MVC4: How to delete view render cache? - asp.net

Im using Virtual Path Provider to store my view in database. The problem i have is that whenever i change the view code from my database, my rendering code always produces the view that is saved when the application started. So the problem i have now is that i have to keep restarting my application in order to change my view. Here is my rendering code:
public static string RenderRazorViewToString(string viewToRender, object model, string controllerName, string loadAction, HttpContextBase httpContext)
{
string view = "";
ViewDataDictionary ViewData = new ViewDataDictionary(model);
Type controllerType = Type.GetType("CMS.Controllers." + controllerName + "Controller");
object controller = Activator.CreateInstance(controllerType);
RouteData rd = new System.Web.Routing.RouteData();
rd.Values.Add("controller", controllerName);
((ControllerBase)(controller)).ControllerContext = new ControllerContext(httpContext, rd, (ControllerBase)controller);
ControllerContext cc = ((ControllerBase)(controller)).ControllerContext;
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(cc, viewToRender);
var viewContext = new ViewContext(cc, viewResult.View, ViewData, cc.Controller.TempData, sw);
viewResult.View.Render(viewContext, sw);
viewResult.ViewEngine.ReleaseView(cc, viewResult.View);
view = sw.GetStringBuilder().ToString();
}
return view;
}
the ViewResult.View.Render(viewContext, sw) always renders the cached view. So how to delete the cache whenever i edited the view code?

Related

asp.net mvc 5 action filter that renders view as json

In my asp.net mvc 5 application is it possible to write an action filter that will intercept an ActionResult and return a JsonResult containing the rendered view as an html string and the model as json?
Consider this pseudo code:
JSON(new { html = ViewAsHTMLString, model = this.ViewsViewModel })
I use a simple ActionResult method like this in my application:
return Json(new
{
result = "fail",
html = Extensions.RenderViewToString(ControllerContext, "_Partial_CreatePageContainer", model),
errors = "This page already exists."
});
I then created 2 extension methods to handle the view rendering:
public static string RenderViewToString(ControllerContext context, string viewName, object model)
{
if (string.IsNullOrEmpty(viewName))
viewName = context.RouteData.GetRequiredString("action");
var viewData = new ViewDataDictionary(model);
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(context, viewName);
var viewContext = new ViewContext(context, viewResult.View, viewData, new TempDataDictionary(), sw);
viewResult.View.Render(viewContext, sw);
return sw.GetStringBuilder().ToString();
}
}
public static string RenderViewToString(ControllerContext context, string viewName)
{
if (string.IsNullOrEmpty(viewName))
viewName = context.RouteData.GetRequiredString("action");
var viewData = new ViewDataDictionary();
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(context, viewName);
var viewContext = new ViewContext(context, viewResult.View, viewData, new TempDataDictionary(), sw);
viewResult.View.Render(viewContext, sw);
return sw.GetStringBuilder().ToString();
}
}

How to get ViewResult as a string? [duplicate]

