Update object relationship
/custom_objects/objects/{type_name}/{external_id}/object_relationships
Use this endpoint to merge attributes onto an existing object relationship.

Custom Objects is currently in early access. Your workspace must be enabled before the Custom Objects API key permissions appear on Settings > API Keys.
Prerequisites
To use this endpoint, you need an API key with custom_objects.object_relationships.update.
Rate limit
This endpoint is in the Custom Objects write bucket with a default limit of 50 requests per minute.
Path parameters
The following table lists and describes the path parameters for the /custom_objects/objects/{type_name}/{external_id}/object_relationships endpoint.
| Parameter | Required | Data Type | Description |
|---|---|---|---|
type_name |
Required | String | URL object type |
external_id |
Required | String | URL object identifier |
Request parameters
The following table lists and describes the JSON request body parameters for the /custom_objects/objects/{type_name}/{external_id}/object_relationships endpoint.
| Parameter | Required | Data Type | Description |
|---|---|---|---|
rel_kind |
Required | String | Relationship kind |
related_type_name |
Required | String | Related object type |
related_external_id |
Required | String | Related object identifier |
anchor |
Optional | String | source (default) or target |
attributes |
Optional | Object | Relationship attributes to merge |
Example request
This section includes a sample JSON payload and a sample cURL request.
Sample request payload
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{
"rel_kind": "subaccount",
"related_type_name": "account",
"related_external_id": "acct-456",
"anchor": "source",
"attributes": {}
}
Sample cURL request
This example merges attributes into the existing subaccount relationship between acct-123 and acct-456, leaving any attributes you omit unchanged.
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curl --location --request PATCH 'https://rest.iad-01.braze.com/custom_objects/objects/account/acct-123/object_relationships' \
--header 'Authorization: Bearer YOUR_REST_API_KEY' \
--header 'Content-Type: application/json' \
--data-raw '{
"rel_kind": "subaccount",
"related_type_name": "account",
"related_external_id": "acct-456",
"anchor": "source",
"attributes": {}
}'
Response
This section includes a sample successful response and the response fields.
Example success response
The status code 200 could return the following response body.
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{
"object_relationship": {
"rel_kind": "subaccount",
"to_custom_object": {
"type_name": "account",
"external_id": "acct-456",
"attributes": { "name": "Child Account" }
},
"attributes": {}
}
}
Response parameters
The following table lists and describes the fields in a successful response.
| Parameter | Required | Data Type | Description |
|---|---|---|---|
object_relationship |
Required | Object | Updated relationship record |
object_relationship.rel_kind |
Required | String | Relationship kind value |
object_relationship.to_custom_object |
Conditional | Object | Related object when anchor=source |
object_relationship.from_custom_object |
Conditional | Object | Related object when anchor=target |
object_relationship.attributes |
Required | Object | Relationship attributes after merge |
Errors
The following table lists common errors for this endpoint and how to resolve them.
| Status | Cause | Guidance |
|---|---|---|
400 |
Validation error | Confirm rel_kind, anchor, and attributes are valid for the relationship type. |
404 |
Relationship not found (custom-object-relationship-not-found) |
Confirm the source object, related object, and relationship key values all exist. |
401 |
Missing or invalid REST API key | Verify the Authorization header uses Bearer YOUR_REST_API_KEY and that the key is active. |
403 |
API key lacks permission or request is blocked by allowlist | Confirm the key has custom_objects.object_relationships.update and that your source IP is on the key allowlist, if configured. |
429 |
Rate limit exceeded | Retry after X-RateLimit-Reset and reduce request frequency. |