我想输出两个不同的视图(一个作为字符串，将作为电子邮件发送)，另一个是显示给用户的页面。
这在ASP中可能吗?NET MVC beta版?
我试过很多例子:
1. 在ASP。NET MVC Beta版
如果我使用这个例子，我会收到“HTTP后不能重定向”
报头已发送。”
2. MVC框架:捕获视图的输出
如果我使用这个，我似乎无法做一个重定向toaction，因为它
试图呈现一个可能不存在的视图。如果我返回视图
完全是一团糟，看起来一点都不对。
有人对我提出的这些问题有什么想法/解决方案吗?或者有什么更好的建议吗?
很多谢谢!
下面是一个例子。我要做的是创建GetViewForEmail方法:
public ActionResult OrderResult(string ref)
{
//Get the order
Order order = OrderService.GetOrder(ref);
//The email helper would do the meat and veg by getting the view as a string
//Pass the control name (OrderResultEmail) and the model (order)
string emailView = GetViewForEmail("OrderResultEmail", order);
//Email the order out
EmailHelper(order, emailView);
return View("OrderResult", order);
}
接受蒂姆·斯科特的回答(我做了一些修改和格式化):
public virtual string RenderViewToString(
ControllerContext controllerContext,
string viewPath,
string masterPath,
ViewDataDictionary viewData,
TempDataDictionary tempData)
{
Stream filter = null;
ViewPage viewPage = new ViewPage();
//Right, create our view
viewPage.ViewContext = new ViewContext(controllerContext, new WebFormView(viewPath, masterPath), viewData, tempData);
//Get the response context, flush it and get the response filter.
var response = viewPage.ViewContext.HttpContext.Response;
response.Flush();
var oldFilter = response.Filter;
try
{
//Put a new filter into the response
filter = new MemoryStream();
response.Filter = filter;
//Now render the view into the memorystream and flush the response
viewPage.ViewContext.View.Render(viewPage.ViewContext, viewPage.ViewContext.HttpContext.Response.Output);
response.Flush();
//Now read the rendered view.
filter.Position = 0;
var reader = new StreamReader(filter, response.ContentEncoding);
return reader.ReadToEnd();
}
finally
{
//Clean up.
if (filter != null)
{
filter.Dispose();
}
//Now replace the response filter
response.Filter = oldFilter;
}
}
示例使用
假设控制器通过Site调用订单确认电子邮件。主人的位置。
string myString = RenderViewToString(this.ControllerContext, "~/Views/Order/OrderResultEmail.aspx", "~/Views/Shared/Site.Master", this.ViewData, this.TempData);
asp.net CORE的额外提示:
接口:
public interface IViewRenderer
{
Task<string> RenderAsync<TModel>(Controller controller, string name, TModel model);
}
实现:
public class ViewRenderer : IViewRenderer
{
private readonly IRazorViewEngine viewEngine;
public ViewRenderer(IRazorViewEngine viewEngine) => this.viewEngine = viewEngine;
public async Task<string> RenderAsync<TModel>(Controller controller, string name, TModel model)
{
ViewEngineResult viewEngineResult = this.viewEngine.FindView(controller.ControllerContext, name, false);
if (!viewEngineResult.Success)
{
throw new InvalidOperationException(string.Format("Could not find view: {0}", name));
}
IView view = viewEngineResult.View;
controller.ViewData.Model = model;
await using var writer = new StringWriter();
var viewContext = new ViewContext(
controller.ControllerContext,
view,
controller.ViewData,
controller.TempData,
writer,
new HtmlHelperOptions());
await view.RenderAsync(viewContext);
return writer.ToString();
}
}
在Startup.cs中注册
...
services.AddSingleton<IViewRenderer, ViewRenderer>();
...
在控制器中的使用:
public MyController: Controller
{
private readonly IViewRenderer renderer;
public MyController(IViewRendere renderer) => this.renderer = renderer;
public async Task<IActionResult> MyViewTest
{
var view = await this.renderer.RenderAsync(this, "MyView", model);
return new OkObjectResult(view);
}
}
我发现了一个新的解决方案，可以将视图呈现为字符串，而不必与当前HttpContext的Response流(它不允许您更改响应的ContentType或其他报头)混淆。
基本上，你所要做的就是为视图创建一个伪HttpContext来渲染它自己:
/// <summary>Renders a view to string.</summary>
public static string RenderViewToString(this Controller controller,
string viewName, object viewData) {
//Create memory writer
var sb = new StringBuilder();
var memWriter = new StringWriter(sb);
//Create fake http context to render the view
var fakeResponse = new HttpResponse(memWriter);
var fakeContext = new HttpContext(HttpContext.Current.Request, fakeResponse);
var fakeControllerContext = new ControllerContext(
new HttpContextWrapper(fakeContext),
controller.ControllerContext.RouteData,
controller.ControllerContext.Controller);
var oldContext = HttpContext.Current;
HttpContext.Current = fakeContext;
//Use HtmlHelper to render partial view to fake context
var html = new HtmlHelper(new ViewContext(fakeControllerContext,
new FakeView(), new ViewDataDictionary(), new TempDataDictionary()),
new ViewPage());
html.RenderPartial(viewName, viewData);
//Restore context
HttpContext.Current = oldContext;
//Flush memory and return output
memWriter.Flush();
return sb.ToString();
}
/// <summary>Fake IView implementation used to instantiate an HtmlHelper.</summary>
public class FakeView : IView {
#region IView Members
public void Render(ViewContext viewContext, System.IO.TextWriter writer) {
throw new NotImplementedException();
}
#endregion
}
这适用于ASP。NET MVC 1.0，以及ContentResult, JsonResult等(改变原始HttpResponse上的报头不会抛出“发送HTTP报头后服务器无法设置内容类型”异常)。
更新:在ASP。NET MVC 2.0 RC，代码有一点变化，因为我们必须传入用于将视图写入ViewContext的StringWriter:
//...
