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European ASP.NET Hosting - Amsterdam :: Tips to Fix FileUpload Control is not Working in UpdatePanel

clock August 30, 2013 11:50 by author Scott

In this article I will explain with example how to upload Image/ file through File Upload Control that is placed inside Update Panel in asp.net Ajax using both C# and VB.Net languages. Many of the developers face a very common problem i.e. “FileUpload control is not working in update panel in asp.net”. I will also explain the reason and solution of this problem.

The FileUpload control doesn’t work for uploading image using Asynchronous postback when placed in the Update Panel since FileUpload control required full postback to get the image. If you check FileUpload1.HasFile method or FileUpload1.FileName property then it is null. That is because the update panel does not retain the file inside the FileUpoad control.

To solve the issue we need to set the Button that is uploading the image to be PostBackTrigger instead of AsyncPostBackTrigger. By doing so the upload button will cause the full post back and get and retain the image in the FileUpload control whenever clicked on.

So set it as:

<Triggers>
       <asp:PostBackTrigger ControlID="btnUpload" />
</Triggers>

How it works:

- In the <Form> tag of the design page (.aspx) places a FileUpload Control and a Button control from the standard category of the visual studio’s toolbox. Also place ScriptManager from the AJAX Extension category.

- Also create a folder in the root directory of your project and give it name “Images”. We will store our uploaded image in this folder. Uploaded images will be prefixed with a random unique name using the Guid.NewGuid() to avoid the duplicate name problem

<div>
    <fieldset style="width:250px;">
    <legend>Upload file example in asp.net</legend>
    <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
    <table>
    <tr>
    <td>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
            <asp:FileUpload ID="FileUpload1" runat="server" />
            <asp:Button ID="btnUpload" runat="server" Text="Upload"
                onclick="btnUpload_Click" /><br />         
            <asp:Image ID="imgShow" runat="server" Width="150px" />
        </ContentTemplate>
       <Triggers>
       <asp:PostBackTrigger ControlID="btnUpload" />
       </Triggers>
        </asp:UpdatePanel>
    </td>
    </tr>
    </table>
    </fieldset>       
    </div>

C#.Net Code to upload image through FileUpload Control in Update Panel using Asp.Net

- In the code behind file(.aspx.cs) write the code on the upload button’s click event as:

protected void btnUpload_Click(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile)
        {
            string ImgPath = Server.MapPath("~/Images/" + Guid.NewGuid() +  FileUpload1.FileName);
            FileUpload1.SaveAs(ImgPath);
            string ShowImgPath = ImgPath.Substring(ImgPath.LastIndexOf("\\"));
            imgShow.ImageUrl = "~/Images" + ShowImgPath;
        }
        else
        {
            ScriptManager.RegisterStartupScript(this, this.GetType(), "Message", "alert('Please select the image to upload');", true);                     
        }
    }

VB.Net Code to upload image through FileUpload Control in Update Panel using Asp.Net

- First design the page as mentioned in the source code above but replace the line

<asp:Button ID="btnUpload" runat="server" Text="Upload" onclick="btnUpload_Click" /> with the line  <asp:Button ID="btnUpload" runat="server" Text="Upload"/>

- In the code behind file(.aspx.vb) write the code on the upload button’s click event as

Protected Sub btnUpload_Click(sender As Object, e As System.EventArgs) Handles btnUpload.Click
        If FileUpload1.HasFile Then
            Dim ImgPath As String = Server.MapPath(("~/Images/" & Convert.ToString(Guid.NewGuid())) + FileUpload1.FileName)
            FileUpload1.SaveAs(ImgPath)
            Dim ShowImgPath As String = ImgPath.Substring(ImgPath.LastIndexOf("\"))
            imgShow.ImageUrl = "~/Images" & ShowImgPath
        Else
            ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "Message", "alert('Please select the image to upload');", True)
        End If
    End Sub



Press Release :: European HostForLIFE.eu Proudly Launches ASP.NET MVC 5 Hosting

clock August 28, 2013 10:35 by author Ronny

European Windows and ASP.NET hosting specialist, HostForLIFE.eu, has announced the availability of new hosting plans that are optimized for the latest update of the Microsoft ASP.NET Model View Controller (MVC) technology. The MVC web application framework facilitates the development of dynamic, data-driven websites.

