list__item">
                                <div class="item-card">
                                    <div class="item-card__header">
                                        <div class="item-card__title">
                                            <div class="label">
                                                {!! $reply->name !!}
                                            </div>
                                            <div class="data">
                                                {!! date('d F Y', strtotime($reply->date)) !!}
                                            </div>
                                        </div>
                                    </div>
                                    <div class="item-card__content">
                                        {!! $reply->text !!}
                                    </div>
                                </div>
                            </div>
                        @endforeach
                    </div>
                @endif
            </div>
        @endforeach
    @else
        <p>暂无评论。</p>
    @endif
</div>