I want to output two different views (one as a string that will be sent as an email), and the other the page displayed to a user.
Is this possible in ASP.NET MVC beta?
I've tried multiple examples:
1. RenderPartial to String in ASP.NET MVC Beta
If I use this example, I receive the "Cannot redirect after HTTP
headers have been sent.".
2. MVC Framework: Capturing the output of a view
If I use this, I seem to be unable to do a redirectToAction, as it
tries to render a view that may not exist. If I do return the view, it
is completely messed up and doesn't look right at all.
Does anyone have any ideas/solutions to these issues i have, or have any suggestions for better ones?
Many thanks!
Below is an example. What I'm trying to do is create the GetViewForEmail method:
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);
}
Accepted answer from Tim Scott (changed and formatted a little by me):
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;
}
}
Example usage
Assuming a call from the controller to get the order confirmation email, passing the Site.Master location.
string myString = RenderViewToString(this.ControllerContext, "~/Views/Order/OrderResultEmail.aspx", "~/Views/Shared/Site.Master", this.ViewData, this.TempData);
Here's what I came up with, and it's working for me. I added the following method(s) to my controller base class. (You can always make these static methods somewhere else that accept a controller as a parameter I suppose)
MVC2 .ascx style
protected string RenderViewToString<T>(string viewPath, T model) {
ViewData.Model = model;
using (var writer = new StringWriter()) {
var view = new WebFormView(ControllerContext, viewPath);
var vdd = new ViewDataDictionary<T>(model);
var viewCxt = new ViewContext(ControllerContext, view, vdd,
new TempDataDictionary(), writer);
viewCxt.View.Render(viewCxt, writer);
return writer.ToString();
}
}
Razor .cshtml style
public string RenderRazorViewToString(string viewName, object model)
{
ViewData.Model = model;
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(ControllerContext,
viewName);
var viewContext = new ViewContext(ControllerContext, viewResult.View,
ViewData, TempData, sw);
viewResult.View.Render(viewContext, sw);
viewResult.ViewEngine.ReleaseView(ControllerContext, viewResult.View);
return sw.GetStringBuilder().ToString();
}
}
Edit: added Razor code.
This answer is not on my way . This is originally from https://stackoverflow.com/a/2759898/2318354 but here I have show the way to use it with "Static" Keyword to make it common for all Controllers .
For that you have to make static class in class file . (Suppose your Class File Name is Utils.cs )
This example is For Razor.
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();
}
}
}
Now you can call this class from your controller by adding NameSpace in your Controller File as following way by passing "this" as parameter to Controller.
string result = RazorViewToString.RenderRazorViewToString(this ,"ViewName", model);
As suggestion given by #Sergey this extension method can also call from cotroller as given below
string result = this.RenderRazorViewToString("ViewName", model);
I hope this will be useful to you make code clean and neat.
This works for me:
public virtual string RenderView(ViewContext viewContext)
{
var response = viewContext.HttpContext.Response;
response.Flush();
var oldFilter = response.Filter;
Stream filter = null;
try
{
filter = new MemoryStream();
response.Filter = filter;
viewContext.View.Render(viewContext, viewContext.HttpContext.Response.Output);
response.Flush();
filter.Position = 0;
var reader = new StreamReader(filter, response.ContentEncoding);
return reader.ReadToEnd();
}
finally
{
if (filter != null)
{
filter.Dispose();
}
response.Filter = oldFilter;
}
}
I found a new solution that renders a view to string without having to mess with the Response stream of the current HttpContext (which doesn't allow you to change the response's ContentType or other headers).
Basically, all you do is create a fake HttpContext for the view to render itself:
/// <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
}
This works on ASP.NET MVC 1.0, together with ContentResult, JsonResult, etc. (changing Headers on the original HttpResponse doesn't throw the "Server cannot set content type after HTTP headers have been sent" exception).
Update: in ASP.NET MVC 2.0 RC, the code changes a bit because we have to pass in the StringWriter used to write the view into the ViewContext:
//...
//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);
//...
This article describes how to render a View to a string in different scenarios:
MVC Controller calling another of its own ActionMethods
MVC Controller calling an ActionMethod of another MVC Controller
WebAPI Controller calling an ActionMethod of an MVC Controller
The solution/code is provided as a class called ViewRenderer. It is part of Rick Stahl's WestwindToolkit at GitHub.
Usage (3. - WebAPI example):
string html = ViewRenderer.RenderView("~/Areas/ReportDetail/Views/ReportDetail/Index.cshtml", ReportVM.Create(id));
If you want to forgo MVC entirely, thereby avoiding all the HttpContext mess...
using RazorEngine;
using RazorEngine.Templating; // For extension methods.
string razorText = System.IO.File.ReadAllText(razorTemplateFileLocation);
string emailBody = Engine.Razor.RunCompile(razorText, "templateKey", typeof(Model), model);
This uses the awesome open source Razor Engine here:
https://github.com/Antaris/RazorEngine
Additional tip for ASP NET CORE:
Interface:
public interface IViewRenderer
{
Task<string> RenderAsync<TModel>(Controller controller, string name, TModel model);
}
Implementation:
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();
}
}
Registration in Startup.cs
...
services.AddSingleton<IViewRenderer, ViewRenderer>();
...
And usage in controller:
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);
}
}
To render a view to a string in the Service Layer without having to pass ControllerContext around, there is a good Rick Strahl article here http://www.codemag.com/Article/1312081 that creates a generic controller. Code summary below:
// 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;
}
Then to render the View in the Service class:
var stringView = RenderViewToString(CreateController<GenericController>().ControllerContext, "~/Path/To/View/Location/_viewName.cshtml", theViewModel, true);
you can get the view in string using this way
protected string RenderPartialViewToString(string viewName, object model)
{
if (string.IsNullOrEmpty(viewName))
viewName = ControllerContext.RouteData.GetRequiredString("action");
if (model != null)
ViewData.Model = model;
using (StringWriter sw = new StringWriter())
{
ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, viewName);
ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
viewResult.View.Render(viewContext, sw);
return sw.GetStringBuilder().ToString();
}
}
We can call this method in two way
