C# - Create A New Instance Of A Type Without Reflection?

Jan 14, 2011

I have a function that at the moment takes a Type variable. This function sticks it in a list and such and eventually needs will create a class of that type. Right now I do that with

object o=MyType.GetConstructors()[0].Invoke(new object[0]);

which is pretty hacky and also will not work in medium trust due to reflection(I think). Is there a better way of doing this without reflection? The Type is defined this way as part of a function. I need the class to be created "lazily" because it may not be created in the application if it's not needed. I use it for example like


Note, I'm open to suggestions on changing the function calling. I just need the object to be created lazily and for to store the type(or however to create an object of the type) in a list.

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C# - Trying To Create Instance Of Class By Using Reflection

Apr 16, 2010

I am trying to create instance of class by using reflection in ASP.net web site. Class ClassName is defined and located in App_code folder. Following line returns null, what could be wrong.

Type type = Type.GetType("NameSpace.ClassName", false, true);

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C# - Create An Instance Of A Web Control Using Reflection?

Oct 20, 2010

How can I create an instance of a web control at runtime using reflection? I created a series of controls that implement a common interface and I would like to create these controls based on the name of the control which is stored in my database.

I have attempted (and failed) to create an instance of these controls using Activator.CreateInstance in the following ways:




...and both return null.

I've also attempted to simply get the type of the control by trying..

Type t = Type.GetType("controls_myusercontrol_ascx");


Type t = Type.GetType("MyUserControl");

...and it returns null.

If I explicitly declare an object as controls_myusercontrol_ascx or MyUserControl, there is no issue -- but it can't be found with reflection.

Is it possible to create web user controls using reflection at run time? If so, how can I?

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Web Forms :: How To Create An Instance Of A Type From Type

Feb 1, 2010

How would I create an instance of a type if all I have is the type in string form?


Now if I wanted to create and instance of myType how would I do that ?

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C# - Create And Instance Of MyClass Using The Type?

Sep 24, 2010

Bit of a puzzler, I have a generic class

public abstract class MyClass<T> : UserControl

and I have got a type like this

Type type = Type.GetType("Type From DB as String", true, true);

and I want to create and instance of MyClass using the type... But this doesn't work.

MyClass<type> control = (MyClass<type>)LoadControl("/UsercControl.ascx");

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C# - Creating A Generic IList Instance Using Reflection?

Feb 4, 2010

I am trying to create a generic list of objects using reflection. The below code throws an error Cannot create an instance of an interface. . I could change the IList to List and it works fine, but I was wondering if there is way to get this working with an IList.

var name = typeof (IList<T>).AssemblyQualifiedName;
Type type = Type.GetType(name);
var list = Activator.CreateInstance(type);

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.net - Generic Way Of Checking Property Type Using Reflection

Mar 25, 2011

I am trying to set property value using reflection as below. I wanted to know if there is any generic way of finding the property type instead of doing it int he below way.

string currentlblTxt;
string currentTxt;
Assembly assembly = Assembly.GetAssembly(typeof(myAdapter));
myAdapter currentEventObject = (myAdapter)assembly.CreateInstance(myClassName);

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Use System.Type.InvokeMember() / Invoke Method Dynamically Using Reflection?

Feb 24, 2011

I understood that we can use System.Type.InvokeMember() to invoke method dynamically using Reflection, but I couldn't get proper example to show how to work on it. Can anyone please explain how to do it in
Visual Studio 2010

Just for practice purpose I have created one class called MathFunctions like below:
PrinicipalAmount, double
TimePeriod, double RateOfInterest)
(PrinicipalAmount * TimePeriod * RateOfInterest) / 100.0;

how can I invoke above method SimpleInterest with its parameters without instantiating the class?

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Custom Server Controls :: Create Class Copy Using Reflection

Sep 22, 2009

Using reflection, can you do something like this?


