MitMediator.AutoApi 9.0.0-alfa-8

MitMediator.AutoApi

An extension for MitMediator that automatically registers API endpoints and generates strongly-typed HTTP clients from mediator request types, with customizable behavior driven by attributes

• 🚀 Installation
• How It Works
• Examples
• Change default mapping
• Upload and download files
• X-Total-Count Header
• Location header
• Auto client HttpMediator
• Samples
• License

🚀 Installation

1. Add package

# for ASP.NET API projects
dotnet add package MitMediator.AutoApi -v 9.0.0-alfa-8

# for application layer
dotnet add package MitMediator.AutoApi.Abstractions -v 9.0.0-alfa-8

# for client application (MAUI, Blazor, UWP, etc.)
dotnet add package MitMediator.AutoApi.HttpMediator -v 9.0.0-alfa-8

2. Use extension for IEndpointRouteBuilder

var builder = WebApplication.CreateBuilder(args);
// Register handlers and IMediator.
builder.Services.AddMitMediator(); 

var app = builder.Build();

// Automatically maps endpoints based on IRequest
app.UseAutoApi(); 

app.Run();

To use base path "api" and select assemblies to scan: app.UseAutoApi("api", new []{typeof(GetQuery).Assembly});

3. Done! All public requests have endpoints

How It Works

1. Scans all loaded assemblies for IRequest types
2. Dynamically generates and registers endpoints for each match
3. Maps routes using MapPost, MapGet, MapPut, and MapDelete, internally calling IMediator.SendAsync

Transformation Logic

HTTP Method is inferred from the leading verb in the type name:

Resource Name (main tag) is derived from the first noun after the verb, and pluralized:

• Book → /books
• Author → /authors

Route suffix includes any remaining parts of the type name, converted to lowercase and kebab-case:

• Count → /count
• WithAuthor → /with-author

Custom suffix will be added as is

Suffixes Command, Query, and Request are automatically removed from the end

Version prefix (v1, v2, etc.) is prepended to the route as part of the base path

Default version is v1

Examples

GET endpoint with query params

// Api URL: GET /v1/books?limit=1&offset=1&freeText=clara
public struct GetBooksQuery : IRequest<Book[]>
{
    public int? Limit { get; init; }
    
    public int? Offset { get; init; }
    
    public string? FreeText { get; init; }
}

POST endpoint with 201 response

// Api URL: POST /v1/books
public class CreateBookCommand : IRequest<Book>
{
    public string Title { get; init; }
    
    public int AuthorId { get; init; }

    public string GenreName { get; init; }
}

If you need to use rout parameter, implement one of interfaces IKeyRequest<TKey>, IKeyRequest<TKey1,TKey2>, etc. (max 7 keys)

GET endpoint with suffix and key in url

// URL: GET /v1/books/123/cover
public struct GetBookCoverQuery : IRequest<Book>, IKeyRequest<int>
{
    internal int BookId { get; private set; }

    public void SetKey(int key)
    {
        BookId = key;
    }
    
    public int GetKey() => BookId;
}

Change default mapping

Use attributes for the request type to change default mapping

Supported attributes:

When [PatternAttribute] is applied, it overrides the entire route. The base route, version attribute, and tag attribute will be ignored

Examples

GET endpoint with custom tag and custom suffix

// URL: GET /v1/my-books/favorite?limit=1&offset=1&freeText=clara
[Tag("MyBooks")]
[Suffix("favorite")]
public struct GetBooksQuery : IRequest<Book[]>
{
    public int? Limit { get; init; }
    
    public int? Offset { get; init; }
    
    public string? FreeText { get; init; }
}

GET endpoint with version, custom tag, URL pattern and specified HTTP method

// Custom URL pattern overrides base route
// URL: DELETE /with-keys/{key1}/field/{key2}
[Tag("books")]
[Pattern("with-keys/{key1}/field/{key2}")]
[Version("v3")]
[Method(MethodType.Delete)]
public class DoSomeWithBookAndDeleteCommand : IRequest<Book[]>, IKeyRequest<int, Guid>
{
    internal int BookId { get; private set; }
    
    internal Guid GuidId { get; private set; }

    public void SetKey1(int key)
    {
        BookId = key;
    }
    
    public int GetKey1() => BookId;
    
    public void SetKey2(Guid key)
    {
        GuidId = key;
    }
    
    public Guid GetKey2() => GuidId;
}

GET endpoint png file ("image/png")

