public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
if (ProviderType == null)
{
throw new ArgumentNullException(nameof(ProviderType));
}
if (!typeof(ITagHelpersProvider).IsAssignableFrom(ProviderType))
{
throw new ArgumentException(nameof(ProviderType));
}
var instance = ViewContext.HttpContext.RequestServices.GetService(ProviderType) as ITagHelpersProvider;
if (instance == null)
{
throw new ArgumentException(nameof(ProviderType));
}
string childContent;
output.TagName = string.Empty;
using (var providerContext = new TagHelpersProviderContext(instance, ViewContext))
{
childContent = output.Content.IsModified ? output.Content.GetContent() :
(await output.GetChildContentAsync()).GetContent();
}
output.Content.SetHtmlContent(childContent);
}
public TagHelpersProviderContext(ITagHelpersProvider provider, ViewContext context)
{
this.provider = provider;
this.context = context;
oldProviderContext = context.ViewData[field] as TagHelpersProviderContext ??
new TagHelpersProviderContext(context.HttpContext.RequestServices.GetService <DefaultTagHelpersProvider>());
if (oldProviderContext == provider)
{
return;
}
oldProviderContext.provider.UnPrepareViewContext(context);
context.ViewData[field] = this;
context.ClientValidationEnabled = provider.RequireUnobtrusiveValidation;
provider.PrepareViewContext(context);
}
