Strongly makes creating strongly-typed values as easy as adding an attribute! No more accidentally passing arguments in the wrong order to methods - Strongly uses .NET 6's compile-time incremental source generators to generate the boilerplate required to use strongly-typed IDs.
Simply, install the required package add the [Strongly] attribute to a struct (in the Strongly
namespace):
using Strongly;
[Strongly] // <- Add this attribute to auto-generate the rest of the type
public partial struct FooId { }and the source generator magically generates the backing code when you save the file! Use Go to Definition to see the generated code:
Strongly requires requires the .NET Core SDK v6.0.100 or greater.
To use the the Strongly NuGet package, install the Strongly package into your project. Depending on which converters you implement, you may need one or more of the following additional packages
- System.Text.Json (optional, only required
if generating a System.Text
JsonConverter). Note that in .NET Core apps, you will likely already reference this project via transitive dependencies. - Newtonsoft.Json (optional, only required
if generating a Newtonsoft
JsonConverter). Note that in some ASP.NET Core apps, you will likely already reference this project via transitive dependencies. - Dapper (optional, only required if generating a type mapper)
- EF Core (optional, only required if generating an EF Core ValueConverter)
- Swagger Annotations (optional, only required if generating an Swagger Schema Filter
To install the packages, add the references to your csproj file, for example by running
dotnet add package Strongly This adds a <PackageReference> to your project. You can additionally mark the package as PrivateAssets="all"
and ExcludeAssets="runtime".
Setting
PrivateAssets="all"means any projects referencing this one will not also get a reference to the Strongly package. SettingExcludeAssets="runtime"ensures the Strongly.Attributes.dll file is not copied to your build output (it is not required at runtime).
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
</PropertyGroup>
<!-- Add the package -->
<PackageReference Include="Strongly" Version="1.0.0" PrivateAssets="all" ExcludeAssets="runtime"/>
<!-- -->
</Project>To create a strongly-typed ID, create a partial struct with the desired name, and decorate it with the [Strongly]
attribute, in the Strongly namespace:
using Strongly;
[Strongly] // Add this attribute to auto-generate the rest of the type
public partial struct FooId { }This generates the "default" strongly-typed ID using a Guid backing field, a custom TypeConverter, and a
custom JsonConverter based on System.Text.Json.
You can customise which converters to generate by using flags. For example, to generate a TypeConverter,
a Newtonsoft.Json, and an EF Core ValueConverter, use
using Strongly;
[Strongly(converters: StronglyConverter.TypeConverter | StronglyConverter.SystemTextJson | StronglyConverter.EfValueConverter)]
public partial struct SystemTextJsonConverterId { }The default strongly-typed ID uses a Guid backing field:
using Strongly;
[Strongly]
public partial struct FooId { }
var id = new FooId(Guid.NewGuid());You can choose a different type backing field, by passing a value of the StronglyBackingType enum in the constructor.
using Strongly;
[Strongly(backingType: StronglyBackingType.String)]
public partial struct FooId { }
var id = new FooId("my-id-value");Currently supported values are Guid (the default), int, long,decimal,BigInteger, MassTransit.NewId
and string.
