Laravel雄辩的自我加入父母子女 [英] Laravel Eloquent Self Join Parent Child

问题描述

class Product_category extends Model
{
    //
    protected $table='PRODUCT_CATEGORIES';
    public $timestamps = false;


    public function getParentCategory() {
        return $this->hasOne(self::class, 'id', 'parent_id');
    }.


    public function getChildCategories(){
        return $this->hasMany(self::class, 'parent_id','id');
    }

我能够通过使用getChildeCategories来检索表的所有子记录，但无法检索特定类别的Parent. 它总是给我空值.

I am able to retrieve all child records of table by making use of getChildeCategories but not able to retrieve Parent of particular category. It always gives me null.

推荐答案

这称为一对多关系，hasMany关系的逆是belongsTo方法，您的getParentCategory()应为:

It's called one-to-many relationship, the inverse of a hasMany relationship is belongsTo method, your getParentCategory() should be:

public function getParentCategory() {
    return $this->belongsTo(self::class, 'parent_id');
}

public function getChildCategories(){
    return $this->hasMany(self::class, 'parent_id');
}

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