Muslim.Result 10.0.1

Muslim.Result

One result type for every operation in .NET 10: the data on success, the errors on failure, and the page numbers when the data is a list. Your API always answers in the same shape.

dotnet add package Muslim.Result

Quick start

Return a Result<T> from your service:

using Muslim.Result;
using Muslim.Validator;

public class ProductService(ShopContext db, IServiceProvider services)
{
    public async Task<Result<ProductDto>> GetAsync(int id)
    {
        var product = await db.Products.FindAsync(id);

        return product is null
            ? Result<ProductDto>.Fail("Product not found")
            : Result<ProductDto>.Success(new ProductDto { Id = product.Id, Name = product.Name });
    }

    public async Task<Result<int>> CreateAsync(CreateProductDto dto, CancellationToken ct)
    {
        var (errors, isValid) = await ValidateResult.ErrorsAsync(dto, services, ct);
        if (!isValid)
            return Result<int>.ValidatorFail(errors);

        var product = new Product { Name = dto.Name, Price = dto.Price };
        db.Products.Add(product);
        await db.SaveChangesAsync(ct);

        return Result<int>.Success(product.Id);
    }
}

Send it back from the endpoint:

app.MapGet("/products/{id:int}", async (int id, ProductService service) =>
{
    var result = await service.GetAsync(id);
    return result.IsSuccess ? Results.Ok(result) : Results.NotFound(result);
});

The client always gets the same fields:

{
  "response": { "id": 7, "name": "Coffee" },
  "error": null,
  "validatorError": null,
  "isSuccess": true,
  "page": null,
  "filter": null
}

{
  "response": null,
  "error": [ "Product not found" ],
  "validatorError": null,
  "isSuccess": false,
  "page": null,
  "filter": null
}

Creating results

You can add errors to an existing result. Either call marks it as failed:

result.AddError("Stock is not enough");
result.AddValidateError("Quantity", "Quantity must be at least 1");

Lists and paging

Pass the total count and page size, and the result works out the number of pages:

var page = filter.ToPagedResult(db.Products.AsNoTracking());   // Muslim.Filter

return Result<IReadOnlyList<Product>>.Success(page.Items, count: page.TotalCount, pageSize: page.PageSize);

{
  "response": [ ... ],
  "isSuccess": true,
  "page": { "count": 21, "numberOfPages": 3, "pageSize": 10 }
}

A page size of 0 means "not paged", and page is left empty. A negative count or page size throws ArgumentOutOfRangeException.

Chaining

Map changes the value, Bind calls the next step, and Match turns the result into one final value. On failure, Map and Bind skip their code and carry the errors forward.

var result = await service.GetAsync(id);

var message = result
    .Map(product => product.Name)
    .Bind(name => name.Length > 0
        ? Result<string>.Success(name)
        : Result<string>.Fail("Product has no name"))
    .Match(
        onSuccess: name   => $"Found {name}",
        onFailure: failed => string.Join(", ", failed.Error ?? []));

MapAsync, BindAsync and MatchAsync do the same with async code. Page and filter data are kept through Map.

To return the same status and errors with a different value, use To:

Result<string> nameResult = productResult.To(productResult.Response?.Name ?? "");

Good to know

• Create(value) checks only for null, an empty string or an empty list. 0, false and a DTO with empty properties all count as found.
• Create reads the first item of a sequence to see if it is empty. For a stream or a sequence that must not be read twice, use Success instead, or call ToList() first.
• Exception(ex) puts the exception message in the response. Decide whether that message is safe to show your users.
• ResultPage lives in the Muslim.HandelResult namespace.

Related packages

Coding-agent guidance

When you build a project that uses this package, a short guide for AI coding agents is copied to .agents/skills/muslim-result/ at the root of your repository. Agents that read skills from .agents/skills, such as Codex and GitHub Copilot in VS Code, use it to write correct code against this package. Your own files and other skills are never touched, and nothing is deleted automatically.

To turn it off, add this to your project or Directory.Build.props:

<PropertyGroup>
  <MuslimResultGenerateAgentSkills>false</MuslimResultGenerateAgentSkills>
</PropertyGroup>

License

See LICENSE.txt.