twenty/packages/twenty-docs/developers/extend/apps/data/system-fields.mdx

---
title: Targeting System Fields
description: Reference auto-created system fields like createdAt or updatedAt from views and other entities with getFieldUniversalIdentifier.
icon: "gears"
---

Every object in Twenty ships with a set of **system fields** that you never declare yourself. They are created automatically by the server when the object is provisioned:

`id`, `createdAt`, `updatedAt`, `deletedAt`, `createdBy`, `updatedBy`, `position`, `searchVector`

Because you don't declare these fields with [`defineField()`](/developers/extend/apps/data/extending-objects), there's no `universalIdentifier` constant for you to import. So how do you reference `createdAt` as a column in a [view](/developers/extend/apps/layout/views)?

## The problem

Since Twenty 2.19, a system field's universal identifier is **derived deterministically** by the server from three inputs: the application universal identifier, the object universal identifier, and the field name. Inventing an id and hardcoding it won't work: it matches nothing on the server, and the sync rejects the dangling reference:

```
Dev sync failed: viewField: INVALID_VIEW_DATA: Field metadata not found
```

## The solution

<Note>
  `getFieldUniversalIdentifier` is available from `twenty-sdk` 2.21 onward.
</Note>

Use `getFieldUniversalIdentifier` to resolve the exact same value the server uses. It takes the three inputs and returns the field's universal identifier:

```ts
import { getFieldUniversalIdentifier } from 'twenty-sdk/define';

const createdAtFieldId = getFieldUniversalIdentifier({
  applicationUniversalIdentifier: APPLICATION_UNIVERSAL_IDENTIFIER,
  objectUniversalIdentifier: MY_OBJECT_UNIVERSAL_IDENTIFIER,
  name: 'createdAt',
});
```

- `applicationUniversalIdentifier` is your app's identifier, the one you pass to [`defineApplication()`](/developers/extend/apps/config/application).
- `objectUniversalIdentifier` is the identifier of the object the field belongs to.
- `name` is the system field name, one of the values listed above.

## Example: a createdAt column in a view

The typical case is adding a `createdAt` column to a view of one of your custom objects. Resolve the field id and reference it as any other `fieldMetadataUniversalIdentifier`:

```ts src/views/example-view.ts
import {
  defineView,
  getFieldUniversalIdentifier,
} from 'twenty-sdk/define';

const APPLICATION_UNIVERSAL_IDENTIFIER =
  '0b04e15c-27b2-4741-9046-b32e07469072';
const MY_OBJECT_UNIVERSAL_IDENTIFIER =
  'c782b61c-70fd-4c88-9cd6-4e61ab8d7591';

export default defineView({
  universalIdentifier: '70f10d44-144a-4da8-8c6f-3ec2422138c0',
  name: 'All records',
  objectUniversalIdentifier: MY_OBJECT_UNIVERSAL_IDENTIFIER,
  icon: 'IconList',
  position: 0,
  fields: [
    {
      universalIdentifier: '75a90bc4-d901-4df4-85e0-af29db5e0104',
      fieldMetadataUniversalIdentifier: getFieldUniversalIdentifier({
        applicationUniversalIdentifier: APPLICATION_UNIVERSAL_IDENTIFIER,
        objectUniversalIdentifier: MY_OBJECT_UNIVERSAL_IDENTIFIER,
        name: 'createdAt',
      }),
      position: 0,
      isVisible: true,
      size: 200,
    },
  ],
});
```

The same resolved id works anywhere a `fieldMetadataUniversalIdentifier` is expected: view fields, filters, sorts, groups, and page-layout widgets.

<Note>
  Resolve the id, don't hardcode it. Because the server derives the value from
  the application id, the object id and the field name, calling
  `getFieldUniversalIdentifier` keeps your reference correct even if those
  inputs change, and avoids drift if the derivation ever evolves.
</Note>

## System relation fields

<Note>
  `getSystemRelationFieldUniversalIdentifier` is available from `twenty-sdk`
  2.23 onward and requires a Twenty server on 2.23 or later.
</Note>

Besides the scalar system fields above, the server also provisions four **system relation fields** on every object: `timelineActivities`, `attachments`, `noteTargets` and `taskTargets`, each pointing at the matching standard relation object.

These fields are not resolved with `getFieldUniversalIdentifier`: their identifier is derived **name-free**, from the object hosting the field and the object the field points to. That way renaming an object never changes the identifiers of its relation fields.

Use `getSystemRelationFieldUniversalIdentifier` to resolve them:

```ts
import {
  getSystemRelationFieldUniversalIdentifier,
  STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS,
} from 'twenty-sdk/define';

// rocket.attachments — the relation field hosted on your custom object
const rocketAttachmentsFieldId = getSystemRelationFieldUniversalIdentifier({
  applicationUniversalIdentifier: APPLICATION_UNIVERSAL_IDENTIFIER,
  objectUniversalIdentifier: ROCKET_OBJECT_UNIVERSAL_IDENTIFIER,
  relationTargetObjectUniversalIdentifier:
    STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS.attachment.universalIdentifier,
});
```

- `objectUniversalIdentifier` is the object **hosting** the field.
- `relationTargetObjectUniversalIdentifier` is the object the field **points to**.

The direction is encoded by the argument order. To resolve the reverse side (e.g. `attachment.targetRocket`, the morph field the server creates on the standard relation object), swap the two:

```ts
// attachment.targetRocket — the reverse morph field on Attachment
const attachmentTargetRocketFieldId =
  getSystemRelationFieldUniversalIdentifier({
    applicationUniversalIdentifier: APPLICATION_UNIVERSAL_IDENTIFIER,
    objectUniversalIdentifier:
      STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS.attachment.universalIdentifier,
    relationTargetObjectUniversalIdentifier: ROCKET_OBJECT_UNIVERSAL_IDENTIFIER,
  });
```

As with scalar system fields, the resolved id works anywhere a `fieldMetadataUniversalIdentifier` is expected.

## Standard Twenty objects

For a **standard** Twenty object (Person, Company, Opportunity, …), you don't need to derive anything: the system field identifiers are pre-computed constants you can import directly.

```ts
import { STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS } from 'twenty-sdk/define';

// STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS.company.fields.createdAt.universalIdentifier
// STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS.person.fields.updatedAt.universalIdentifier
```

Reach for `getFieldUniversalIdentifier` when the object is one **your app** defines with [`defineObject()`](/developers/extend/apps/data/objects), where no such constant exists.

<Note>
  `name` is a **default** field, not a system field. It keeps its own hardcoded
  universal identifier and is not resolved through
  `getFieldUniversalIdentifier`. On objects you define, reference the
  `name` field by the identifier you gave it in `defineObject()`.
</Note>