//Use HtmlHelper to render partial view to fake context
var html = new HtmlHelper(
new ViewContext(fakeControllerContext, new FakeView(),
new ViewDataDictionary(), new TempDataDictionary(), memWriter),
new ViewPage());
html.RenderPartial(viewName, viewData);
//...
为了在服务层中呈现一个字符串的视图，而不需要传递ControllerContext, Rick Strahl在http://www.codemag.com/Article/1312081有一篇很好的文章，它创建了一个通用控制器。代码摘要如下:
// Some Static Class
public static string RenderViewToString(ControllerContext context, string viewPath, object model = null, bool partial = false)
{
// first find the ViewEngine for this view
ViewEngineResult viewEngineResult = null;
if (partial)
viewEngineResult = ViewEngines.Engines.FindPartialView(context, viewPath);
else
viewEngineResult = ViewEngines.Engines.FindView(context, viewPath, null);
if (viewEngineResult == null)
throw new FileNotFoundException("View cannot be found.");
// get the view and attach the model to view data
var view = viewEngineResult.View;
context.Controller.ViewData.Model = model;
string result = null;
using (var sw = new StringWriter())
{
var ctx = new ViewContext(context, view, context.Controller.ViewData, context.Controller.TempData, sw);
view.Render(ctx, sw);
result = sw.ToString();
}
return result;
}
// In the Service Class
public class GenericController : Controller
{ }
public static T CreateController<T>(RouteData routeData = null) where T : Controller, new()
{
// create a disconnected controller instance
T controller = new T();
// get context wrapper from HttpContext if available
HttpContextBase wrapper;
if (System.Web.HttpContext.Current != null)
wrapper = new HttpContextWrapper(System.Web.HttpContext.Current);
else
throw new InvalidOperationException("Cannot create Controller Context if no active HttpContext instance is available.");
if (routeData == null)
routeData = new RouteData();
// add the controller routing if not existing
if (!routeData.Values.ContainsKey("controller") &&
!routeData.Values.ContainsKey("Controller"))
routeData.Values.Add("controller", controller.GetType().Name.ToLower().Replace("controller", ""));
controller.ControllerContext = new ControllerContext(wrapper, routeData, controller);
return controller;
}
然后在Service类中呈现View:
var stringView = RenderViewToString(CreateController<GenericController>().ControllerContext, "~/Path/To/View/Location/_viewName.cshtml", theViewModel, true);
这个答案不在我的路上。这最初来自https://stackoverflow.com/a/2759898/2318354，但在这里我已经展示了如何使用它与“静态”关键字，使它通用于所有控制器。
为此，你必须在类文件中创建静态类。(假设你的类文件名是Utils.cs)
这个例子是剃须刀。
Utils.cs
public static class RazorViewToString
{
public static string RenderRazorViewToString(this Controller controller, string viewName, object model)
{
controller.ViewData.Model = model;
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName);
var viewContext = new ViewContext(controller.ControllerContext, viewResult.View, controller.ViewData, controller.TempData, sw);
viewResult.View.Render(viewContext, sw);
viewResult.ViewEngine.ReleaseView(controller.ControllerContext, viewResult.View);
return sw.GetStringBuilder().ToString();
}
}
}
现在你可以从你的控制器调用这个类，通过在你的控制器文件中添加命名空间，通过将“this”作为参数传递给控制器，如下所示。
string result = RazorViewToString.RenderRazorViewToString(this ,"ViewName", model);
正如@Sergey给出的建议，这个扩展方法也可以从控制器调用，如下所示
string result = this.RenderRazorViewToString("ViewName", model);
我希望这将有助于您使代码干净整洁。
asp.net CORE的额外提示:
接口:
public interface IViewRenderer
{
Task<string> RenderAsync<TModel>(Controller controller, string name, TModel model);
}
实现:
public class ViewRenderer : IViewRenderer
{
private readonly IRazorViewEngine viewEngine;
public ViewRenderer(IRazorViewEngine viewEngine) => this.viewEngine = viewEngine;
public async Task<string> RenderAsync<TModel>(Controller controller, string name, TModel model)
{
ViewEngineResult viewEngineResult = this.viewEngine.FindView(controller.ControllerContext, name, false);
if (!viewEngineResult.Success)
{
throw new InvalidOperationException(string.Format("Could not find view: {0}", name));
}
IView view = viewEngineResult.View;
controller.ViewData.Model = model;
await using var writer = new StringWriter();
var viewContext = new ViewContext(
controller.ControllerContext,
view,
controller.ViewData,
controller.TempData,
writer,
new HtmlHelperOptions());
await view.RenderAsync(viewContext);
return writer.ToString();
}
}
在Startup.cs中注册
...
services.AddSingleton<IViewRenderer, ViewRenderer>();
...
在控制器中的使用:
public MyController: Controller
{
private readonly IViewRenderer renderer;
public MyController(IViewRendere renderer) => this.renderer = renderer;
public async Task<IActionResult> MyViewTest
{
var view = await this.renderer.RenderAsync(this, "MyView", model);
return new OkObjectResult(view);
}
}
