## Register a requisite link

`POST /v1/requisite-links`

Creates or updates the link between a requisite and an owner entity. If a link for the given `entityTypeId` and `entityId` pair already exists, it is overwritten in full.

## Request fields (body)

| Field | Type | Required | Description |
|------|-----|:-----:|---------|
| `entityTypeId` | number | yes | Link owner type. Values — [Link fields](/docs/entities/requisite-links/fields) |
| `entityId` | number | yes | Owner entity ID. The source depends on the type — see the same reference |
| `requisiteId` | number | yes | Client requisite ID. Source: [`GET /v1/requisites`](/docs/entities/requisites/list). Pass `0` to skip linking |
| `bankDetailId` | number | yes | Client bank detail ID. Source: [`GET /v1/bank-details`](/docs/entities/bank-details/list). Pass `0` to skip linking |
| `mcRequisiteId` | number | yes | Your company's requisite ID. Source: [`GET /v1/requisites`](/docs/entities/requisites/list). Pass `0` to skip linking |
| `mcBankDetailId` | number | yes | Your company's bank detail ID. Source: [`GET /v1/bank-details`](/docs/entities/bank-details/list). Pass `0` to skip linking |

## Examples

### curl — personal key

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/requisite-links" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "entityTypeId": 2,
    "entityId": 3773,
    "requisiteId": 45,
    "bankDetailId": 12,
    "mcRequisiteId": 3,
    "mcBankDetailId": 7
  }'
```

### curl — OAuth application

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/requisite-links" \
  -H "X-Api-Key: YOUR_APP_KEY" \
  -H "Authorization: Bearer USER_SESSION_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "entityTypeId": 2,
    "entityId": 3773,
    "requisiteId": 45,
    "bankDetailId": 12,
    "mcRequisiteId": 3,
    "mcBankDetailId": 7
  }'
```

### JavaScript — personal key

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/requisite-links', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    entityTypeId: 2,
    entityId: 3773,
    requisiteId: 45,
    bankDetailId: 12,
    mcRequisiteId: 3,
    mcBankDetailId: 7,
  }),
})

const { success, data } = await res.json()
console.log('Registered link for entityId:', data.entityId)
```

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/requisite-links', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    entityTypeId: 2,
    entityId: 3773,
    requisiteId: 45,
    bankDetailId: 12,
    mcRequisiteId: 3,
    mcBankDetailId: 7,
  }),
})

const { success, data } = await res.json()
```

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `success` | boolean | Always `true` on success |
| `data` | object | Registration result |
| `data.entityTypeId` | number | The entity type that was passed |
| `data.entityId` | number | The entity ID that was passed |
| `data.registered` | boolean | Always `true` on success |

The links themselves are not returned in the response. To see the stored values, read the link via [`GET /v1/requisite-links/:entityTypeId/:entityId`](/docs/entities/requisite-links/get).

## Response example

HTTP status: `201 Created`

```json
{
  "success": true,
  "data": {
    "entityTypeId": 2,
    "entityId": 3773,
    "registered": true
  }
}
```

## Error response example

400 — not all six fields were provided:

```json
{
  "success": false,
  "error": {
    "code": "MISSING_FIELDS",
    "message": "POST /v1/requisite-links requires entityTypeId, entityId, requisiteId, bankDetailId, mcRequisiteId and mcBankDetailId in the body (use 0 for ids you don't want to link). Missing: requisiteId, bankDetailId, mcRequisiteId, mcBankDetailId. Raw UPPER_SNAKE names are accepted too: ENTITY_TYPE_ID, ENTITY_ID, REQUISITE_ID, BANK_DETAIL_ID, MC_REQUISITE_ID, MC_BANK_DETAIL_ID."
  }
}
```

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 400 | `MISSING_FIELDS` | One or more of the six required fields is missing |
| 400 | `INVALID_REQUEST` | The request body is not an object |
| 404 | `ENTITY_NOT_FOUND` | No requisite or bank detail exists with the given ID |
| 422 | `BITRIX_ERROR` | The link was rejected — for example, a requisite cannot be linked to a deal that has no client selected |
| 403 | `SCOPE_DENIED` | API key lacks the `crm` scope |
| 401 | `TOKEN_MISSING` | API key has no configured tokens |

Full list of common API errors — [Errors](/docs/errors).

## Known specifics

**`0` means "do not link", not a reference to an object with ID zero.** All six fields must be present in the body, but a value of `0` in any of the four identifiers means an empty link. A link whose four identifiers are all `0` is registered and returns `201`.

**Registration overwrites the link in full.** A repeat call replaces all four links with the values from the request body: wherever `0` is passed, the link is cleared. To change one link and keep the rest, use [`PATCH /v1/requisite-links/:entityTypeId/:entityId`](/docs/entities/requisite-links/update).

**The client requisite must belong to the deal's client.** To link `requisiteId` to a deal, the deal must have a contact or company selected — the owner of that requisite. Your company's own requisites — `mcRequisiteId` and `mcBankDetailId` — do not depend on the deal's client.

**On rejection, the previous link stays untouched.** If at least one identifier fails validation, none of the request values are applied.

## See also

- [Link fields](/docs/entities/requisite-links/fields)
- [Update a link](/docs/entities/requisite-links/update)
- [Delete a link](/docs/entities/requisite-links/unregister)
- [List links](/docs/entities/requisite-links/list)
- [Requisites](/docs/entities/requisites)
- [Bank details](/docs/entities/bank-details)
- [Batch](/docs/batch)