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Comparing An Instance Of Type To Type

Dec 31, 2010

I have a basic question about comparing the type of a variable to a specific type. If I have variable A and variable B, both an instance of a certain type, then I know I can compare the types by getting A.GetType and B.GetType, I can also use IsAssignableFrom and IsSubclassOf for more advanced things. However if I only have variable A and I want to know if variable A is of type MyCustomType, as I see it now I first have to create an instance of MyCustome Type, get the type from it and then compare it to the type of A like in the next Example:

string A = "test";
MyCustomType B = new MyCustomType();
Type typeToCompare = B.GetType();
if (A.GetType().FullName == typeToCompare.FullName) {...}

So if I need to know if A is of MyCustomType isn't there an easyer, shorter alternative that I can just try something like the following (which is ofcourse not possible):

if (A.GetType == MyCustomType....) {...}

so without first having to create an instance of the type simply to extract the type from it.?

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C# - How To Create A Generic/parent Type That You Could Send To Methods Without Having To Define An Overload For Each Type

Mar 5, 2011

I'm trying to create a validation layer that will contain methods to validate all my objects (in my Business Objects layer) .. but when I try to reference both the validation and business objects to each other I get a circular dependency error .. so I've decided to create a new layer (BLL) to validate the objects for me and I'll be able to reference both the validation and the object layers.

so I want to build some kind of class/interface -I don't know what fits more- to be like a generic type or a parent type that my method could accept it as a parameter and check for it's Name/ID property. Instead of defining a new method overload for each object type I have

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MVC :: Can't Create Strongly Type View User Controls/ Could Not Load Type 'System.Web.Mvc.ViewUserControl<MyModel>'

Jun 5, 2009

I inherit from ViewUserControl and it works. I then add my model to the end <> using the full namespace path and now I get

Could not load type 'System.Web.Mvc.ViewUserControl<MyModel>'.

Doesn't matter what I use inside <>. I could set it to string, List<string>, whatever. It just won't load it anymore. Of course, in a brand new test mvc application, it does work.

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Access Of Shared - Constant - Enum Member Or Nested Type Through An Instance

Jan 7, 2009

I got an error in line 9 which says, Warning 1 Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.


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JQuery ::create A 'hyperlink' Type And A 'pdf' Type?

Feb 28, 2011

I am struggling to find relevant documentation on this, what I basically want to do is to create a 'hyperlink' type and a 'pdf' type that I can put into my XML file and use to link to a webpage or a PDF, with the relevant icon.

Here is my JQuery :


And my XML :


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Cannot Create New Instance Of Class

Feb 2, 2009

how to create a new instance of my class (say X) in another class? HWenever I try it I get the familiar error " The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)

Yet I have this class sitting in my App_Code folder. However, I am not using Visual Studio. Is it not possible to do this outside of VS, say Dreamweaver or in another IDE?

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SQL Server :: How To Create The New Instance Along With PC Name

Sep 26, 2010

I have a question regading sql name instance ???

When ever i create new instance in sql server 2005 , it use to create the new instance along with my PC name.

For Eg :

My PC Name is Web and New instance name is Busiwork it use to create like WebBusiwork. But i need just the sql instance name of my server as Busiwork.

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How To Create New Instance Of An Object

Aug 5, 2010

As some may be aware, I recently posted about high memory usage on my website and I have an idea that my thumbnailer may have something to do with this as I am not actively disposing of the instance when it has been used due to my misunderstanding how it works.

I am now looking at my code for the thumbnailer and would like some advice on when something would actually need disposing of, is it ONLY when you create a new instance of an object?


Target := System.Drawing.Bitmap.Create(Trunc(Width), Trunc(Height));
MyImage := Target.FromFile(PhotoPath);

So, my question would be, do I need to dispose of both Target and MyImage to make sure the GC does what it needs to do properly?