string strView = RenderPartialViewToString("~/Views/Shared/_Header.cshtml", null)
OR
var model = new Person()
string strView = RenderPartialViewToString("~/Views/Shared/_Header.cshtml", model)
I am using MVC 1.0 RTM and none of the above solutions worked for me. But this one did:
Public Function RenderView(ByVal viewContext As ViewContext) As String
Dim html As String = ""
Dim response As HttpResponse = HttpContext.Current.Response
Using tempWriter As New System.IO.StringWriter()
Dim privateMethod As MethodInfo = response.GetType().GetMethod("SwitchWriter", BindingFlags.NonPublic Or BindingFlags.Instance)
Dim currentWriter As Object = privateMethod.Invoke(response, BindingFlags.NonPublic Or BindingFlags.Instance Or BindingFlags.InvokeMethod, Nothing, New Object() {tempWriter}, Nothing)
Try
viewContext.View.Render(viewContext, Nothing)
html = tempWriter.ToString()
Finally
privateMethod.Invoke(response, BindingFlags.NonPublic Or BindingFlags.Instance Or BindingFlags.InvokeMethod, Nothing, New Object() {currentWriter}, Nothing)
End Try
End Using
Return html
End Function
I saw an implementation for MVC 3 and Razor from another website, it worked for me:
public static string RazorRender(Controller context, string DefaultAction)
{
string Cache = string.Empty;
System.Text.StringBuilder sb = new System.Text.StringBuilder();
System.IO.TextWriter tw = new System.IO.StringWriter(sb);
RazorView view_ = new RazorView(context.ControllerContext, DefaultAction, null, false, null);
view_.Render(new ViewContext(context.ControllerContext, view_, new ViewDataDictionary(), new TempDataDictionary(), tw), tw);
Cache = sb.ToString();
return Cache;
}
public static string RenderRazorViewToString(string viewName, object model)
{
ViewData.Model = model;
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, viewName);
var viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
viewResult.View.Render(viewContext, sw);
return sw.GetStringBuilder().ToString();
}
}
public static class HtmlHelperExtensions
{
public static string RenderPartialToString(ControllerContext context, string partialViewName, ViewDataDictionary viewData, TempDataDictionary tempData)
{
ViewEngineResult result = ViewEngines.Engines.FindPartialView(context, partialViewName);
if (result.View != null)
{
StringBuilder sb = new StringBuilder();
using (StringWriter sw = new StringWriter(sb))
{
using (HtmlTextWriter output = new HtmlTextWriter(sw))
{
ViewContext viewContext = new ViewContext(context, result.View, viewData, tempData, output);
result.View.Render(viewContext, output);
}
}
return sb.ToString();
}
return String.Empty;
}
}
More on Razor render- MVC3 View Render to String
Quick tip
For a strongly typed Model just add it to the ViewData.Model property before passing to RenderViewToString. e.g
this.ViewData.Model = new OrderResultEmailViewModel(order);
string myString = RenderViewToString(this.ControllerContext, "~/Views/Order/OrderResultEmail.aspx", "~/Views/Shared/Site.Master", this.ViewData, this.TempData);
To repeat from a more unknown question, take a look at MvcIntegrationTestFramework.
It makes saves you writing your own helpers to stream result and is proven to work well enough. I'd assume this would be in a test project and as a bonus you would have the other testing capabilities once you've got this setup. Main bother would probably be sorting out the dependency chain.
private static readonly string mvcAppPath =
Path.GetFullPath(AppDomain.CurrentDomain.BaseDirectory
+ "\\..\\..\\..\\MyMvcApplication");
private readonly AppHost appHost = new AppHost(mvcAppPath);
[Test]
public void Root_Url_Renders_Index_View()
{
appHost.SimulateBrowsingSession(browsingSession => {
RequestResult result = browsingSession.ProcessRequest("");
Assert.IsTrue(result.ResponseText.Contains("<!DOCTYPE html"));
});
}
Here is a class I wrote to do this for ASP.NETCore RC2. I use it so I can generate html email using Razor.
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Routing;
using System.IO;
using System.Threading.Tasks;
namespace cloudscribe.Web.Common.Razor
{
/// <summary>
/// the goal of this class is to provide an easy way to produce an html string using
/// Razor templates and models, for use in generating html email.
/// </summary>
public class ViewRenderer
{
public ViewRenderer(
ICompositeViewEngine viewEngine,
ITempDataProvider tempDataProvider,
IHttpContextAccessor contextAccesor)
{
this.viewEngine = viewEngine;
this.tempDataProvider = tempDataProvider;
this.contextAccesor = contextAccesor;
}
private ICompositeViewEngine viewEngine;
private ITempDataProvider tempDataProvider;
private IHttpContextAccessor contextAccesor;
public async Task<string> RenderViewAsString<TModel>(string viewName, TModel model)
{
var viewData = new ViewDataDictionary<TModel>(
metadataProvider: new EmptyModelMetadataProvider(),
modelState: new ModelStateDictionary())
{
Model = model
};
var actionContext = new ActionContext(contextAccesor.HttpContext, new RouteData(), new ActionDescriptor());
var tempData = new TempDataDictionary(contextAccesor.HttpContext, tempDataProvider);
using (StringWriter output = new StringWriter())
{
ViewEngineResult viewResult = viewEngine.FindView(actionContext, viewName, true);
ViewContext viewContext = new ViewContext(
actionContext,
viewResult.View,
viewData,
tempData,
output,
new HtmlHelperOptions()
);
await viewResult.View.RenderAsync(viewContext);
return output.GetStringBuilder().ToString();
}
}
}
}
I found a better way to render razor view page when I got error with the methods above, this solution for both web form environment and mvc environment.
No controller is needed.
Here is the code example, in this example I simulated a mvc action with an async http handler:
/// <summary>
/// Enables processing of HTTP Web requests asynchronously by a custom HttpHandler that implements the IHttpHandler interface.
/// </summary>
/// <param name="context">An HttpContext object that provides references to the intrinsic server objects.</param>
/// <returns>The task to complete the http request.</returns>
protected override async Task ProcessRequestAsync(HttpContext context)
{
if (this._view == null)
{
this.OnError(context, new FileNotFoundException("Can not find the mvc view file.".Localize()));
return;
}
object model = await this.LoadModelAsync(context);
WebPageBase page = WebPageBase.CreateInstanceFromVirtualPath(this._view.VirtualPath);
using (StringWriter sw = new StringWriter())
{
page.ExecutePageHierarchy(new WebPageContext(new HttpContextWrapper(context), page, model), sw);
await context.Response.Output.WriteAsync(sw.GetStringBuilder().ToString());
}
}
The easiest way for me was:
public string GetFileAsString(string path)
{
var html = "";
FileStream fileStream = new FileStream(path, FileMode.Open);
using (StreamReader reader = new StreamReader(fileStream))
{
html += reader.ReadLine();
}
return html;
}
I use this for emails and make sure that the file only contains CSS and HTML

