Inject Dependencies into Validation Attribute using ASP.NET Core's WebAPI

Question

I'm building a Custom Validation Attribute in ASP.NET Core WebAPI. I need to access IDataProtector in my validator and another service I'm using to access the database. I've searched and wasn't ab;e to find any documentation for this. ActionFilters have the option of using ServiceFilter but there doesn't seem to be any option for Validation Attribute. Any ideas?

Answer 1

Use the GetService() method of the ValidationContext to get your database. i.e.

protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
  MyDbContext db = (MyDbContext) validationContext.GetService(typeof(MyDbContext));
  //...
}

Answer 2

You can override IsValid method and use validationContext to resolve dependency:

protected override ValidationResult IsValid(object value, ValidationContext validationContext)  
{
    var service = (IExternalService) validationContext.GetService(typeof(IExternalService));
    // use service
}