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C# - How To Create Instance Of A Class Only Once

Apr 4, 2011

A instance of a class is created in the partial class of an aspx page.Under page_load or button click method I'm trying to set the value to the class. but when each postback takes place new instance is created and I'm losing the previous value.

public partial class DatabaseSelection : System.Web.UI.Page
DBProperties dbpro;
Metadata obmeta;
protected void Page_Load(object sender, EventArgs e)
if (!IsPostBack)
dbpro = new DBProperties();

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C# - Use String Value To Create New Instance?

May 6, 2010

I have a few classes: SomeClass1, SomeClass2.

How can I create a new instance of one of these classes by using the class name from a string?

Normally, I would do:

var someClass1 = new SomeClass1();

How can I create this instance from the following:

var className = "SomeClass1";

I am assuming I should use Type.GetType() or something

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How To Create Instance Of A Class Dynamically

May 21, 2010

I wanna do smth like this:


Does anyone have a recommendation how this is archievable? I am trying to pass in the Type to the method and then create an instace of it and then access the properties in it.

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C# - How To Create New Instance Of A Page And Obtain URL

Aug 6, 2010

i'm a beginner web programmer. I've been coding desktop applications primarily. Right now, i have created this web app, in Silverlight, that uses a web service of my own for querying the database. The thing is, one of the app functionalities is the ability to open PDF files. I know that silverlight won't let you do this, but using an IFrame on top of the silverlight application you are able to display a page with de pdf file (using acrobat plug in). So here's the problem, my silverlight app passes the pdf path to the web service and, in return, the web service would create a new Page and pass the new page URI back so that it can be displayed on the IFrame:


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Create A Usercontrol Instance Programmatically?

Feb 16, 2011

I have a UserControl that I need to add dynamically. I tried to follow this MSDN article, but I'm not having any success....[URL]

The UserControl is basically an image gallery, and it loads some pictures based on an ID. My idea was to make this ID available as a property. Then when I create an instance of the control, I could set this ID and add it to the form.

I added a reference to the control in the .aspx page that will use it, like this:

<%@ Reference Control="~/PictureGallery.ascx" %>

And in the UserControl I added a ClassName like this:

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="PictureGallery.ascx.cs"
Inherits="PictureGallery" ClassName="PictureGallery" %>

When I try to create an instance in the .aspx.cs like the article suggests, Dim gallery As ASP.PictureGallery, I get an "Type ASP.PictureGallery is not defined".

The article mentions a namespace, ASP, and I tried importing it to the .aspx.cs with no luck. So, I'm not able to get a reference to the UserControl.

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MVC :: Razor - Create Instance Of View?

Oct 12, 2010

In my controller method, I'm trying to create an instance of a View (cshtml file) before I wrap it around an ActionResult and return it.Since there is no "class" for Razor Views to speak off, how does one go about creating an instance of a Razor View?

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C# - Cannot Create Instance Of Abstract Class?

Mar 31, 2010

I am trying to compile the following code and i am getting the error:

Cannot create instance of abstract class .

m_objExcel = new Excel.Application();
m_objBooks = (Excel.Workbooks)m_objExcel.Workbooks;
m_objBook = (Excel._Workbook)(m_objBooks.Add(m_objOpt));
m_objSheets = (Excel.Sheets)m_objBook.Worksheets;
m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(1));
// Create an array for the headers and add it to cells A1:C1.
object[] objHeaders = {"Order ID", "Amount", "Tax"};
m_objRange = m_objSheet.get_Range("A1", "C1");
m_objRange.Value = objHeaders;
m_objFont = m_objRange.Font;
// Create an array with 3 columns and 100 rows and add it to
// the worksheet starting at cell A2.
object[,] objData = new Object[100,3];
Random rdm = new Random((int)DateTime.Now.Ticks);
double nOrderAmt, nTax;
for(int r=0;r<100;r++)
objData[r,0] = "ORD" + r.ToString("0000");
nOrderAmt = rdm.Next(1000);
objData[r,1] = nOrderAmt.ToString("c");
nTax = nOrderAmt*0.07;
objData[r,2] = nTax.ToString("c");
m_objRange = m_objSheet.get_Range("A2", m_objOpt);
m_objRange = m_objRange.get_Resize(100,3);
m_objRange.Value = objData;
// Save the Workbook and quit Excel.
m_objBook.SaveAs(m_strSampleFolder + "Book2.xls", m_objOpt, m_objOpt,
m_objOpt, m_objOpt, m_objOpt, Excel.XlSaveAsAccessMode.xlNoChange,
m_objOpt, m_objOpt, m_objOpt, m_objOpt);
m_objBook.Close(false, m_objOpt, m_objOpt);

