FSharp.TypeConverter

Getting started

$ dotnet add package FSharp.TypeConverter

💡 You can check a complete sample HERE

How to use

Option<'T>

For Option<'T> you will need to call TypeDescriptor.addDefaultOptionTypes(), this will add type-converters for almost all BLC and common types.

If you need to use any other optional type you can add it manually with TypeDescriptor.addOption<YourType>

Discriminated Unions

This library will deal with only two types of union types:

Single Case Unions (ex: type Email = Email of string)
Fieldless Unions (ex: type Light = On | Off)

To add definitions for your type just call TypeDescriptor functions at the very beginning of your program:

TypeDescriptor.addUnion<Email>
TypeDescriptor.addUnion<Light>

💡: This also adds the Option<T> handler for the registered union type

If you have a lot of types you can scan and load all valid union types using TypeDescriptor.addUnionTypesInAssemblyContaining<TypeOnAssembly>

Example

Using for ASP.NET Core Options Pattern

appsettings.json

{
  "Person": {
    "FirstName": "Jonny",
    "LastName": "Cage",
    "Email": "fsharp@dotnet.com",
    "Age": 35,
    "Status": "Enabled",
    "WebSite": "https://fsharpforfunandprofit.com"
  },
  "PersonEmpty": {
    "FirstName": "Goro",
    "Status": "Disabled",
    "Email": "prince@shokan.com",
    "LastName": null
  }
}

Program.fs

open System.ComponentModel

// Single case types
type Email = Email of string
type Natural = Natural of int
// Fieldless union
type Status = Enabled | Disabled

// Option model
[<CLIMutable>]
type PersonSettings =
    { FirstName: string
      LastName: string option
      Email: Email
      Age: Natural option
      Status: Status
      WebSite: Uri option }

// register option for BCL and common types
TypeDescriptor.addDefaultOptionTypes ()

// register all single case union types and empty unions on the assembly
TypeDescriptor.addUnionTypesInAssemblyContaining<PersonSettings>

// alternatively you can add one by one with
// TypeDescriptor.addUnion<Email>
// TypeDescriptor.addUnion<Natural>

let builder = WebApplication.CreateBuilder Array.empty

builder.Services
    .AddOptions<PersonSettings>()
    .BindConfiguration("Person")
    .ValidateOnStart()
|> ignore

let app = builder.Build()

// Options from dependency injection
let person = app.Services.GetRequiredService<IOptions<PersonSettings>>()
printfn $"Complete %A{person.Value}"

// Getting direct from the IConfiguration
let configuration = app.Services.GetRequiredService<IConfiguration>()
let emptyPerson = configuration.GetSection("PersonEmpty").Get<PersonSettings>()
printfn $"Missing %A{emptyPerson}"

Output

{ FirstName = "Jonny"
  LastName = Some "Cage"
  Email = Email "fsharp@dotnet.com"
  Age = Some (Natural 35)
  Status = Enabled
  WebSite = Some https://fsharpforfunandprofit.com/ }
  
{ FirstName = "Goro"
  LastName = None
  Email = Email "prince@shokan.com"
  Age = None
  Status = Disabled