Fields To API

email_address: { $var: fields.email }
first_name: { $var: fields.firstName }
last_name: { $var: fields.lastName }
contact_id: |
  {
    $cond: [
      { $var: fields.id },
      { $var: fields.id },
      null
    ]
  }
custom_fields: |
  {
    $cond: [
      { $and: [
        { $var: parameters.includeCustomFields },
        { $var: fields.customData }
      ]},
      { $var: fields.customData },
      null
    ]
  }

export default async function fieldsToApi({ fields, parameters }) {
  // Transform fieldsSchema to API format
  const apiFields = {
    email_address: fields.email,
    first_name: fields.firstName,
    last_name: fields.lastName,
  }

  // Only include ID for updates, not creates
  if (fields.id) {
    apiFields.contact_id = fields.id
  }

  // Add custom field mapping if enabled
  if (parameters?.includeCustomFields && fields.customData) {
    apiFields.custom_fields = fields.customData
  }

  return apiFields
}

// Your fields:
{
  "id": "123",
  "email": "john@example.com",
  "firstName": "John",
  "lastName": "Doe",
  "fullName": "John Doe"
}

// fieldsToApi transforms to:
{
  "contact_id": "123",
  "email_address": "john@example.com",
  "first_name": "John",
  "last_name": "Doe"
}