一、创建模型

创建评论模型

php artisan make:model Comment -m

修改生成的 database/migrations/create_comments_table.php

public function up()
{
    Schema::create('comments', function (Blueprint $table) {
        $table->increments('id');
        $table->unsignedInteger('user_id');
        $table->text('content');
        $table->unsignedInteger('commentable_id');
        $table->string('commentable_type');
        $table->timestamps();
    });
}

执行数据迁移

php artisan migrate

修改 app/Comment.php

protected $table = 'comments';

protected $fillable = ['user_id','content','commentable_id','commentable_type'];

public function commentable()
{
    return $this->morphTo();
}

public function user()
{
    return $this->belongsTo(User::class);
}

修改 app/Answer.php

public function comments()
{
    return $this->morphMany('App\Comment','commentable');
}

修改 app/Question.php

public function comments()
{
    return $this->morphMany('App\Comment','commentable');
}

二、创建控制器

创建评论控制器

php artisan make:controller CommentsController

修改 routes/api.php

Route::post('/comments', 'CommentsController@index');
Route::post('/comment/store', 'CommentsController@store')->middleware('auth:api');

修改 app/Repositories/QuestionRepository.php

public function getQuestionCommentsById($id)
{
    $question = Question::with('comments','comments.user')->where('id',$id)->first();
    return $question->comments;
}

修改 app/Repositories/AnswerRepository.php

public function getAnswerCommentsById($id)
{
    $answer = Answer::with('comments','comments.user')->where('id',$id)->first();
    return $answer->comments;
}

新建 app/Repositories/CommentRepository.php

namespace App\Repositories;

use App\Comment;

class CommentRepository
{
    public function create(array $attributes)
    {
        return Comment::create($attributes);
    }
}

修改生成的控制器：app/Http/Controllers/CommentsController.php

namespace App\Http\Controllers;

use App\Repositories\AnswerRepository;
use App\Repositories\CommentRepository;
use App\Repositories\QuestionRepository;
use Auth;

class CommentsController extends Controller
{
    private $answerRepository;
    private $commentRepository;
    private $questionRepository;

    public function __construct(AnswerRepository $answerRepository, CommentRepository $commentRepository, QuestionRepository $questionRepository)
    {
        $this->answerRepository = $answerRepository;
        $this->commentRepository = $commentRepository;
        $this->questionRepository = $questionRepository;
    }

    public function index()
    {
        if(request('type') == 'question'){
            return $this->questionRepository->getQuestionCommentsById(request('model'));
        }
        return $this->answerRepository->getAnswerCommentsById(request('model'));
    }

    public function store()
    {
        $model = $this->getModelNameFormType(request('type'));
        return $this->commentRepository->create([
            'commentable_id' => request('model'),
            'commentable_type' => $model,
            'user_id' => user('api')->id,
            'content' => request('content'),
        ]);
    }

    private function getModelNameFormType($type)
    {
        return $type === 'question' ? 'App\Question' : 'App\Answer';
    }
}

三、创建视图

修改 resources/views/layouts/app.blade.php

window.Laravel = <?php echo json_encode([
    'csrfToken' => csrf_token(),
]); ?>;
Laravel.apiToken = "{{ Auth::check() ? 'Bearer '.Auth::user()->api_token : ''}}"
@if(Auth::check())
    window.Zhihu = {
        name:"{{Auth::user()->name}}",
        avatar:"{{Auth::user()->avatar}}"
    }
@endif

新建 resources/assets/js/components/comments.vue

注册组件：修改 resources/assets/js/app.js

Vue.component('comments', require('./components/Comments.vue'));

执行 gulp

gulp

修改 resources/views/questions/show.blade.php

访问：http://127.0.0.1:8000/questions/id，id 为问题 ID

点击按钮进行测试