curl -i -X POST "https://api.box.com/2.0/storage_policy_assignments" \
     -H "authorization: Bearer <ACCESS_TOKEN>" \
     -H "content-type: application/json" \
     -d '{
       "storage_policy": {
         "type": "storage_policy",
         "id": "1434325"
       },
       "assigned_to": {
         "type": "user",
         "id": "9987987"
       }
     }'

client.storage_policy_assignments.create_storage_policy_assignment(
    CreateStoragePolicyAssignmentStoragePolicy(id=policy_id),
    CreateStoragePolicyAssignmentAssignedTo(
        id=user_id, type=CreateStoragePolicyAssignmentAssignedToTypeField.USER
    ),
)

await client.storagePolicyAssignments.createStoragePolicyAssignment({
  storagePolicy: new CreateStoragePolicyAssignmentRequestBodyStoragePolicyField(
    { id: policyId },
  ),
  assignedTo: {
    id: userId,
    type: 'user' as CreateStoragePolicyAssignmentRequestBodyAssignedToTypeField,
  } satisfies CreateStoragePolicyAssignmentRequestBodyAssignedToField,
} satisfies CreateStoragePolicyAssignmentRequestBody);

try await client.storagePolicyAssignments.createStoragePolicyAssignment(requestBody: CreateStoragePolicyAssignmentRequestBody(storagePolicy: CreateStoragePolicyAssignmentRequestBodyStoragePolicyField(id: policyId), assignedTo: CreateStoragePolicyAssignmentRequestBodyAssignedToField(id: userId, type: CreateStoragePolicyAssignmentRequestBodyAssignedToTypeField.user)))

client.getStoragePolicyAssignments().createStoragePolicyAssignment(new CreateStoragePolicyAssignmentRequestBody(new CreateStoragePolicyAssignmentRequestBodyStoragePolicyField(policyId), new CreateStoragePolicyAssignmentRequestBodyAssignedToField(CreateStoragePolicyAssignmentRequestBodyAssignedToTypeField.USER, userId)))

await client.StoragePolicyAssignments.CreateStoragePolicyAssignmentAsync(requestBody: new CreateStoragePolicyAssignmentRequestBody(storagePolicy: new CreateStoragePolicyAssignmentRequestBodyStoragePolicyField(id: policyId), assignedTo: new CreateStoragePolicyAssignmentRequestBodyAssignedToField(id: userId, type: CreateStoragePolicyAssignmentRequestBodyAssignedToTypeField.User)));

{
  "id": "ZW50ZXJwcmlzZV8xMjM0NTY3ODkw",
  "type": "storage_policy_assignment",
  "storage_policy": {
    "id": "11446498",
    "type": "storage_policy"
  },
  "assigned_to": {
    "id": "11446498",
    "type": "file"
  }
}

{
  "type": "error",
  "status": 400,
  "code": "item_name_invalid",
  "message": "Method Not Allowed",
  "context_info": {
    "message": "Something went wrong"
  },
  "help_url": "https://developer.box.com/guides/api-calls/permissions-and-errors/common-errors/",
  "request_id": "abcdef123456"
}