/// <summary>
/// If the check returns <c>true</c>, <see cref="ValidationException"/>
/// is emitted as an error with the status code 400 (Bad Request).
/// Otherwise the given value is emitted.
/// </summary>
/// <typeparam name="TSource">The type of the value.</typeparam>
/// <param name="observable">The parent observable.</param>
/// <param name="modelState">
/// The <see cref="T:Microsoft.AspNetCore.Mvc.ModelBinding.ModelStateDictionary" /> that
/// contains the state of the model and of model-binding validation.
/// </param>
/// <returns>An instance of <see cref="IProviderObservable{TSource}"/>.</returns>
public static IProviderObservable<TSource> BadRequestWhenModelStateIsInvalid<TSource>(
this IProviderObservable<TSource> observable, ModelStateDictionary modelState)
{
var nameResolver = new Lazy<IJsonPropertyNameResolver>(
() => observable.ServiceProvider.GetService<IJsonPropertyNameResolver>());
return observable.BadRequestWhen(
() => !modelState.IsValid,
s => modelState.ToDictionary(
m => nameResolver.Value.Resolve(m.Key),
m => m.Value.Errors));
}
