eloquent - Eloquent - 如何使用“Has Many Through”关系？

Question

我有三张表 - products、features 和 product_feature - as

products
    - id
    - name
features
    - id
    - key
product_feature
    - product_id
    - feature_id
    - value

我正在检索产品的所有（键，值）对。SQL 语句是

SELECT key, value FROM products
JOIN product_feature pf
ON pf.product_id = "Product ID"
JOIN features f
ON f.id = pf.feature_id

我如何建立这种关系

// Inside Product model
function features() {
    // Has many through relationship
}

Answer 1

这是一个BelongsToMany关系：

public function features() {
    return $this->belongsToMany(Feature::class, 'product_feature')->withPivot('value');
}

foreach($product->features as $feature) {
    // $feature->key
    // $feature->pivot->value
}