Fresh 2026

Programmatic Nested Writes with /meta

How to use the /meta endpoint to build nested write requests that create multiple related objects in one call, with integration-specific field handling.

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Overview

In an earlier guide to Writing Nested Data, we introduced the concept of writing new entities nested inside another entity in a single POST request to Merge, thereby establishing a relation.

Just like how /meta can be used to programmatically determine writable fields for a Common Model, /meta can also be used to determine writable fields for a nested Common Model.

Refer to our guide to Programmatic Writes with /meta for an introduction to using /meta.

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Request Schema for Nested Common Models

In your /meta response, the request_schema object will have similar properties whether it is for the parent or nested Common Model:

• Common Model fields
• integration_params specifying integration-specific fields
• linked_account_params specifying Linked Account-specific fields

Refer to our documentation of request_schema for more information.

Example - Request Schema

Candidates can accept a nested Application in its applications field.

A GET request to /candidates/meta/post will show supported fields for this nesting in its response:

{
    "request_schema": {
        "type": "object",
        "properties": {
            "model": {
                "type": "object",
                "properties": {
                    "first_name": {
                        "type": "string",
                        "description": "The candidate's first name."
                    },
                    "last_name": {
                        "type": "string",
                        "description": "The candidate's last name."
                    },
                    "email_addresses": {
                        "type": "array",
                        "items": {
                            "type": "object",
                            "properties": {
                                "value": {
                                    "type": "string",
                                },
                                "email_address_type": {
                                    "type": "string",
                                }
                            },
                            "required": ["value"]
                        },
                        "description": "Array of email_addresses objects on ats.Candidate"
                    },
                    "applications": {
                        "type": "array",
                        "items": {
                            "type": "object",
                            "properties": {
                                "applied_at": {
                                    "type": "string",
                                    "description": "When the application was submitted."
                                },
                                "source": {
                                    "type": "string",
                                    "description": "Source of the application."
                                },
                                "integration_params": null,
                                "linked_account_params": null
                            }
                        },
                        "description": "Array of ats.Application objects on ats.Candidate"
                    },
                    "integration_params": null,
                    "linked_account_params": null
                },
                "required": ["first_name", "last_name"]
            }
        }
    }
}

Example - Request Body

In accordance with the response from /meta above, the POST request you would form might have a body like this:

{
  "model": {
    "first_name": "Jane",
    "last_name": "Doe",
    "email_addresses": [
      {
        "value": "jane@merge.dev",
        "email_address_type": "WORK",
      },
      {
        "value": "jane@gmail.com",
        "email_address_type": "PERSONAL",
      }
    ],
    "applications": [
      {
        "applied_at": "2021-10-15T00:00:00Z",
        "source": "Campus recruiting event"
      }
    ]
  }
}