如何在laravel中显示多对多关系数据？

Question

大家晚上好。当我想要显示多对多的关系数据时，我遇到了一个问题，即使用livewire显示基于标签的邮件数据。以前我尝试过的laravel可以出现。

现在我想用livewire按标签显示post数据，但仍然不能。

下面是我写的代码。

web.php

Route::get('tag/{tag:slug}',[FrontController::class, 'tag'])->name('tag');

FrontController.php

public function tag(Tag $tag)
    {
        $categories = Category::all();
        $general = General::find(1);
        $locale = App::currentLocale();

        $search = request("search");
       
        $posts = $tag->posts()->where([
            ['status','PUBLISH'],
            ['lang',$locale],
        ])->latest()->paginate(12);

        if ($this->search !== null) {
            $posts = $tag->posts()->where([
                ['title','like', '%' . $search . '%'],
                ['lang',$locale],
                ['status','PUBLISH'],
            ])->latest()->paginate(12);
        }

        // dd($posts);

        $tags = Tag::all();
        $top        = Post::where('status','PUBLISH')->orderBy('views','desc')->limit(5)->get();
        return view ('front.tag',compact('categories','general','locale','posts','tags','top'));
    }

tag.blade.php

@extends('layouts.front')

@section('content')
<main id="main">
    <section class="post-category">
        <div class="container-fluid">
            <div class="row mt-3">
                <div class="col-lg-3 col-md-12 col-sm-12 d-none d-lg-block">
                    <div class="sticky-top" style="top: 90px;">
                        <div class="card mb-3 rounded-3">
                            <div class="card-body">
                                <a href="#" target="_blank" rel="noreferrer">
                                    <img src="{{ asset('front/img/ads.png') }}" alt="..." height="300" width="279" class="card-img-top" />
                                </a>
                            </div>
                        </div>
                        <div class="d-flex flex-column mb-3 bg-light shadow bg-body rounded">
                            <div class="card-header bg-primary bg-gradient text-white fw-bold fs-5">
                                {{ __('sentence.category') }}
                            </div>
                            <ul class="list-group list-group-flush">
                                @foreach ($categories as $category)
                                    <li class="list-group-item d-flex justify-content-between align-items-center">
                                        <a href="{{ route('category', $category->slug) }}">{{ $category->name }}</a>
                                    </li>
                                @endforeach
                            </ul>
                        </div>
                        <div class="d-flex flex-column bg-light bg-body shadow-lg rounded-3">
                            <div class="card-header bg-primary bg-gradient text-white fw-bold fs-5">
                                Tags
                            </div>
                            <div class="p-3 overflow-auto" style="max-height: 42vh">
                                <div class="nav tag-cloud">
                                    @foreach ($tags as $tag)
                                        <a href="{{ route('tag', $tag->slug) }}">{{ $tag->name }}</a>
                                    @endforeach   
                                </div>
                            </div>
                        </div>
                    </div>
                </div>
    
                <livewire:tag-index>
                
                <div class="col-lg-3 col-md-12 col-sm-12">
                    <div class="sticky-top" style="top: 90px;">
                        <div class="card rounded-3 shadow-lg mb-3">
                            <div class="card-body">
                                <img src="{{ asset('front/img/ads1.png') }}" height="117" width="279" class="card-img-top" alt="...">
                            </div>
                        </div>
                        <div class="bg-light shadow bg-body rounded-3 mb-3">
                            <div class="card-header bg-primary bg-gradient text-white fw-bold fs-5">
                                {{ __('sentence.top_article') }}
                            </div>
                            <ul class="list-group list-group-flush mb-2">
                                @foreach ($top as $top)
                                <li class="list-group-item">
                                    <a href="{{ route('blogShow', $top->slug) }}">{{ $top->title }}</a>
                                    <div class="d-flex justify-content-between mt-3">
                                        <small class="text-muted">{{ Carbon\Carbon::parse($top->created_at)->format("d F, Y") }}</small>
                                        <small class="text-muted">{{ $top->views }} views </small>
                                    </div>
                                </li>
                                @endforeach
                            </ul>
                        </div>
                        <div class="d-flex flex-column mb-3 bg-light shadow bg-body rounded d-lg-none d-xl-none">
                            <div class="card-header bg-primary bg-gradient text-white fw-bold fs-5">
                                {{ __('sentence.category') }}
                            </div>          
                            <ul class="list-group list-group-flush">
                                @foreach ($categories as $category)
                                    <li class="list-group-item d-flex justify-content-between align-items-center">
                                        <a href="{{ route('category', $category->slug) }}">{{ $category->name }}</a>
                                    </li>
                                @endforeach
                            </ul>
                        </div>
                        <div class="d-flex flex-column bg-light bg-body shadow-lg rounded-3 d-lg-none d-xl-none">
                            <div class="card-header bg-primary bg-gradient text-white fw-bold fs-5">
                                {{ __('sentence.tag') }}
                            </div>
                            <div class="p-3 overflow-auto" style="max-height: 42vh">
                                <div class="nav tag-cloud">
                                    @foreach ($tags as $tag)
                                        <a href="{{ route('tag', $tag->slug) }}">{{ $tag->name }}</a>
                                    @endforeach   
                                </div>
                            </div>
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </section>
</main>
@endsection