The latest update to Microsoft’s popular MVC (Model-View-Controller) technology,  ASP.NET MVC 5 adds sophisticated features like single page applications, mobile optimization, adaptive rendering, and more. Here are some new features of ASP.NET MVC 5:

- ASP.NET Identity
- Bootstrap in the MVC template
- Authentication Filters
- Filter overrides

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European ASP.NET 4.5 Hosting - Amsterdam :: Web API. VB.NET Example ASP.NET 4.5

clock August 15, 2013 08:55 by author Scott

The new feature that appeals to me is the new “Web API” which eases the development of REST and AJAX APIs (API is the new Microsoft jargon for a web service!)

Wanting to have a play with this new feature, I fired up Visual Studio Express 2012 and created a standard web application in vb.net. Although many examples on the web are showing the Web API with MVC, it can be used in any .net application.

 

Using the new “Web API”  requires two parts.

1. Setup the controller class that will perform the logic.

2. Setup up route tables in your global.asax.vb file, to correctly “route” the client request to the correct controller class.

So down to code. The examples below assume a GET request to the Web API Server.

1. Create a standard web application, remembering to specify .net 4.5 as the target framework.

2. Create a new folder within the application called “Controllers”. See Picture below.

3. Within this folder, create a new “Web API Controller Class”, by right clicking on the Controllers folder and clicking Add. Then choose “Web API Controller Class” from the list as shown below

4. When naming this new controller class, remember to leave the word controller at the end of the name, otherwise the routing won’t work! As you can see below, I called my class VenueApiController.vb

5. When you open this new class, you will see some get, post,delete functions already filled in. I just created new functions to suit my client data requirements.

The sample data that I am using is for a project we have been working on call nejola.com. This allows local businesses to “push” their deals to Android smartphone users in the locality.

We have some test data in the SQL Server, so used this to try the Web API out.

The first function that I created returned a full list of the test venues available. I named this function GetVenues. No search data was needed to be passed to the function and I wanted the result fetched as a dataset to the client. The beauty of the “Web API” is the data is then presented to the client depending upon the headers of the calling client. For example an ajax call will return the data in a json format

Public Function GetVenues() As DataSet

Try

                Using sqlConn As New
SqlConnection(ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString)
                    Dim sqlComm As SqlCommand = New SqlCommand
                    sqlComm.Connection = sqlConn
                    sqlComm.CommandText = "SELECT * From df_Locations"
                    Dim sqlDataAdapt As SqlDataAdapter = New SqlDataAdapter(sqlComm)
                    Dim ds As DataSet = New DataSet
                    sqlDataAdapt.Fill(ds)
                    sqlDataAdapt.Dispose() : sqlComm.Dispose() : sqlConn.Close() : sqlConn.Dispose()
                    ds.DataSetName = "VenueData"
                    ds.Tables(0).TableName = "exgVenuesData"
                    Return ds
                End Using

            Catch ex As Exception

                Return Nothing

            End Try

And that’s it for the data logic ! Nothing too fancy here, just perform some SQL on the SQL server and return the dataset. I would normally call a stored procedure for but this purpose used the commandtext

The function below requires a parameter to be passed, in this case the town name as a string.

Public Function GetVenueByTown(ByVal town As String) As DataSet
Dim sqlConn As SqlConnection = New SqlConnection("Connection info here")
sqlConn.Open()
Dim sqlComm As SqlCommand = New SqlCommand()
sqlComm.Connection = sqlConn
sqlComm.CommandText = "SELECT * From df_Locations WHERE VenueTown = '" & town & "'"
Dim sqlDataAdapt As SqlDataAdapter = New SqlDataAdapter(sqlComm)
Dim ds As DataSet = New DataSet
sqlDataAdapt.Fill(ds)
sqlDataAdapt.Dispose() : sqlComm.Dispose() : sqlConn.Close() : sqlConn.Dispose()
ds.DataSetName = "VenueTownData"
ds.Tables(0).TableName = "EXGTownData"
Return ds
End Function

Now that we have two working functions within the API Class, we need to add routing to call the functions. Users Of Microsoft MVC should be aware of routing and controllers, however for VB.net users this is new with .net 4.5

What the routing and controllers allows us to do is present the URL’s called by the clients  in a nice format. For example to call the GetVenues function above, the client can call :

http://domain.com/venues

To call the GetVenueByTown function and pass the town parameter the client can use :

http://domain.com/venues/town/townname

Ok, so now we need to setup the routing for this to work !

1. Open the global.asax.vb file and look for the sub

Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)

End sub

2. At the top of the page add :

Imports System.Web.Routing

Imports System.Web.Http

3. Here is the code for the GetVenues Function which is the default function called. Add this to the Application_Start Sub.

