Introduction

StrongTypeId prevents developer from using the wrong Id in their code. Compatible with Asp.Net Core routing, Entity Framework Core, NHibernate, System.Text.Json, Newtonsoft.Json, GraphQL.Net and HotChocolate

Record idea and TypeConverters are from Thomas Levesque blog

Example :

public class Product
{
    public int Id { get; set; }
}

public class Account
{
    public int Id { get; set; }
}

public void CreateItem(int productId, int accountId);

// Wrong but it compiles 😨
❎ CreateItem(account.Id, product.Id);

//////////////////////////////////////////
// With StrongTypeId, you would have
//////////////////////////////////////////

public record ProductId(int Value) : StrongTypeId(Value);

public class Product
{
    public ProductId Id { get; set; }
}

public record AccountId(int Value) : StrongTypeId(Value);

public class Account
{
    public AccountId Id { get; set; }
}

public void CreateItem(ProductId productId, AccountId accountId);

// Will not compile 👍
❌ CreateItem(account.Id, product.Id);

How to use ?

Install-Package StrongTypeId

Simply declare your identifiers like this :

public record ProductId(int Value) : StrongTypeId(Value)
{
    // Before C# 10 and .Net6.0
	// Needed if you wanna use your StrongTypeId in route parameters
	// Or you can use StrongTypeId.Generators to generate it
	public override string ToString() => base.ToString();
}

And use it like that :

public class Product
{
    public ProductId Id { get; set; }
}

What about json serialization ?

This library is compatible with Newtonsoft.Json and System.Text.Json. We provide converters that will serialize the strong type to his Id type. Also it will deserialize Id type to strong type.

Newtonsoft.Json

Install-Package StrongType.Newtonsoft.Json

In your Startup.cs, ConfigureServices

services.AddMvc().AddNewtonsoftJson(options =>
    {
        // Add StrongTypeId Converter
        options.SerializerOptions.Converters.Add(new StrongTypeIdJsonConverter());
    });

System.Text.Json

Install-Package StrongTypeId.System.Text.Json

In your Startup.cs, ConfigureServices

services.AddMvc()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.Converters.Add(new StrongTypeIdJsonConverterFactory());
    });

What about my ORM ?

This library is compatible with NHibernate. Entity Framework contribution are welcome !

Fluent NHibernate

Install-Package StrongTypeId.FluentNhibernate

var fluentCfg = Fluently.Configure()
    .Mappings(m =>
    {
        m.FluentMappings.Conventions.Add<ConventionStrongTypeId>();
    });

Entity Framework Core

Install-Package StrongTypeId.EFCore

In your model's OnConfiguring method

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder
        .UseStrongTypeIdConventions();

EFCore and Postgres

When using Npgsql, StrongTypeId (by default) cannot be auto-increment. We need to change Npgsql conventions to do that :

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder
        .UseCustomStrongTypeNpgsqlBuilder()

AspNet

When using strong type id in your route like this :

var productId = new ProductId(5);
RedirectToAction("Index", new { id = productId });

The generated url, will use productId.ToString() in the Url. By default C# create a ToString() method on record that will display :

ProductId { Value = 5 }

And the url will look like this :

/Product/Index/ProductId { Value = 5 } instead of /Product/Index/5

To prevent this, you have to override ToString() or use the source generator that will do it for you.

GraphQL.Net

Register specific ScalarType for GraphQL.Net

Install-Package StrongTypeId.GraphQL

Inside your Schema :

using StrongType.GraphQL;

public class MySchema : Schema
{
	public MySchema(IHttpContextAccessor httpContextAccessor)
		: base(httpContextAccessor.HttpContext.RequestServices)
	{
		this.AddStrongTypeId<ProductId>();
	}
}

GraphQL HotChocolate

Install-Package StrongTypeId.HotChocolate

In your Startup.cs, ConfigureServices :

using StrongType.HotChocolate;

...

services.AddGraphQLServer()
	.BindStrongTypeId<ProductId>()

or if you wanna add all types automatically :

services.AddGraphQLServer()
	.BindStrongTypeInAssembly(typeof(ProductId).Assembly)

Generators

Before C# 10 and .Net6.0 the ToString method could not be sealed. So we needed a generator to create the right ToString method

Install-Package StrongTypeId.Generators

Then you must declare your record as partial :

public partial record ProductId(int Value) : StrongTypeId(Value);

And the generator will generate the ToString() method at compilation.