ASP.NET Core polymorphic model binding

A polymorphic model binder for ASP.NET Core. Inspired on Microsoft Docs.

Getting Started

PolymorphicModelBinder can be installed using the Nuget package manager or the dotnet CLI.

dotnet add package PolymorphicModelBinder

Usage

// Models
public abstract class Pet
{
    public string Name { get; set; }
}
public class Dog : Pet
{
    public bool CanBark { get; set; }
}
public class Cat : Pet
{
    public bool CanMeow { get; set; }
}

// Add polymorphic model binder
builder.Services.AddPolymorphicModelBinder(options =>
{
    options.Add<Pet>(polymorphicBuilder =>
    {
        polymorphicBuilder.AddFromTypeInValue<Dog>();
        polymorphicBuilder.AddFromTypeInValue<Cat>();
    });
});

// Controller
public class HomeController : Controller
{
    [HttpGet]
    public IActionResult Index(string type = "Dog")
    {
        Pet pet = type switch
        {
            "Dog" => new Dog(),
            "Cat" => new Cat(),
            _ => throw new ArgumentOutOfRangeException(nameof(type))
        };
        return View(new SampleViewModel(pet));
    }
    
    [HttpPost]
    public IActionResult Index(SampleViewModel viewModel) => View(viewModel);
}

// View
@using PolymorphicModelBinder.Html
@model SampleViewModel

@using (Html.BeginForm(FormMethod.Post))
{
    @Html.PolymorphicTypeInValueFor(x => x.Pet)
    @Html.PolymorphicEditorFor(x => x.Pet)
    <button type="submit" class="btn btn-primary btn-lg">Submit</button>
}

Samples

• Polymorphic model as root model
• Polymorphic model as property
• Dynamic polymorphic list
• Polymorphic model with discriminator field

Roadmap

If you want to see a new feature feel free to create a new issue. Here are some features which are planned when there is enough enthusiasm for this feature.

• Basic implementation with a type in value and discriminator.
• Allow to use @Html.PolymorphicEditorFor() for IEnumerable models.
• Probably better documentation for usages.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

License

MIT