asp.net core mvc html action code example
Example: how to call html.action in asp.net core
using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Html;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Controllers;
using Microsoft.AspNetCore.Mvc.Internal;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Routing;
namespace Microsoft.AspNetCore.Mvc.Rendering {
public static class HtmlHelperViewExtensions
{
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, object parameters = null)
{
var controller = (string)helper.ViewContext.RouteData.Values["controller"];
return RenderAction(helper, action, controller, parameters);
}
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, object parameters = null)
{
var area = (string)helper.ViewContext.RouteData.Values["area"];
return RenderAction(helper, action, controller, area, parameters);
}
public static IHtmlContent RenderAction(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
if (action == null)
throw new ArgumentNullException("action");
if (controller == null)
throw new ArgumentNullException("controller");
if (area == null)
throw new ArgumentNullException("area");
var task = RenderActionAsync(helper, action, controller, area, parameters);
return task.Result;
}
private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null)
{
// fetching required services for invocation
var currentHttpContext = helper.ViewContext?.HttpContext;
var httpContextFactory = GetServiceOrFail<IHttpContextFactory>(currentHttpContext);
var actionInvokerFactory = GetServiceOrFail<IActionInvokerFactory>(currentHttpContext);
var actionSelector = GetServiceOrFail<IActionSelectorDecisionTreeProvider>(currentHttpContext);
// creating new action invocation context
var routeData = new RouteData();
var routeParams = new RouteValueDictionary(parameters ?? new { });
var routeValues = new RouteValueDictionary(new { area = area, controller = controller, action = action });
var newHttpContext = httpContextFactory.Create(currentHttpContext.Features);
newHttpContext.Response.Body = new MemoryStream();
foreach (var router in helper.ViewContext.RouteData.Routers)
routeData.PushState(router, null, null);
routeData.PushState(null, routeValues, null);
routeData.PushState(null, routeParams, null);
var actionDescriptor = actionSelector.DecisionTree.Select(routeValues).First();
var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor);
// invoke action and retreive the response body
var invoker = actionInvokerFactory.CreateInvoker(actionContext);
string content = null;
await invoker.InvokeAsync().ContinueWith(task => {
if (task.IsFaulted)
{
content = task.Exception.Message;
}
else if (task.IsCompleted)
{
newHttpContext.Response.Body.Position = 0;
using (var reader = new StreamReader(newHttpContext.Response.Body))
content = reader.ReadToEnd();
}
});
return new HtmlString(content);
}
private static TService GetServiceOrFail<TService>(HttpContext httpContext)
{
if (httpContext == null)
throw new ArgumentNullException(nameof(httpContext));
var service = httpContext.RequestServices.GetService(typeof(TService));
if (service == null)
throw new InvalidOperationException($"Could not locate service: {nameof(TService)}");
return (TService)service;
}
}
}