Render Full View as String in ASP.NET

I have found this code to render a partial view as a string:
public static string RenderPartialToString(string controlName, object viewData)
{
ViewPage viewPage = new ViewPage() { ViewContext = new ViewContext() };
viewPage.ViewData = new ViewDataDictionary(viewData);
viewPage.Controls.Add(viewPage.LoadControl(controlName));
StringBuilder sb = new StringBuilder();
using (StringWriter sw = new StringWriter(sb))
{
using (HtmlTextWriter tw = new HtmlTextWriter(sw))
{
viewPage.RenderControl(tw);
}
}
return sb.ToString();
}
However I need to render a full view as a string (which contains ViewData).
What is the best way to do this?
Rendering a full view as string:
private string RenderViewToString(string viewName, object model=null)
{
if (string.IsNullOrEmpty(viewName))
viewName = ControllerContext.RouteData.GetRequiredString("action");
if (model != null)
ViewData.Model = model;
// you can pass in additional arguments to this function
// and manipulate the ViewData further if you need to
using (var sw = new StringWriter())
{
var viewResult = ViewEngines.Engines.FindView(ControllerContext, viewName, null);
var viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
viewResult.View.Render(viewContext, sw);
return sw.GetStringBuilder().ToString();
}
}
Use like this, if you want to render a page without model:
var text = RenderViewToString("Index");
and like this, if you want to render a page with a model
var text = RenderViewToString("OtherPage", model);

