使用预先加载来获取给定文章中的所有相关文章

Question

I want to get all related articles of particular article based on category.

I have relation between Article and Category

Article.php

public function category(){

    return $this->belongsTo(ArticleCategory::class,'category_id','id');

}

ArticleCategory.php

 public function articles(){

    return $this->hasMany(Article::class,'category_id','id');

}

ArticleController.php

public function singleArticle(Article $article){

    //I want to convert this statement to eager loading statement

    $relatedArticles = $article->category->articles;

    return view('pages/article',compact('article','relatedArticles'));

}

Answer 1

You can also use whereHas() if you want to just get related articles:

$relatedArticles = Article::whereHas('category', function($q) use($article) {
    $q->where('id', $article->category_id);
})
->get();

If you want load everything to one collection:

$relatedArticles = Article::with(['category.articles' => function($q) use($article) {
    $q->where('id', $article->category_id);
}])
->get();

Answer 2

If you wanna have the category model always eager load its articles out of the box, you could add

protected $with = ['articles'];

to the Category.php file.

With that you then could just use $article->category

This also works for the implicit bindings in a function call, so you could eager load category for every article when you write in Article.php

protected $with = ['category'];

Sadly if you wanna eagerload everything with

protected $with = ['category.articles'];

you get an endless loop in this case. Just for info for similar cases in the future, you can do nested eager loading with this.