I am receiving "Object reference not set to an instance of an object." when I am trying to add access token from fb to the httpcurrent.session object.
I have the value in the var accessToken and when I am trying to put it in the session I am getting the error.
Please refer to the image:
You need to enable session state in an HttpHandler, so you have to implement
System.Web.SessionState.IRequiresSessionState
Change to the following:
public class FacebookLogin : IHttpHandler, System.Web.SessionState.IRequiresSessionState
Related
I'm attempting to pull out the Created UTC value from my Orchard project but I keep getting "object is null"
Here is my code
IUser loggedOnUser = _orchardServices.WorkContext.CurrentUser;
var userCreatedDate = loggedOnUser.As<CommonPart>().CreatedUtc;
When it hits the second line it throws the exception of "Object reference not set to an instance of an object".
Looking at this link my code should work fine.
User content item contains only a UserPart. If you need to access created/modified dates, you need to attach a CommonPart to it via data migrations, like this:
public int Create() {
ContentDefinitionManager.AlterTypeDefinition("User", cfg => cfg.WithPart("CommonPart));
return 1;
}
Just keep in mind that it won't affect existing users automatically - you would have to go through them one by one and hit "Save" for the part to be created.
A simple question but I'd rather ask since I had problem with it two times.
I am trying to retrieve hostname from the url in ASP.NET project. The code is actually not in a web page but in a class (part of the domain). System.Web is included in the headers. When I try to use Request.QueryString it is not recognized. Even worse if I try HttpContext.Current, I get this error
'System.Web.HttpContext.Current' is null
Here is my code
using System.Web;
public class MyNightlyJob : AbstractJob
{
public override void ExecuteJob(IJobExecutionContext context)
{
HttpContext.Current.Request.ServerVariables["HTTP_HOST"]; // does not work
Request.ServerVariables["HTTP_HOST"]; // this does not work also
}
}
What am I missing? Note that my question is actually about Request.ServerVariables but if one works, the other will work too.
Note that Request.ServerVariable is not recognized in the code at all. HttpContext.Current is recognized but I get run time error for that.
You need to check if HttpContext.Current is a null. If it is null then its not in the right context to be retrieved.
If you can modify the function, I would pass the HttpContext.Current as a variable or pass the host as a variable.
I'm writing an ASP.NET C# web site that needs to access data from a database and show it to the user for viewing and editing. The specific data it accesses is based on the user who logs in, and I need for multiple users to be able to use the site simultaneously, viewing and editing different data as they do so. I stumbled upon the concept of Session States, and after a lot of reading and not as much understanding. I've come across a problem.
In my default page, I do this to create a Session variable:
Session.Add("UserData",userdata);
I have also tried this:
Session["UserData"] = userdata;
Then in a later page, I do this to try to call it:
object myobject = Session["UserData"];
This gives me an error, saying that Session["UserData"] is not set to an instance of an object. This is the method everyone seems to be using, is there something I'm missing?
My site is configured on IIS to have the Session State Mode set to "In Process", but most people seem to set this manually using their web.config file. However, when I try to do this in my web.config file I am always greeted with "unrecognized configuration section". My compiler doesn't know what this is:
<sessionstate mode="inproc"/>
EDIT, more detailed code:
MyClass userdata = new MyClass();
userdata.name = "myname";
userdata.number = 5;
Session["UserData"] = userdata;
later...
MyClass mydata = (MyClass)(Session["UserData"]);
This returns the error that Session["UserData"] is null.
The fact that you can't set the session mode in the web.config is a red flag to me of something weird and smelly going on. So ...
Check that the session mode is under the system.web element of the web.config otherwise it won't be valid.
Check that enableSessionState hasn't been set to false in either the web.config or the page directive
Try to rule out IIS. If possible convert your website to a web app and run through visual studio so it starts with it's own built in web server. What happens then? Is the Session state back?
It should n't make a difference but if you are not doing the test in Page_Load then just try it there - just in case you are doing these tests somewhere unusual.
Whatever the answer is to this when we know it will be headachingly obvious. I'm geninuely looking forward to finding out what it is. Good luck
Session variables are good to manage multiple users on your website, but to initialize them you should use the Global.asax file in your web application. This file has two methods specifically for Session variables, Session_Start and Session_End. To initialize your Session variable you would use code liked the following in Global.asax:
void Session_Start(object sender, EventArgs e)
{
// initialize session variable
Session["MySessionVar"] = 1;
}
Also you may have to cast the value of your session variable if you are doing operations on it like +, for example if you have a session variable holding an integer value, you may have to do like the following:
Session["MySessionVar"] = ((int) Session["MySessionVar]) + 1;
Also, if you try to use your session variable outside of a method like Page_Load or other method, like trying to use it as a property of the System.Web.UI.Page class in your C# code behind file, that may not work, you can only use your session variables within a method.
I would search for any calls to Session.Clear or Session.Abandon to see if your session is being purged in between those two actions.
You could also hook up to the Session_End event and see if that gets hit sometime in between the two calls.
Where you have
Session.Add("UserData",userdata);
you want to check the value you need to cast the object with (string) like this
string userdata= (string)(Session["UserData"]);
you could then run a check to see
if(string.IsNullOrEmpty(userdata))
but not sure how you are initializing and assigning a a value to userdata
Does it complain the your myobject is null or that Session is null? When you try to retrieve the value you are doing this from the method of what class?
Yet another question - by any chance are you trying to access it in a parallel thread?
I have a WCF service that is using a custom UsernamePasswordValidator. The validator needs to access my entity framework context.
