# Check whether a custom variable exists

Source: https://docs.emelia.io/docs/lists/check-custom-variable

Guide: [Lists & contacts](https://docs.emelia.io/docs/lists.md)

`GET https://api.emelia.io/lists/custom-variable/check`

Tells whether a name is already taken for a schema, either by one of your custom variables (`reason: custom_variable`) or by a standard field (`lead_field` or `company_field`). The name is normalized with the same rule as the creation route and the normalized `technicalName` is returned.

## Authentication

Send your API key in the `Authorization` header: `Authorization: <your API key>`.

## Query parameters

| Name | Type | Required | Description |
|---|---|---|---|
| `technicalName` | string | yes | Name to check. |
| `schema` | enum: `lead`, `company` | yes | `lead` for contact variables, `company` for company variables. |

## Example request

**cURL**

```bash
curl -X GET "https://api.emelia.io/lists/custom-variable/check?technicalName=industryFocus&schema=lead" \
  -H "Authorization: $EMELIA_API_KEY"
```

**JavaScript**

```js
const response = await fetch('https://api.emelia.io/lists/custom-variable/check?technicalName=industryFocus&schema=lead', {
  method: 'GET',
  headers: { Authorization: process.env.EMELIA_API_KEY },
});
console.log(await response.json());
```

**Python**

```python
import os
import requests

response = requests.get(
    "https://api.emelia.io/lists/custom-variable/check?technicalName=industryFocus&schema=lead",
    headers={"Authorization": os.environ["EMELIA_API_KEY"]},
)
print(response.json())
```

## Responses

### 200: Check result.

| Field | Type | Required | Description |
|---|---|---|---|
| `exists` | boolean | yes |  |
| `reason` | enum: `custom_variable`, `lead_field`, `company_field` | no | Present when `exists` is true. |
| `technicalName` | string | yes | The normalized name that was checked. |

```json
{
  "exists": true,
  "reason": "custom_variable",
  "technicalName": "string"
}
```

### 401: Missing, unknown or disabled API key, or the account of the key no longer exists. Note the body shape: `error` and `code`, not `message`.

| Field | Type | Required | Description |
|---|---|---|---|
| `error` | string | yes |  |
| `code` | enum: `AUTH_REQUIRED`, `ACCOUNT_NOT_FOUND` | yes |  |

```json
{
  "error": "string",
  "code": "AUTH_REQUIRED"
}
```

### 422: Missing or invalid query parameter.

| Field | Type | Required | Description |
|---|---|---|---|
| `message` | string | yes | English, human-readable message. |
| `code` | string | no | Stable error code, when available (for example `PAYLOAD_TOO_LARGE`, `INVALID_JSON`, `export_too_large`, `companies_only`, `enrichment_running`). |
| `params` | object | no |  |
| `error` | string | no | Raw internal message (unexpected errors only). |

```json
{
  "message": "\"schema\" must be one of [lead, company]"
}
```

### 500: Unexpected server error. `error`, when present, is a raw internal message: do not parse it. Retry later.

| Field | Type | Required | Description |
|---|---|---|---|
| `message` | string | yes | English, human-readable message. |
| `code` | string | no | Stable error code, when available (for example `PAYLOAD_TOO_LARGE`, `INVALID_JSON`, `export_too_large`, `companies_only`, `enrichment_running`). |
| `params` | object | no |  |
| `error` | string | no | Raw internal message (unexpected errors only). |

```json
{
  "message": "Hmm... Something went wrong. Please try again later."
}
```