@push('scripts')
@livewireScripts
<script type="text/javascript">
    window.onscroll = function (ev) {
        if ((window.innerHeight + window.scrollY) >= document.body.offsetHeight) {
            window.livewire.emit('tag-index');
        }
    };

</script>

<script>
    document.getElementById('load-more').onclick = function() {
        window.livewire.emit('tag-index');
    };
</script>
@endpush

livewire\TagIndex.php

<?php

namespace App\Http\Livewire;

use Livewire\Component;
use App\Models\{Tag, Post};
use Illuminate\Support\Facades\App;

class TagIndex extends Component
{
    public $limitPerPage = 10;

    public $search;

    protected $listeners = [
        'tag-index' => 'TagIndex'
    ];

    protected $updatesQueryString = [
        ['search' => ['except' => '']],
    ];
   
    public function TagIndex()
    {
        $this->limitPerPage = $this->limitPerPage + 6;
    }

    public function render(Tag $tag)
    {
        $locale = App::currentLocale();

        $posts = $tag->posts()->where([
            ['status','PUBLISH'],
            ['lang',$locale],
        ])->latest()->paginate($this->limitPerPage);

        if ($this->search !== null) {
            $posts = $tag->posts()->where([
                ['title','like', '%' . $this->search . '%'],
                ['status','PUBLISH'],
                ['lang',$locale],
            ])->latest()->paginate($this->limitPerPage);
        }
        
        $this->emit('postStore');


        return view('livewire.tag-index', ['posts' => $posts]);
    }
}

livewire\tag-index.blade.php

<div class="col-lg-6 col-md-12 col-sm-12">
    <div id="section-title" class="section-title p-1 pt-3">
        <h2 class="text-center fw-bold">{{ trans('sentence.recent_posts')}}</h2>
    </div>
    <div class="form-group has-search mb-3">
        <span class="bi bi-search form-control-feedback"></span>
        <input type="text" wire:model="search" class="form-control" placeholder="{{ __('sentence.search_form') }}">
    </div>
    @foreach ($posts as $data)
    <div class="card bg-light shadow bg-body rounded-3 mb-2">
        <div class="card-header bg-primary text-white d-flex justify-content-between">
            <small>by {{$data->admin->name}}</small>
            <small>{{ Carbon\Carbon::parse($data->created_at)->format("d F, Y") }}</small>
        </div>
        <div class="card-body">
            <h2 class="card-title">
                <a href="{{ route('blogShow', $data->slug) }}">{{ $data->title }}</a>
            </h2>
            <div class="card-footer bg-body d-flex justify-content-between align-items-center pb-0 px-0">
                <div class="d-flex my-1">
                    @foreach ($data->tags as $tag)
                    <a href="{{ route('tag', $tag->slug) }}" class="badge {{ $tag->bg }} me-1 shadow-sm text-white">{{ $tag->name }}</a>
                    @endforeach
                </div>
            </div>
        </div>
    </div>
    @endforeach
    @if ($posts->count() == 0)
    <div class="alert alert-danger" role="alert">
        Data not found!
    </div>
    @endif
    @if($posts->count() >= 10)
    <div class="text-center d-md-none d-lg-none d-xl-none">
        <button id="load-more" class="btn btn-primary my-3">
        Load More
        </button>
    </div>
    @endif
</div>

用livewire显示多对多关系数据的正确方式或代码是什么？在本例中，我希望按标签显示post数据。谢谢

Answer 1

在你的问题中有很多额外的stuff，所以我为你整理了一个简化的例子。您需要完成剩余的工作才能将其应用到您的项目中。

我不知道你如何显示你的tag标签或其他东西，所以我选择了checkboxes，因为它似乎是最明智的。这些标签可以设置为隐藏，以便更接近于上的tag标签，但同样，我将把bike shedding留给您。

