Question

我是laravel 5.2的新手。

有没有人会帮我一个例子来定义类别之间的模型关系 - 子类别 - 产品以及如何通过相关ID获取子类别下的产品？

    // Category  model
public function subcategories(){ return $this->hasMany('App\Subcategory', 'category_id'); }    
public function products() {return $this->hasMany('App\Product', 'subcategory_id');}

// Subcategory model 
public function categories() {return $this->belongsTo('Category');}
public function products() {return $this->hasManyThrough('App\Product'
,'App\Category','subcategory_id','category_id','id');}

// Product model
public function categories() {   return $this->belongsTo('App\Category');}
public function subcategories() {return $this->belongsTo('App\Subcategory');}

// my controller
// class to fetch subcategories under category
public function show_subcategory($name){  
$categories=Category::whereName($name)->get(); 
return view('project.show_subcategory')->with('categories',$categories); 
} 

// class to fetch product under subcategories    
public function show_product($id){ 
$subcategories = Subcategory::whereId($id)->get();
return view('project.show_product')->with('subcategories',$subcategories);}

 //  views - show_subcategory.blade.php
@foreach( $categories as $category)
@foreach( $category->subcategories as $subcategory )    
{{$subcategory->name}}
@endforeach
@endforeach 

//  views - show_product.blade.php
@foreach( $subcategories as $subcategory) 
@foreach( $subcategory->products as $product ) 
{{$product->title}}
@endforeach 
@endforeach

Route::get('/show_subcategory/{name}','Project\MainController@show_subcategory');
Route::get('/show_product/{id}','Project\MainController@show_product');

// migrations - create_subcategories_table.php
$table->engine = 'InnoDB';
$table->increments('id');
$table->string('name');
$table->string('image');
$table->integer('category_id')->unsigned();
$table->foreign('category_id')->references('id')->on('categories')->onDelete('cascade'); 
$table->timestamps();

// migrations - create_products_table.php
$table->engine = 'InnoDB';            
$table->increments('id');
$table->integer('subcategory_id')->unsigned();
$table->foreign('subcategory_id')->references('id')->on('subcategories')->onDelete('cascade'); 
$table->string('title');
$table->text('description');
$table->integer('price');
$table->boolean('availability')->default(1);
$table->string('image');
$table->timestamps();

注意：类show_subcategory运行良好，我可以在类别
下显示子类别
但是show_product类不工作，我无法显示产品   子类别..视图不显示任何错误，不显示   产品

我不知道模型关系或控制器类或视图中的错误在哪里

Answer 1

你的错误：

您试图获取产品INTO子类别表：/，您的子类别表没有产品信息。
您尝试过滤子类别WHERE id = $ id，这是获取子类别信息而非产品信息。尝试做：

url：

/show_product/1

刀片：

@foreach( $subcategories as $subcategory) 

{{$subcategory->name}}

@endforeach

它将起作用，并将显示子类别ID为1的子类别名称。

使用SUBCATEGORY获取产品

您需要在产品表中包含子类别ID，以便执行以下操作：

<强> ROUTE

Route::get('/show_product/{subcategory_id}','Project\MainController@show_product');

<强> CONTROLLER

// get products with a specific subcategory id

public function show_product($subcategory_id){ 
$subcategories = Subcategory::where('subcategory_id', $subcategory_id)->get();
return view('project.show_product', compact('subcategories '));
}

通过这种方式，您将获得具有特定id子类别

你可能想要这样：

// class to fetch product under subcategories    
public function show_product($id){ 
$subcategories = Subcategory::where('product_id', $id)->get();
return view('project.show_product')->with('subcategories',$subcategories);}

这可以获得具有特定产品ID的所有子类别。但是您需要更改迁移子类别和ADD product_id关系。

// migrations - create_subcategories_table.php
    $table->engine = 'InnoDB';
    $table->increments('id');
    $table->string('name');
    $table->string('image');
    $table->integer('category_id')->unsigned();
    $table->foreign('category_id')->references('id')->on('categories')->onDelete('cascade'); 
    $table->integer('product_id')->unsigned();
    $table->foreign('product_id')->references('id')->on('products')->onDelete('cascade'); 
    $table->timestamps();

您还需要在模型产品和子类别中添加关系，但我不能很好地理解您的结构分类。请举个例子：

第一类
- firs subcategory
- 第二个子类别
第二类
- 其他子类别
- 等

每个产品都有一个类别，类别有更多子类别的孩子，但我不确定你是否想要。屏幕截图可以帮助我们。

Answer 2

// Category  model
public function subcategories(){ return $this->hasMany('App\Subcategory', 'category_id'); }    
public function products() {return $this->hasMany('App\Product', 'subcategory_id');}

// Subcategory model 
public function categories() {return $this->belongsTo('Category');}
public function products() {return $this->hasManyThrough('App\Product'
,'App\Category','subcategory_id','category_id','id');}

// Product model
public function categories() {   return $this->belongsTo('App\Category');}
public function subcategories() {return $this->belongsTo('App\Subcategory');}

// my controller
// class to fetch subcategories under category
public function show_subcategory($name){  
$categories=Category::whereName($name)->get(); 
return view('project.show_subcategory')->with('categories',$categories); 
} 

// class to fetch product under subcategories    
public function show_product($id){ 
$subcategories = Subcategory::whereId($id)->get();
return view('project.show_product')->with('subcategories',$subcategories);}

 //  views - show_subcategory.blade.php
@foreach( $categories as $category)
@foreach( $category->subcategories as $subcategory )    
{{$subcategory->name}}
@endforeach
@endforeach 

//  views - show_product.blade.php
@foreach( $subcategories as $subcategory) 
@foreach( $subcategory->products as $product ) 
{{$product->title}}
@endforeach 
@endforeach

Route::get('/show_subcategory/{name}','Project\MainController@show_subcategory');
Route::get('/show_product/{id}','Project\MainController@show_product');

// migrations - create_subcategories_table.php
$table->engine = 'InnoDB';
$table->increments('id');
$table->string('name');
$table->string('image');
$table->integer('category_id')->unsigned();
$table->foreign('category_id')->references('id')->on('categories')->onDelete('cascade'); 
$table->timestamps();

// migrations - create_products_table.php
$table->engine = 'InnoDB';            
$table->increments('id');
$table->integer('subcategory_id')->unsigned();
$table->foreign('subcategory_id')->references('id')->on('subcategories')->onDelete('cascade'); 
$table->string('title');
$table->text('description');
$table->integer('price');
$table->boolean('availability')->default(1);
$table->string('image');
$table->timestamps();

注意：类show_subcategory运行良好，我可以在类别
下显示子类别
但是show_product类不工作，我无法显示产品   子类别..视图不显示任何错误，不显示   产品

我不知道模型关系或控制器类或视图中的错误在哪里

关系：产品，类别和子类别

2 个答案: