Laravel通过（级别/树）关系雄辩一对一

Question

Hi I'm new to laravel (eloquent). I'm trying to make one to one through (level/tree) relationship using eloquent ORM. I have product_category table that have id and parent_id.

This is my product_category table

|-----|--------|-----------|
| id  |  name  | parent_id |
|-----|--------|-----------|
|  1  |  book  |     0     |
|  2  |notebook|     1     |

This is my product table

|----|----------------|-------------|
| id | name           | category_id |
|----|----------------|-------------|
|  1 | super notebook |      2      |

I want to be able to pull parent category information from subcategory_id info in product alone. Is this possible?

When using SQL, this is the query (assume category_id is 2)

SELECT * FROM  `product_category` WHERE  `id` = (SELECT  `parent_id`  FROM `product_category`  WHERE  `id` =  '2' )

Update:

This is my current implementation

<?php

    class Product extends Eloquent {

        public function subcategory()
        {
            return $this->hasOne('ProductCategory');
        }

        public function category()
        {
            // This should get the parent info of the subcategory
            return ProductCategory::find($this->subcategory->parent_id);
        }

    }

Answer 1

A basic 1-2-1 relationship is done like this:

Product model

class Product extends Eloquent {

    public function category()
    {
        return $this->hasOne('Category');
    }

}

Category model

class Category extends Eloquent {

    public function product()
    {
        return $this->belongsTo('Product');
    }

}

Now you can query for data like this:

Product::find(1)->category;

Generated SQL:

select * from products where id = 1

select * from categories where product_id = 1

Basically you should rename your columns to match laravels defaults, else set the keys like $this->hasOne('Category', 'foreign_key');

See docs also