---
title: Controller-based queries
description: Use Arc query results with ASP.NET Core MVC routing and binding.
---


<!-- Copyright (c) Cratis. All rights reserved.
Licensed under the MIT license. See LICENSE file in the project root for full license information. -->

Use a controller when your query needs MVC routing, model binding, or authorization policies. Unlike a [model-bound query](/arc/backend/csharp/queries/model-bound/), the method does not need to live on the type it returns.

## Start with an MVC GET action

This controller example uses the [shared `AccountId` and `AccountName` concepts](/arc/backend/csharp/queries/model-bound/#model-account-identities-and-names) with an ASP.NET Core Arc host, MVC, and the configured Arc MongoDB provider. Use this `DebitAccount` declaration instead of the model-bound alternative. No Chronicle integration is required.

```csharp
using System.Collections.Generic;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using MongoDB.Driver;

namespace Banking.Accounts;

public record DebitAccount(AccountId Id, AccountName Name, decimal Balance);

[Authorize(Roles = "AccountReader")]
[Route("api/accounts")]
public class AccountsController(IMongoCollection<DebitAccount> collection) : ControllerBase
{
    [HttpGet]
    public IEnumerable<DebitAccount> AllAccounts() => collection.Find(_ => true).ToList();
}
```

With authentication and authorization middleware configured, the MVC authorization attribute protects this action. Arc's `QueryActionFilter` handles **GET** actions: it establishes query context, processes MVC model-state errors, renders the returned data, applies interception, and wraps it in [QueryResult](/arc/backend/csharp/queries/query-pipeline/#query-result-metadata).

This is not the model-bound `IQueryPipeline` filter chain. Do not assume model-bound custom filters run for a controller action, or that Arc's GET query wrapper applies to a POST action.

## Choose the next step

- [Route templates](/arc/backend/csharp/queries/controller-based/route-templates/): bind identifiers from route values.
- [Query arguments](/arc/backend/csharp/queries/controller-based/query-arguments/): bind scalar values, arrays, and MVC DTOs.
- [Dependency injection](/arc/backend/csharp/queries/controller-based/dependency-injection/): resolve application services.
- [Return types](/arc/backend/csharp/queries/controller-based/return-types/): understand wrapping, nulls, and explicit MVC responses.
- [Paging](/arc/backend/csharp/queries/controller-based/paging/): return `IQueryable<T>` for renderer-based paging.
- [Observable queries](/arc/backend/csharp/queries/controller-based/observable-queries/): expose a producer over direct SSE or WebSocket.

The [proxy generator](/arc/backend/csharp/proxy-generation/) creates client types from supported controller query declarations. For raw MVC responses, see [without wrappers](/arc/backend/csharp/asp-net-core/without-wrappers/); opting out changes the contract a standard Arc query client expects.