Description
Add new methos to and existing class
In ASP.NET Core when I'm going to build my own validation provider, I have to register it to work with the built-in on that is provided by ASP.NET Core framework, I have to implement two interfaces:
- IModelValidatorProvider
- IModelValidator
The IModelValidatorProvider has a method named CreateValidators and accept on parameter of type ModelValidatorProviderContext object.
In this method you may need to resolve some dependency object and to do that you have to inject the IServiceCollection interface and us it like so:
var validator = _serviceCollection.BuildServiceProvider()
.GetService(validatorType);Instead of doing that my suggestion here is to add a new method to this class (ModelValidatorProviderContext) named GetService and should accept one parameter of type Type object
namespace Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
public class ModelValidatorProviderContext
{
public ModelValidatorProviderContext(ModelMetadata modelMetadata, IList<ValidatorItem> items)
{
ModelMetadata = modelMetadata;
Results = items;
}
public ModelMetadata ModelMetadata { get; set; }
public IReadOnlyList<object> ValidatorMetadata => ModelMetadata.ValidatorMetadata;
public IList<ValidatorItem> Results { get; }
// this is the new method
object? IServiceProvider GetService(type type);
}Here is the new method:
object? IServiceProvider GetService(type type);And now here I can user the GetService method without needing to inject IServiceCollection interface to the object constructor:
var validatorType = typeof(IValidator<>).MakeGenericType(
context.ModelMetadata.ModelType);
var object = context.GetService(validatorType)Usage Examples
Here is my complete custom validator provider object:
public class ModelValidatorProvider : IModelValidatorProvider
{
// now no need for constructor at al here
public void CreateValidators(ModelValidatorProviderContext context)
{
var validatorType = typeof(IValidator<>).MakeGenericType(
context.ModelMetadata.ModelType);
// here is the usage of the new method
var validator = context.GetService(validatorType)
if (validator != null)
{
var simpleValidatorType = typeof(ModelValidator<>).MakeGenericType(context.ModelMetadata.ModelType);
var simpleValidator = (IModelValidator?)Activator.CreateInstance(simpleValidatorType, validator);
context.Results.Add(new ValidatorItem
{
IsReusable = true,
Validator = simpleValidator
});
}
}