> For the complete documentation index, see [llms.txt](https://docs.lingoql.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.lingoql.com/sub0/apis-abi/accessors.md).

# Accessors

Accessors let Sub0 resolve values at runtime.

They remove hardcoded values from your API definitions.

### Context accessors

Use these to read from the incoming request or environment.

| Accessor    | Reads from            | Example             |
| ----------- | --------------------- | ------------------- |
| `$ENV.`     | Environment variables | `$ENV.JWT_KEY`      |
| `$PAYLOAD.` | Request body          | `$PAYLOAD.email`    |
| `$HEADER.`  | Request headers       | `$HEADER.x-api-key` |

```json
"encryption_key": "$ENV.JWT_KEY"
```

```json
"parameters": ["$PAYLOAD.email"]
```

```json
"x-api-key": "$HEADER.x-api-key"
```

### System accessors

Use these when Sub0 should generate or inject the value.

| Accessor      | Purpose           | Example                    |
| ------------- | ----------------- | -------------------------- |
| `$DATETIME`   | Current timestamp | `created_at`, `updated_at` |
| `$GENERATOR.` | Generated IDs     | `$GENERATOR.UUID`          |

Supported generators:

* `UUID`
* `ULID`
* `KSUID`
* `NANOID`
* `CUID`
* `CUID2`
* `SHORTUUID`
* `SLUGID`
* `BSON`
* `UNIQID`

```json
"parameters": ["name", "email", "$DATETIME"]
```

```json
{
  "generate": "KSUID",
  "for": "id"
}
```

### Protected accessors

Use these after token verification on protected endpoints.

| Accessor      | Purpose                                  | Example         |
| ------------- | ---------------------------------------- | --------------- |
| `$PROTECTED.` | Claims extracted from the verified token | `$PROTECTED.id` |

```json
"upload_folder": "/gallery/$PROTECTED.id"
```

```json
"parameters": ["$PROTECTED.id"]
```

### Rules that matter

* Accessors work anywhere a value is accepted.
* Nested access works for `$PAYLOAD` and `$PROTECTED`.
* If a value cannot be resolved, the request fails safely.

### Next step

Use accessors with [Payload Validation](/sub0/apis-abi/payload-validation.md) and [Authentication](/sub0/apis-abi/authentication.md) to build safe, dynamic endpoints.


---

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