# Is it possible to aggregate write to a self reference table?

**URL:** https://discourse.rom-rb.org/t/is-it-possible-to-aggregate-write-to-a-self-reference-table/537
**Category:** Issues
**Created:** [April 29, 2022, 7:21pm UTC](https://discourse.rom-rb.org/t/is-it-possible-to-aggregate-write-to-a-self-reference-table/537 "2022-04-29T19:21:11Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![codeslinger](https://avatars.discourse-cdn.com/v4/letter/c/e9a140/32.png) [@codeslinger](https://discourse.rom-rb.org/u/codeslinger)
#### Post date: [April 29, 2022, 7:21pm UTC](https://discourse.rom-rb.org/t/is-it-possible-to-aggregate-write-to-a-self-reference-table/537/1 "2022-04-29T19:21:11Z")

</div>

I have a table with a column parent\_id which is a foreign key to itself. Is it possible to combine the relation to itself for create command?

```auto
categories_relation.combine(:categories).command(:create).call(data)

```

My attempts to do this have failed.

Thanks!

---

<div class="post-metadata">

### Author: ![codeslinger](https://avatars.discourse-cdn.com/v4/letter/c/e9a140/32.png) [@codeslinger](https://discourse.rom-rb.org/u/codeslinger)
#### Post date: [May 2, 2022, 3:57pm UTC](https://discourse.rom-rb.org/t/is-it-possible-to-aggregate-write-to-a-self-reference-table/537/2 "2022-05-02T15:57:20Z")

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UPDATE:  
Given this relation…

```auto
class Categories < ROM::Relation[:sql]
  schema(infer: true) do
    associations do
      has_many :categories
    end
  end
end

```

I am able to create records in the db…

```auto
category = {
  name: 'cat 1',
  categories: [{name: 'cat 1.1'}, {name: 'cat 1.2'}]
}
categories.combine(:categories).command(:create).call(category)

```

results in

```auto
 [{:id=>1, :category_id=>nil, :name=>"cat 1"},
 {:id=>2, :category_id=>nil, :name=>"cat 1.1"},
 {:id=>3, :category_id=>nil, :name=>"cat 1.2"}]

```

However the parent association (category\_id) is not getting assigned correctly. The desired result is:

```auto
 [{:id=>1, :category_id=>nil, :name=>"cat 1"},
 {:id=>2, :category_id=>1, :name=>"cat 1.1"},
 {:id=>3, :category_id=>1, :name=>"cat 1.2"}]

```

---

<div class="post-metadata">

### Author: ![solnic](https://yyz1.discourse-cdn.com/flex029/user_avatar/discourse.rom-rb.org/solnic/32/279_2.png) [@solnic](https://discourse.rom-rb.org/u/solnic)
#### Post date: [May 8, 2022, 10:20am UTC](https://discourse.rom-rb.org/t/is-it-possible-to-aggregate-write-to-a-self-reference-table/537/3 "2022-05-08T10:20:50Z")

</div>

This looks like a bug, could you report it in rom-rb/rom-sql?