// Api URL: GET /v1/books/123/сover
[ResponseContentType("image/png")]
public class GetBookCoverQuery: IRequest<byte[]>, IKeyRequest<int>
{
    internal int BookId { get; private set; }
    
    public void SetKey(int key)
    {
        BookId = key;
    }
    
    public int GetKey() => BookId;
}

Upload and download files

For requests implementing IRequest<byte[]>/IRequest<Stream>, or IRequest<FileResponse>/ IRequest<FileStreamResponse>, the response will use "application/octet-stream" by default. To specify a download file name, use the FileResponse or FileStreamResponse response. Use [ResponseContentType("image/png")] attribute for custom content type

When a request implements IFileRequest or inherits from FileRequest, it will be bound using [FromForm]. File parameters fron IFileRequest will be automatically inferred via IFromFile. Apply [DisableAntiforgery] to skip CSRF protection for file upload endpoints or non-browser clients

Examples

GET endpoint text file ("application/octet-stream")

// Api URL: GET /v1/books/123/text
[DisableAntiforgery]
public class GetBookTextQuery: IRequest<byte[]>, IKeyRequest<int>
{
    internal int BookId { get; private set; }
    
    public void SetKey(int key)
    {
        BookId = key;
    }
    
    public int GetKey() => BookId;
}

POST upload and download file with file name

// Api URL: POST /v1/documents/word
public class ImportDocumentWordCommand : FileRequest, IRequest<FileResponse>
{
}

X-Total-Count Header

To include the X-Total-Count header in the HTTP response, implement the ITotalCount interface in your response type. This is useful for paginated endpoints or any scenario where the client needs to know the total number of items available.

public class GetBooksResponse : ITotalCount
{
    public Book[] Items { get; init; }

    private int _totalCount;
    
    public int GetTotalCount() => _totalCount;

    public void SetTotalCount(int totalCount)
    {
        _totalCount = totalCount;
    }
}

When this interface is implemented, MitMediator.AutoApi will automatically include the X-Total-Count header in the response, reflecting the value returned by GetTotalCount()

Location header

To insert the correct ID into the Location header of a 201 Created response, implement the IResourceKey interface in your response type:

// Api URL: POST /books
public class CreateBookCommand : IRequest<CreatedBookResponse>
{
    public string Title { get; init; }
}

// Location Header: /books/{BookId}
public class CreatedBookResponse : IResourceKey
{
    public int BookId { get; private set; }
    
    public string Title { get; private set; }
    
    public string GetResourceKey() => BookId.ToString();
}

If you do not implement the IResourceKey interface, the Location header will default to the format /books/{key}, where {key} is a placeholder string

Auto client HttpMediator

You can reuse your IRequest types to seamlessly send HTTP requests to a server-side API using HttpMediator

HttpMediator supports IClientPipelineBehavior<TRequest, TResponse> for middleware-like extensibility, and IHttpHeaderInjector<TRequest, TResponse> for injecting custom headers per request

Sample usage:

var mediator = new HttpMediator(serviceProvider, baseUrl: "https://api.example.com");
var response = await mediator.SendAsync<MyRequest, MyResponse>(new MyRequest(), cancellationToken);

More

var baseApiUrl = "api";
var httpClientName = "baseHttpClient";
var serviceCollection = new ServiceCollection();
serviceCollection.AddHttpClient(httpClientName, client => { client.BaseAddress = new Uri("https://localhost:7127/"); });
serviceCollection.AddScoped(typeof(IHttpHeaderInjector<,>), typeof(AuthorizationHeaderInjection<,>));
serviceCollection.AddScoped<IClientMediator, HttpMediator>(c => new HttpMediator(c, baseApiUrl, httpClientName));

var provider = serviceCollection.BuildServiceProvider();
var httpMediator = provider.GetRequiredService<IClientMediator>();

var query = new GetBookQuery();
query.SetKey(12);
var data = await httpMediator.SendAsync<GetBookQuery, Book>(query, CancellationToken.None);

public class AuthorizationHeaderInjection<TRequest, TResponse> : IHttpHeaderInjector<TRequest, TResponse> where TRequest : IRequest<TResponse>
{
    public ValueTask<(string, string)?> GetHeadersAsync(CancellationToken cancellationToken)
    {
        var result = ("Authorization", "Bearer token");
        return ValueTask.FromResult<(string, string)?>(result);
    }
}

See samples

MIT License