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How To Create Instance Of Excel On Remote Server

Nov 28, 2008

We need to create a fairly complex excel document on the fly for our users. Unfortunately, these aren't all internal and many customers still use versions of excel prior to 2007. Thus we can't use the xml format. (and the 2003 xml format doesn't do images)

I need to be able to instantiate excel on a different machine (so it's off our webserver) to generate binary excel files. I'm at my wits end. It just refuses to work, I keep getting error 80070005 (access denied). Yet in the dcom settings we're gone so far as to grant everyone full access and still, the same error.

Ironically, the old vb6 app has no problem calling CreateObject("Excel.Application", server).

Yet our .NET app attempts the following


and it fails with the error, so we tried importing the vb namespace so I could call Interaction.CreateObject and still I get the error

Has anyone had success at this? Or barring that, a way to convert a 2007 open xml excel file to a 2003 binary format on the server?

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How To Create Multi Instance Application In Azure

Feb 6, 2010

I want to create multiinstance application in Azure. and then demontrate that if one of the instance is down other instance is working fine. How should I achive that.

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Cannot Create An Instance Of A COM Component On A Server Side

Jul 20, 2010

I'm trying to use MS IME on a server to retrieve some Japanese info in a silverlight app. The app accesses to the server by using WCF, but when calling a CoCreateInstance to create a IFELanguage2, it gives me -2147467262. The same code I'm using on the server actually works pretty fine on a WPF app.

Here is the code,

// ...omit
Guid imeGuid;
int errCode = Ole32.CLSIDFromString("MSIME.Japan", out imeGuid);
Guid feLangIID = new Guid(Constants.IID_IFELanguage2);
IntPtr ppv;
errCode = Ole32.CoCreateInstance(imeGuid, IntPtr.Zero, Ole32.CLSCTX.CLSCTX_ALL, feLangIID, out ppv);
WinBase.CheckError(errCode); // errCode is 2147467262
IFELanguage IfeLanguage = Marshal.GetTypedObjectForIUnknown(ppv, typeof(IFELanguage)) as IFELanguage;
errCode = IfeLanguage.Open();
// ...omit

Do I need to setup anything to use the MS IME on a server side? I'm running the app on the following environment, IIS7 .NET Framework 4.0 Windows 7 pro 64 bit VS2010

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MVC :: Cannot Create An Instance Of The Abstract Class Or Interface?

Dec 12, 2010

Error 1279 Cannot create an instance of the abstract class or interface 'System.Web.Mvc.FileResult'


I am using MVC 2. The same code works in my onather application. I have no idea about this error.

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MVC :: System.MissingMethodException: Cannot Create An Instance Of An Interface

Sep 6, 2009

I have a controller that is used for searching: searchController. It takes user input, searches the model for it and then forwards the result to another controller that then displays the results.

Search Controller:


Second Controller used for displaying the information:


From my attempts at debugging I think a problem lies with the redirect but I'm having a hard time figuring out what is wrong because the error message I get is unknown to me: System.MissingMethodException: Cannot create an instance of an interface. That message is displayed right when redirect is called.

Maybe I can't pass an IQueryable between controllers?

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Create Instance Of Class And Pass From Web Form - Resource

Jul 13, 2009

How do I create an instance of a class and pass it from one web form to another. Is there a resource which explains the code in the time tracker starter kit?

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