RouteTable.Routes.MapHttpRoute(name:="Venue", _
routeTemplate:="venues", _
defaults:=New With {.symbol = RouteParameter.Optional, .controller = "VenueApi"})

To break down the above, here is what is happening. This example is the default call, with no parameters being passed to the function.

name:=”Venue” –> This is the name given to this routetable. Each routetable has a different name.

routeTemplate:=”venues” –> This is the actual name that the client will call. In this example http://domain.com/venues.

.controller = “VenueApi” –> This MUST match the name that you gave your controller class without the controller part.

The route code to call the GetVenueByTown function that requires a town parameter to be passed is as follows :

RouteTable.Routes.MapHttpRoute(name:="VenueTowns", _
routeTemplate:="venues/town/{town}", _
defaults:=New With {.symbol = RouteParameter.Optional, .controller = "VenueApi"})

Again a break down of the code is as follows :

name:=”VenueTowns” –> Unique name of the routetable.

routeTemplate:=”venues/town/{town}” –> This is the path that will be entered by the client to get to the correct function. Note we have added the /town/ path and the parameter {town}. This parameter name must match that of the function otherwise the routing won’t work correctly.

controller = “VenueApi” –> This is the same as before and is the controller class without the controller part.



European ASP.NET 4.5 Hosting - Amsterdam :: Performance Improvements in. NET Framework 4.5

clock August 5, 2013 11:56 by author Scott

In this post we are going to discuss the performance improvement in .net framework 4.5 in the area of Just In Time [JIT] compilation. As we know the .net applications are compiled into Intermediate Language [IL] code. This is irrespective of the programming language chosen to develop the application. Now when the application is run, the IL code is read by the CLR and JIT compiled into native code for the particular machine.

So the compilation from the IL Code to the native code happens when the application is actually running. So it shouldn't take a long time to understand that we can improve application performance if we could avoid this. One way to do this is to generate native code using Native Image Generator i.e. NGen.exe. In this case the assembly's native images is loaded from the Native Image Cache from GAC [Global Assembly Cache]. The other option is to still do it dynamically just in time but somehow improve the performance of this JIT compilation. This is exactly what is added to .net framework 4.5.

.net framework 4.5 supports this optimization using application profiles. Now we can enable the profile optimization for an application. Based on the historic profile, it keeps JIT compiling the methods in the background. So when the code is actually needed for execution, it is already in native format so the runtime doesn't have to wait for this.

Now let's see how we can enable an application for this optimization using profiles. In order to support this feature, a new type is added to System.Runtime namespace in mscorlib.dll assembly. As you could guess, this is named as ProfileOptimization class. In the following code, we are setting the directory where the profile would be stored. Next we are starting to profile the application.

const string DirectoryName = "AppProfileOptimization";
const string ProfileFile = "AppProfile"; 

if (!Directory.Exists(DirectoryName))
{
    Directory.CreateDirectory(DirectoryName);


ProfileOptimization.SetProfileRoot(DirectoryName);
ProfileOptimization.StartProfile(ProfileFile);

The CLR creates the file for profile in the specified folder as follows:

Generally, while improving the performance of an application, we look forward to improve the different features provided by the application irrespective of the usage scenarios. Since this JIT compilation is based on past usage of the application, the application would be optimized differently based on these profile files. This is custom optimization of software based on temporal use of the feature. This is because if I have used a feature today, there is a high probability I would be using the application similarly as I am using it today. The runtime is just keeping the usage pattern in persistence and would use it for future use of the application. Since this is based on past profiles, there wouldn't be any advantage the first time the application is running.

It must be remembered that ProfileOptimization is just beneficial for applications running on multicore machines. It's usage is simply ignored if the application is running on a single core machine. There would be no profiling and hence no resulting optimization.

Please remember that Profile Optimization is different than Profile Guided Optimization, another features introduced in .net framework. Profile Guided optimization is about improving the layout of native libraries, not running on CLR, based on some test scenarios. Profile Optimization is about background [JIT]ing the application using mutlicore extra resources. On the other hand Profile Guided Optimization is a compiler optimization technique which improve the native image layout based on some test scenarios. It would definitely be better that compiler heuristic but it definitely wouldn't be based on the actual usage of the system which could be different than the selected test scenarios. Microsoft has included some extra tools in Visual Studio 2012 to make the guided optimization better including MPGO [Managed Profile Guided Optimization] tool.

[Note] This is enabled by default for ASP.net 4.5 and Silverlight 5 applications.



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