Laravel 5.多对多的关系。建立查询

Question

表：

categories 
--id 

materials 
--id 

category_material 
--id 
--category_id 
--material_id 

型号：

class Material extends Model { 
    public function categories(){ 
     return $this->belongsToMany('App\Category'); 
    } 
} 

class Category extends Model { 
    public function materials(){ 
     return $this->belongsToMany('App\Material'); 
    } 
} 

我需要从 “CATEGORY_ID = 1”

所有材料尝试：

$category_id = '1'; 
$materials = Material::with('categories')->where('category_id', $category_id)->get(); 

未知列“材料.category_id'

$category_id = '1'; 
$materials = Material::with(['categories',function($query) use ($category_id){ 
    $query->where('category_id', $category_id); 
}])->get(); 

ErrorException在Builder.php行792： 爆炸（）预计参数2为字符串，对象给出

请帮助我。

Answer 1

阵列传递给with应该在relation_name => closure格式

$category_id = '1'; 
$materials = Material::whereHas('categories', function($query) use ($category_id){ 
    $query->where('category_id', $category_id); 
})->get();