如何通过Laravel中的多对多关系访问第三个表？

Question

I am developing an eCommerce Website using Laravel 5.4. Here is database structure:

Products Table: 

ID - Product Name
1  - Test Mobile



Attributes Table

ID - AttributeName
1  - Network



AttributeValues Table

ID - AttributeID - AttributeValue
1  - 1           - 2G
2  - 1           - 3G
3  - 1           - 4G



ProductAttributes Table

ID - AttributeValueID - ProductID
1  - 2                - 1
2  - 3                - 1

Here is the relations:

Product.php

class Product extends Model
{

    public function attributeValues() {
        return $this->belongsToMany('App\AttributeValue', 'attribute_product');
    }

}

Attribute.php

class Attribute extends Model
{
    public function products() {
        return $this->belongsToMany('App\Product');
    }


    public function values() {
        return $this->hasMany(AttributeValue::class);
    }
}

AttributeValue.php

class AttributeValue extends Model
{

    public $timestamps = false;

    public function attribute() {
        return $this->belongsTo( App\Attribute::class );
    }

}

I can access the Product Attributes Values by using the following code:

$p = App\Product::find(1);
$p->attributeValues;

Through this code I am able to retrieve Product Attribute values. But I can access the attributeValues along with the Attribute names? In other words how I can access the Attribute table along with the attribute values? Which relationship will be used?

Any ideas? suggestions?

Answer 1

I once did something like this with load method ie

$p = App\Product::find(1);
$p->load('attributeValues.attribute');

So for every attributeValue , get corresponding attribute It should work for you too...

PS: I can't bet this is the best way to do it. But I have used this technique for a Laravel 5.2 project

Answer 2

你正在使用错误的地方，使用与描述模型中的关系相同的名称。

$product = App\Product::with('attributeValues.attribute')->find(1)

Answer 3

If Product belonsToMany AttributeValue, AttributeValue Should belongsToMany Product.

Product Model:

public function attributeValues() {
        return $this->belongsToMany('App\AttributeValue', 'attribute_product');
    }

AttributeValue Model:

public function products() {
        return $this->belongsToMany('App\Product');
    }

public function attribute() {
    return $this->belongsTo( App\Attribute::class );
}

Attribute Model:

  public function values() {
        return $this->hasMany(AttributeValue::class);
    }

And,

$product = App\Product::find(1);
foreach($product->attributeValues as $attributeValue)
{
   echo $attributeValue;
   echo $attributeValue->attribute;
}