I am building an ASP.NET Core 2 MVC application. A lot of the time I need to make use of dependencies to validate user input. I want my validation methods to be unit testable, and I want to be able to inject mocked dependencies into them. This is something I have previously done in MVC5 to great success but cannot work out the ASP.NET Core 2 equivalent.
This is how I would do it in MVC5:
// the view model to be validated
public class MyViewModel {
public string Username { get; set; }
}
// the model validator that will have dependencies injected into it
public class MyViewModelValidator : ModelValidator
{
private IUserService users;
private MyViewModel model;
public MyViewModelValidator(ModelMetadata metadata, ControllerContext controllerContext, IUserService users)
: base(metadata, controllerContext)
{
this.users = users;
this.model = base.Metadata.Model as MyViewModel;
}
public override IEnumerable<ModelValidationResult> Validate(object container)
{
List<ModelValidationResult> errors = new List<ModelValidationResult>();
if (this.users.CheckExists(this.model.Username))
{
errors.Add(new ModelValidationResult() { MemberName = nameof(MyViewModel.Username), Message = "Username is not available" });
}
return errors;
}
}
// this class works out which validator is required for a given model and
// injects the appropriate dependencies that is resolves using unity in my
// in my case
public class ViewModelValidatorProvider : ModelValidatorProvider
{
private IUnityContainer container;
public ViewModelValidatorProvider() => this.container = DependencyResolver.Current.GetService<IUnityContainer>();
public override IEnumerable<ModelValidator> GetValidators(ModelMetadata metadata, ControllerContext context)
{
if (metadata.ModelType == typeof(MyViewModel))
yield return new MyViewModelValidator(metadata, context, this.container.Resolve<IUserService>());
}
}
// the provider is hooked up in the app start in Global.asax.cs file
public class MvcApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
ModelValidatorProviders.Providers.Add(new ViewModelValidatorProvider());
}
}
Now I can just create an instance of the validator with mocked dependencies and away I go! Sadly ASP.NET Core 2 doesn't have the ModelValidator
class and everything I have found so far seems to want to inject dependencies via the controller or to resolve them with in an IValidatableObject
s Validate()
function.
Is it possible to do this in MVC Core?