If you wish to change the converters, backing types, or implementations used by default for all the [Strongly]
-decorated types in your project, you can use the assembly attribute [StronglyDefaults] to set all of these. For
example, the following sets the default converter to a whole project to [SystemTextJson], and changes the default
backing-type to an int
// Set the defaults for the project
[assembly:StronglyDefaults(
backingType: StronglyType.Int,
converters: StronglyConverter.SystemTextJson)]
[Strongly]
public partial struct OrderId { }
[Strongly]
public partial struct UserId { } This is equivalent to setting these values manually on all the IDs:
[Strongly(
backingType: StronglyType.Int,
converters: StronglyConverter.SystemTextJson)]
public partial struct OrderId { }
[Strongly(
backingType: StronglyType.Int,
converters: StronglyConverter.SystemTextJson)]
public partial struct UserId { }When you create a Strongly type with EF Converter, the type will have a nested ValueConverter class you can use on
your entity model definition
[Strongly(StronglyType.String, StronglyConverter.EfValueConverter)]
public partial struct PhoneNumber
{
}
public class MyDbContext : DbContext
{
protected override void OnModelCreating(ModelBuilder builder)
{
var customer = builder.Entity<Customer>();
customer.Property(x => x.Phone).HasConversion<PhoneNumber.EfValueConverter>();
}
}If you have lots of strongly type values you can use the package bellow to automatically set
the Strongly ValueConverter on all your entities
dotnet add package Strongly.EFCoreAfter installation you need to set it on yor DbContextOptionsBuilder
services
.AddDbContext<AppDbContext>(options => options
.UseStronglyTypeConverters()
/* ... */
)If you wish to use an ID in your Swagger models and want to have schema and model sample reflecting the value backing-field type you will need:
- Install Swagger Annotations
>=5.0.0 - Enable annotation in swagger gen with
services.AddSwaggerGen(c => c.EnableAnnotations()); - Use the converter flag
StronglyConverter.SwaggerSchemaFilteron the ID decorator. eg:[Strongly( backingType: StronglyType.Int, converters: StronglyConverter.SwaggerSchemaFilter | StronglyConverter.SystemTextJson)] public partial struct UserId { }
By default, the [Strongly] attributes referenced in your application are contained in an external dll. It is also
possible to embed the attributes directly in your project, so they appear in the dll when your project is built. If you
wish to do this, you must do two things:
- Define the MSBuild constant
STRONGLY_TYPED_EMBED_ATTRIBUTES. This ensures the attributes are embedded in your project - Add
compileto the list of excluded assets in your<PackageReference>element. This ensures the attributes in your project are referenced, instead of the Strongly.Attributes.dll library.
Your project file should look something like this:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
<!-- Define the MSBuild constant -->
<DefineConstants>STRONGLY_TYPED_EMBED_ATTRIBUTES</DefineConstants>
</PropertyGroup>
<!-- Add the package -->
<PackageReference Include="Strongly" Version="1.0.0"
PrivateAssets="all"
ExcludeAssets="compile;runtime"/>
<!-- ☝ Add compile to the list of excluded assets. -->
</Project>The [Strongly] and [StronglyDefaults] attributes are decorated with the [Conditional]
attribute, so their usage will not appear in the build output of your project.
If you use reflection at runtime on one of your IDs, you will not find [Strongly] in the list of custom attributes.
If you wish to preserve these attributes in the build output, you can define the STRONGLY_TYPED_USAGES MSBuild
variable. Note that this means your project will have a runtime-dependency on Strongly.Attributes.dll so you need to
ensure this is included in your build output.
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
<!-- Define the MSBuild constant to preserve usages -->
<DefineConstants>STRONGLY_TYPED_USAGES</DefineConstants>
</PropertyGroup>
<!-- Add the package -->
<PackageReference Include="Strongly" Version="1.0.0" PrivateAssets="all"/>
<!-- ☝ You must not exclude the runtime assets in this case -->
</Project>Andrew have written a blog-post series on strongly-typed IDs that explains the issues and rational behind this library. For a detailed view, I suggest starting there, but I provide a brief introduction here.
This library is designed to tackle a specific instance of primitive
obsession, whereby we use primitive
objects (Guid/string/int/long/decimal etc) to represent the IDs or values of
domain objects. The problem is that these
types are all
interchangeable - an order ID can be assigned to a product ID despite the fact that is likely nonsensical from the
domain point of
view. See here for a more concrete example.
By using strongly-typed values, we give each of then its own Type which wraps the underlying primitive value. This
ensures
you can only use the value where it makes sense: ProductIds can only be assigned to products, or you can only search
for
products using a ProductId, not an OrderId.
Unfortunately, taking this approach requires a lot of boilerplate and ceremony to make working with it manageable. This library abstracts all that away from you, by generating the boilerplate at build-time by using a Roslyn-powered code generator.
The exact code generated depends on the arguments you provide to the Strongly attribute. The code is generated to the
obj folder of the project, so you can use Go to Definition on your Id to see the exact code generated in each
case.
The Strongly NuGet package is a .NET Standard 2.0 package.
You must be using the .NET 6+ SDK (though you can compile for other target frameworks like .NET Core 2.1 and .NET Framework 4.8)
The structs you decorate with the Strongly attribute must be marked partial.
This project born as a fork of StronglyTypedId