Laravel:有没有可能直接从图书集合中获取所有作者而不进行循环?

Question

我一直在努力把所有作者从藏书中找出来。

$books = Books::all();
foreach($books as $book){ $book->author ... 

这段代码将工作，但我想获得所有作者不使用循环

$allAuthorsThruBooks = Books::someQueryMaybe();

$allAuthorsThruBooks将显示作者列表。

谢谢!

Answer 1

假设所有模型都在Models目录AppModels

书模型

use AppModelsAuthor;
...    
Class Books extends Model
{
public function author()
{
return $this->belongsTo(Author::class, 'author_id');
}
}

查询

$books = Books::with(['author'])->get();
// with condition
$books = Books::with(['author' => function($query)
$query->where(...);
])->get();

例子结果

[
id: 1,
name: 'Book One',
author: [
id: 1,
name: 'Maddog'
]
],
[...]

Answer 2

方法01

<尝试strong>摘下

$authorList = collect($books)->pluck('author')->unique();
// use ->toArray() if you want to convert into array

---

方法02

创建助手

namespace AppHelpers;

use IlluminateSupportArr;
class ArrHelper
{
public static function onlyValues($array = [], $keys = [])
{
return array_filter(
array_values(
Arr::only($array, $keys)
)
);
}
}

在控制器

$authorList = collect(ArrHelper::onlyValues($books, ['author']));