我创建了一个名为Tags的Livewire component和一个关联的blade视图。

tags.blade.php

<div>
    {{-- loop over each of the tags --}}
    @foreach ($this->tags as $tag)
        {{-- wire:key is important here as Livewire requires it for effective DOM diffing! --}}
        <div wire:key="tag-{{ $tag->id }}" class="block px-4 py-2">
            {{-- 
                this is where we bind the checkboxes
                to a property on the Livewire component
            --}}
            <input wire:model="selectedTags" type="checkbox" id="tag-{{ $tag->id }}" name="{{ $tag->title }}" value="{{ $tag->id }}">
            <label for="{{ $tag->title }}">{{ $tag->title }}</label>
        </div>
    @endforeach

    {{-- loop over each of the posts --}}
    @foreach ($this->posts as $post)
        {{-- again, don't overlook wire:key! --}}
        <div wire:key="post-{{ $post->id }}" class="block px-4 py-2">
            <h4 class="text-sm">{{ $post->title }}</h4>
        </div>
    @endforeach
</div>

上面的大部分内容应该是不言而喻的，唯一不能说明的就是wire:model="selectedTags"。在Tags组件上定义了一个名为selectedTags的公共属性(稍后您将看到)，它允许我们在选中其中一个复选框时管理该数组中的元素。因此，例如，当某人使用id of 12选中tag复选框时，selectedTags数组会添加一个带有value of 12的元素。

Tags.php

class Tags extends Component
{
    // array of selected tags (checked checkboxes)
    public $selectedTags = [];

    // get just the id and title of each tag
    public function getTagsProperty()
    {
        return Tag::select('id', 'title')->get();
    }

    public function getPostsProperty()
    {
        $tags = array_filter($this->selectedTags);

        // if no tags are selected, return all posts
        // you might decide to return nothing, up to you
        if (!$tags) {
            return Post::all();
        }

        // if there are some selected tags
        // query the database for posts with the selectedTags
        // this is an `OR` operation on tags
        // if you want `AND` you'll need to change it
        return Post::whereHas('tags', function ($query) use ($tags) {
            $query->whereIn('tags.id', $tags);
        })->get();
    }

    public function render()
    {
        return view('livewire.tags');
    }
}

同样，上面的内容应该是不言而喻的，因为没有任何异常发生。

getPostsProperty()和getTagsProperty()函数定义了computed properties，这是可选的，如果您愿意，您可以只使用普通属性。但是，如果您在组件视图中多次引用$tags和$posts，则计算属性的性能更高，因为它不会每次都调用后端组件。

Answer 2

已解决的

感谢@Peppermintology帮助我解决了两个问题，现在这个问题已经用下面的代码解决了。

FrontController.php

 public function tag(Tag $tag)
    {
        $categories = Category::all();
        $general = General::find(1);
        $locale = App::currentLocale();
        $tag_id = $tag->id;

        $search = request("search");
       
        $posts = $tag->posts()->where([
            ['status','PUBLISH'],
            ['lang',$locale],
        ])->latest()->paginate(12);

        if ($this->search !== null) {
            $posts = $tag->posts()->where([
                ['title','like', '%' . $search . '%'],
                ['lang',$locale],
                ['status','PUBLISH'],
            ])->latest()->paginate(12);
        }

        $tags = Tag::all();
        $top        = Post::where('status','PUBLISH')->orderBy('views','desc')->limit(5)->get();
        return view ('front.tag',compact('categories','general','locale','posts','tags','tag_id','top'));
    }

livewire\TagIndex.php

<?php

namespace App\Http\Livewire;

use Livewire\Component;
use App\Models\{Tag, Post};
use Illuminate\Support\Facades\App;

class TagIndex extends Component
{
    public $limitPerPage = 10;

    public $search, $tagId;

    protected $listeners = [
        'tag-index' => 'TagIndex'
    ];


    protected $updatesQueryString = [
        ['search' => ['except' => '']],
    ];
   
    public function TagIndex()
    {
        $this->limitPerPage = $this->limitPerPage + 6;
    }

    public function render()
    {
        $locale = App::currentLocale();
        $tag_id = $this->tagId;

        $tag = Tag::find($tag_id);  

        $posts = $tag->posts()->where([
            ['status','PUBLISH'],
            ['lang',$locale],
        ])->latest()->paginate($this->limitPerPage);

        if ($this->search !== null) {
            $posts = $tag->posts()->where([
                ['title','like', '%' . $this->search . '%'],
                ['status','PUBLISH'],
                ['lang',$locale],
            ])->latest()->paginate($this->limitPerPage);
        }
        
        $this->emit('postStore');

        // dd($posts);

        return view('livewire.tag-index', ['posts' => $posts, 'tag' => $tag]);
    }
}