Not able to get query string

I am using the below code for setting URL in the current http context
public HttpContext SetNewHttpContext(string uRL)
{
var httpRequest = new HttpRequest("", uRL, "");
var httpResponse = new HttpResponse(new StringWriter());
return new HttpContext(httpRequest, httpResponse);
}
Invoking it as under
HttpContext.Current = SetNewHttpContext("http://root/test.aspx?userid=319279549&name=xyz");
var val = HttpContext.Current.Request.QueryString["userid"];
But i am not able to get the value of the querystring(userid here) and getting null.
Why?
Please help
Uri tempUri = new Uri("http://root/test.aspx?userid=319279549&name=xyz");
string sQuery = tempUri.Query;
NameValueCollection queryString =
System.Web.HttpUtility.ParseQueryString(sQuery ,Encoding.UTF8);

Manually converting result dataset to JSON

I have DataReader that holds the results from a stored procedure caal. The results consist of two fields ...
UserID
UserName
Normally I bind these results to an ASP.NET dropdownlist control ...
ddlUserList.DataSource = rdr // rdr is the DataReader
ddlUserList.DataTextField = "UserName"
ddlUserList.DataValueField = "UserID"
ddlUserList.DataBind()
However I am now trying to accomplish the same thing using jQuery AJAX. What I am stuck on is how to manually convert the dataset held in the DataReader to JSON. How are multiples values separated? Does this look correct?
{{"UserID":1, "UserName":"Bob"}, {"UserID":2, "UserName":"Sally"},{"UserID":3, "UserName":"Fred"}}
I realize there are libraries out there such as JSON.NET to handle the serialization but I am in the learning stage now and want to make sure I understand everything from the bottom up.
Was wondering if you have tried using System.Web.Script.Serialization.JavaScriptSerializer library?
You can look at Rick Stahl's blog on this:
http://www.west-wind.com/weblog/posts/737584.aspx
Or you could also do something like create a method that will pull out data from the datareader and place it in a list of objects. (See code below). These list of object will be serialized using the JavaScriptSerializer library.
Hope this helps!
public class User
{
public int UserId { get; set; }
public string UserName { get; set;}
}
public class DataLayer
{
public string GetUsers(string connString)
{
string result = null;
List<User> users = null;
// get data using SqlReader
using(var conn = new SqlConnection(connString))
{
using(var cmd = new SqlCommand{ Connection = conn, CommandText = "SELECT * FROM Users", CommandType = CommandType.Text })
{
conn.Open();
var reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
if(!reader.HasRows)
return null;
//convert data reader to a list of user objects
users = (List<User>)ConvertToList<User>(ref reader);
conn.Close();
}
}
//convert list of objects in list to json objects
var jsonSerializer = new System.Web.Script.Serialization.JavaScriptSerializer();
result = jsonSerializer.Serialize(users);
return result;
}
public static IList<T> ConvertToList<T>(ref SqlDataReader reader)
{
IList<T> result = null;
if (reader.IsClosed)
return result;
result = new List<T>();
T item = default(T);
while (reader.Read())
{
//create item instance
item = (T)Activator.CreateInstance<T>();
//get class property members
var propertyItems = item.GetType().GetProperties();
//populate class property members with data from data reader
for (int ctr = 0; ctr < reader.FieldCount; ctr++)
{
if(reader.GetName(ctr) == propertyItems[ctr].Name)
propertyItems[ctr].SetValue(item, UtilsHelper.GetValue<string>(reader[ctr]), null);
}
//add item to list
result.Add(item);
}
reader.Close();
reader.Dispose();
return result;
}
}

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