mysql - SQLSTATE[42S22] : Column not found: 1054 Unknown column 'categories.sub_category_id' in 'where clause' -- Laravel 5

Question

我有两个表类别和子类别，我想显示该类别及其连接的子类别。为此，我创建了一个查询。当我尝试使用一对多关系从类别表中获取类别名称时，它显示错误。

表格结构如下
类别；身份证、姓名
子类别:id、category_id、subname

// Category.php model   
class Category extends Model
{
    protected $primaryKey = 'id';
    protected $table = "categories";

    public function subcategories()
    {
        return $this->hasMany('App\SubCategory');
    } 
}

// Subcategory.php model       
class SubCategory extends Model
{
    protected $primaryKey = 'id';
   protected $table = "subcategories";

     public function category()
     {
         return $this->hasMany('App\Category');
     } 
}

// Category Controller
public function show()
{     
    $categories=  Category::all();
    $subcategories=Subcategory::all();
    return view('show',compact('categories','subcategories'));
}

// show.blade.php
@foreach($subcategories as  $subcategory)
    {{ $subcategory->subname }}
    {{ $subcategory->category_id }}
    {{ $subcategory->category->name }}
@endforeach

这一行给我错误 {{ $subcategory->category->name }}。

Answer 1

i need to change hasmany to belongsTo

你是right因为子类别只有一个类别，你需要使用 belongsTo 关系

class SubCategory extends Model
{
    protected $primaryKey = 'id';
    protected $table = "subcategories";

    public function category()
    {
        return $this->belongsTo('App\Category');
    } 
}