I would like to create one ObjectContext for the entire service call and then destroy/dispose it at the end of the call. So I created a singleton static class that provided this functionality, however, what's happening now is that if two service calls happen concurrently, one of the calls disposes the singleton.
I either keep a local reference to the ObjectContext, in which case the second service to use it sees it as disposed and throws and error, or, I put a wrapper property around the Singleton class wherever I need it and then all my changes get thrown away because I'm getting a new instance of the object if another call has disposed it.
So basically my question is how do I instantiate an ObjectContext per service call?
NOTE: The instance needs to be accesible in both the service code AND the custom UsernamePasswordValidator code.
I can't just do it in the constructor or use a using statement because then the custom UsernamePasswordValidator doesn't have access to it. Is there a way to have a static class per call? It does sound impossible, but what's the way around this? Should I be caching the object in a session?
My service is hosted in IIS.
UPDATE:
So I've nailed this down to storing state in the InstanceContext using an IExtension object. But How do I access the current InstanceContext in a UsernamePasswordValidator?
Ok, so in the end I solved it by using the following static class and relying on ASP.NET to cache the context for me.
I'm not sure if this is the best way to do things, but this allows me to use one ObjectContext per request so I'm not spinning up too many and this also means I don't have to use a lock on the object which would become a nightmare if many users were using the service.
public static class MyContextProvider
{
public static MyModel Context
{
get
{
if (HttpContext.Current.Items["context"].IsNull())
{
HttpContext.Current.Items["context"] = new MyModel();
}
return HttpContext.Current.Items["context"] as MyModel;
}
}
}
Then wherever I need an ObjectContext in the app I just call
var context = MyContextProvider.Context;
You have one instance per call, you also have 1 call per instance.
So it should be very simple, use a using () { } block in the toplevel of your OperationContract method.
Ok, here is the class with thread-safe static method that provides single ObjectContext entity model object for any WCF service call and automatically dispose it at the end of call:
public static class EntityModelProvider
{
private static readonly Dictionary<OperationContext, MyEntityModel> _entityModels = new Dictionary<OperationContext, MyEntityModel>();
public static MyEntityModel GetEntityModel()
{
if (OperationContext.Current == null)
throw new Exception("OperationContext is missing");
lock (_entityModels)
{
if (!_entityModels.ContainsKey(OperationContext.Current))
{
_entityModels[OperationContext.Current] = new MyEntityModel();
OperationContext.Current.OperationCompleted += delegate
{
lock (_entityModels)
{
_entityModels[OperationContext.Current].Dispose();
_entityModels.Remove(OperationContext.Current);
}
};
}
return _entityModels[OperationContext.Current];
}
}
For your service, you can specify a service behaviour which details the instance mode of the service:
[ServiceBehaviour(InstanceContextMode = InstanceContextMode.PerCall)]
public class MyService : IMyService {
ObjectContext context;
}
A cleaner way may be to use the ServiceAuthenticationManager, which is in .NET 4.
http://msdn.microsoft.com/en-us/library/system.servicemodel.serviceauthenticationmanager.aspx
From the Authenticate method (which you'll override) you can access the Message object and set properties on it. I've not used it in anger, so YMMV :)
EDIT the problem with this approach is that you don't have the Username and Password, so will still need the custom Authentication.
Take a look at the UsernameSecurityTokenAuthenticator...
http://msdn.microsoft.com/en-us/library/system.identitymodel.selectors.usernamesecuritytokenauthenticator(v=vs.90).aspx
Further reading from my research:
Answers to this question gives some hints about how to use it:
Custom WCF authentication with System.ServiceModel.ServiceAuthenticationManager?
If you can read (or ignore) the Russian, I found useful hints at:
http://www.sql.ru/forum/actualthread.aspx?tid=799046
This rather good CodeProject article goes further (encryption and compression as well as custom authorization)
http://www.codeproject.com/Articles/165844/WCF-Client-Server-Application-with-Custom-Authenti
Why not pass in the context into your CustomValidator when you assign to the service - store your object context in your validator, and in the overridden validation method new it up if need be. Then you still have access to the object through the Services CutomUserNameValidator ..
Depending on what you are asking :
Create your separate ObjectContext class as a dynamic object - add that as a property to you CustomValidator.
In your custom Validator - you can now check if the object is disposed and create the object again if need be.
Otherwise if this is not what you are after - just store the Context in the validator - you still have access on server side.
The code here is just generalized idea - I am just posting it as a frame of reference so you can have an idea of what I talking about.
public DynamicObjectContextObjectClass
{
ObjectContext internalObjectContext;
}
public class ServiceUserNamePasswordValidator : UserNamePasswordValidator
{
public DynamicObjectContextObjectClass dynamiccontext;
public override void Validate(string userName, string password)
{
if(dynamiccontext.internalObjectContext.isdisposed)
{
dynamiccontext.internalObjectContext = new Context;
}
try
{
if (string.IsNullOrEmpty(userName) || password == null)
{
//throw new ArgumentNullException();
throw new FaultException("Username cannot be null or empty; Password cannot be null and should not be empty");
}
}
}
}
I get this error when i have this in my codebehind: if(Page.User.Identity.IsAuthenticated)
System.NullReferenceException: Object reference not set to an instance of an object.
This error show when i use context.RewritePath method
http://localhost/page.apsx?id=22 --> http://localhost/hello-world/
Page.User.Identity.IsAuthenticated return True when i go to page.aspx?id=22 but i get
System.NullReferenceException: Object reference not set to an instance of an object.
error when i go to /hello-world/ url.
If the url.Contains("List") then rewrite the url like this:
context.RewritePath(Utility.WebRoot + "List/Add.aspx", false);
My rewriter is not more complicate then that.