> ## Documentation Index
> Fetch the complete documentation index at: https://archie.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Data Types

> Data Types are reusable named enums you can apply to fields across tables — defined once, applied everywhere.

A Data Type is a reusable named enum — a fixed list of values that you define once and apply to fields across your data model. Instead of declaring `DRAFT`, `PUBLISHED`, `ARCHIVED` separately on every field that needs those statuses, you create one `post_status_enum` Data Type and reference it wherever it's needed.

When you update a Data Type, every field that uses it inherits the change.

## When to use a Data Type

Use a Data Type when the same list of values needs to stay consistent across multiple fields or tables:

* A `status_enum` shared by `posts.status`, `comments.status`, and `pages.status`
* A `priority_enum` shared across every table that has a priority column
* A `currency_enum` shared by `orders.currency`, `invoices.currency`, and `payments.currency`

If the list lives on exactly one field and you don't expect to reuse it, use an [inline enum](/features/backend/data-model/fields/inline-enum) instead.

## Creating a Data Type

<Steps>
  <Step title="Open the Data Model sidebar">
    Find the **+ Add Table** button at the top of the sidebar.
  </Step>

  <Step title="Open the dropdown">
    Click the dropdown arrow next to **+ Add Table**.
  </Step>

  <Step title="Choose Add Data Type">
    Select **Add Data Type** from the menu. The Data Type editor opens.
  </Step>

  <Step title="Name and describe">
    Give the Data Type a unique, lowercase identifier. The convention is to suffix the name with `_enum` (for example, `course_status_enum`) so it's clear at a glance what it is.
  </Step>

  <Step title="Add values">
    Enter the allowed values in upper snake case (for example, `IN_PROGRESS`, `COMPLETED`). Add as many rows as you need.
  </Step>

  <Step title="Save">
    The Data Type appears in the **Data Types** section of the sidebar and becomes available to any user-defined field.
  </Step>
</Steps>

<img src="https://mintcdn.com/archie-e998dbf6/GdaYz5W-YpQoJXsQ/features/backend/data-model/data-builder-add-data-type.png?fit=max&auto=format&n=GdaYz5W-YpQoJXsQ&q=85&s=8df3daf17173768474e9b3100c6bec7d" alt="Add Data Type button and modal" width="1866" height="853" data-path="features/backend/data-model/data-builder-add-data-type.png" />

<img src="https://mintcdn.com/archie-e998dbf6/GdaYz5W-YpQoJXsQ/features/backend/data-model/data-builder-data-type-sidebar.png?fit=max&auto=format&n=GdaYz5W-YpQoJXsQ&q=85&s=9f0832cf3c70b9f960d496b707193dc2" alt="Data Type sidebar listing" width="1866" height="853" data-path="features/backend/data-model/data-builder-data-type-sidebar.png" />

<img src="https://mintcdn.com/archie-e998dbf6/GdaYz5W-YpQoJXsQ/features/backend/data-model/data-builder-data-type-enum.png?fit=max&auto=format&n=GdaYz5W-YpQoJXsQ&q=85&s=d23b10db1102b09da49806cc09d76660" alt="Data Type enum values configuration" width="1866" height="853" data-path="features/backend/data-model/data-builder-data-type-enum.png" />

## Applying a Data Type to a field

On any table's **Schema** tab, add a [user-defined field](/features/backend/data-model/fields/user-defined) and pick the Data Type from the **Enum Type** dropdown. The field will only accept values from that Data Type's list.

## Examples

| Data Type name           | Sample values                                |
| ------------------------ | -------------------------------------------- |
| `course_status_enum`     | `OPEN`, `CLOSED`, `IN_PROGRESS`, `CANCELLED` |
| `grade_type_enum`        | `A`, `B`, `C`, `D`, `F`, `INCOMPLETE`        |
| `resource_type_enum`     | `VIDEO`, `PDF`, `QUIZ`, `ASSIGNMENT`         |
| `attendance_status_enum` | `PRESENT`, `ABSENT`, `LATE`, `EXCUSED`       |

## Why Data Types over inline enums

* **Standardization** — every field using `status_enum` accepts the exact same list of values, eliminating drift between tables.
* **Single source of truth** — when business rules change, you update the Data Type once and every field that uses it is updated.
* **Predictable APIs** — the GraphQL schema exposes one shared enum type instead of many lookalike ones.

## How it appears in the API

The Data Type is generated as a single enum type in the GraphQL schema. Every field that uses it gets the same typed value, with autocompletion and validation on the client. See the [GraphQL API Explorer](/features/backend/graphql-api-explorer/overview) to inspect the generated types.

## Permissions

Data Types are not access-controlled — they're shape definitions. Read and write access to fields that use them is governed in [Role-Based Access](/features/backend/app-services/role-based-access).

## FAQ

<AccordionGroup>
  <Accordion title="What happens if I add a value to a Data Type?">
    Every field using the Data Type immediately accepts the new value. Existing rows are untouched. This is safe and the most common kind of change.
  </Accordion>

  <Accordion title="What happens if I remove a value?">
    Any rows that still hold the removed value will fail validation on update. Migrate affected rows to a different value before removing it from the Data Type.
  </Accordion>

  <Accordion title="Can I rename a value?">
    Renaming changes the Data Type but does not rewrite existing rows. Update affected rows to the new value after renaming.
  </Accordion>

  <Accordion title="Can I convert an inline enum into a reusable Data Type later?">
    Yes. Create the Data Type with the same values, then change the field's type from inline enum to user-defined and pick the new Data Type. Existing values that match carry over.
  </Accordion>

  <Accordion title="Can two Data Types share the same name?">
    No. Data Type names are unique within a project. Pick names that describe the domain meaning (`order_status_enum`) rather than the column they happen to be attached to.
  </Accordion>
</AccordionGroup>