拉勒维尔5.多对多的关系。构建查询

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"category_id = 1“的所有材料

试着：

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

未知列'materials.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第792行:Builder.php()期望参数2是字符串，对象给定

帮帮我求你了。

Answer 1

传递给with的数组应该是relation_name => closure格式的

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