---
title: Queries
---

Arc queries return results wrapped in a `QueryResult` envelope that carries the data along with paging metadata and error information. The `QueryResultOperationTransformer` ensures this is accurately reflected in the generated API documentation.

## What the transformer does

For every endpoint whose method is identified as a query (not marked with `[AspNetResult]`), the transformer:

1. Replaces the 200 response schema with `QueryResult`.
2. Adds standard error response schemas for 400, 403, and 500 status codes.
3. Appends paging and sorting query parameters when the method's declared return type passes its enumerable check. Do not assume a task-wrapped collection has identical inference. Model-bound queries use [a separate transformer](/arc/backend/csharp/open-api/model-bound/).

## Pagination and sorting parameters

When a query endpoint returns an enumerable result, the following query parameters are added automatically:

| Parameter | Type | Description |
| --- | --- | --- |
| `sortby` | `string` | Field name to sort by |
| `sortDirection` | `string` (`asc` \| `desc`) | Sort direction |
| `pageSize` | `integer` | Number of items per page |
| `page` | `integer` | Page number (0-based) |

## Response status codes

| Status code | Meaning |
| --- | --- |
| 200 | Query executed successfully |
| 400 | Invalid request or parameters |
| 403 | Forbidden — insufficient permissions |
| 500 | Unexpected server error |

## Opting out

Decorate the action with `[AspNetResult]` to bypass the transformer and expose the raw return type directly. This **controller action fragment** assumes application-owned `Invoice` and `IInvoiceRepository` types:

```csharp
[HttpGet]
[AspNetResult]
public IEnumerable<Invoice> GetInvoices([FromServices] IInvoiceRepository invoices) =>
    invoices.All();
```