BWHazel.TypedId.EntityFrameworkCore 1.2.0

Typed ID

A library for strongly-typed IDs for your entities!

Using Typed IDs

Typed IDs are available in the BWHazel.TypedId NuGet package.

A typed ID is a generic type which is associated with an entity, for example with the Person and Address types below. Notice how each of the IDs is tied to a specific entity type.

using BWHazel.Data;

public class Person
{
    public Uuid<Person> PersonId { get; set; }
    public Uuid<Address> AddressId { get; set; }
}

public class Address
{
    public Uuid<Address> AddressId { get; set; }
}

These typed IDs can be used in methods:

public bool IsAddressFor(Uuid<Person> personId, Uuid<Address> addressId) { }

These strongly typed IDs will ensure that IDs for different entities will not get confused. For this example, if the Person and Address IDs were swapped in the method call then it would result in a compile-time error.

Additionally, each type can be implicitly interconverted between and comapred with the underlying ID type, for example the Uuid<T> type uses a GUID:

Uuid<Person> personId = person.Id;
Guid personIdAsGuid = personId;

bool idEqualsGuid = personId == personIdAsGuid;
bool guidDoesNotEqualId = personIdAsGuid != personId;

Supported Types

Currently the library supports the following ID types, all in the BWHazel.Data namespace. Please see the detailed documentation, linked in the table below, for more examples.

Use with Entity Framework Core

Entity Framework Core support for Typed IDs is available in the BWHazel.TypedId.EntityFrameworkCore NuGet package.

To use typed IDs in Entity Framework Core they need to be registered with the database context when creating the model in the DbContext.OnModelCreating() method. A helper method is provided to perform the correct mapping to database types for each typed ID in the Microsoft.EntityFrameworkCoew namespace.

Using the example Person and Address entities above this would look like the following. Notice that all uses of a typed ID need to be registered.

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Person>()
        .Property(person => person.PersonId)
        .IsTypedUuid();

    modelBuilder.Entity<Person>()
        .Property(person => person.AddressId)
        .IsTypedUuid();

    modelBuilder.Entity<Address>()
        .Property(address => address.AddressId)
        .IsTypedUuid();
}

For each supported typed ID type, the helper methods are:

A more generic example can be seen here.

Example Programs

Example programs are included to demonstrate how to use Typed IDs and their Entity Framework Core support.

Motivation

IDs provide a unique identifier for entity objects and are often based on GUIDs or integers, e.g. using the example above:

public class Person
{
    public Guid PersonId { get; set; }
    public Guid AddressId { get; set; }
}

public class Address
{
    public Guid AddressId { get; set; }
}

However, this could result in runtime errors if the different IDs get confused, for example in the following method:

public bool IsAddressFor(Guid personId, Guid addressId) { }

What if the person and address IDs were passed into the method in the wrong order? As far as the compiler is concerned, no issue, but at runtime odd behaviour will result.

Hence, typed IDs!

Installation

Typed ID and Entity Framework Core support can be installed from NuGet: