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ASP.NET 4.5.1 France Hosting - HostForLIFE.eu :: How to restrict size of file upload in ASP.NET

clock February 10, 2014 06:49 by author Peter

I have one page that contains one file upload control to accept files from user and saving it in one folder. I have written code to upload file and saving it to folder it’s working fine after completion of my application my friend has tested my application like he uploaded large size file nearly 10 MB file at that time it’s shown the error page like “the page cannot displayed”. This topic contains only brief information about ASP.NET, if you're loooking for ASP.NET Hosting and want to be more familiar with ASP.NET, you should try HostForLIFE.eu.

Again I have search in net I found that file upload control allows maximum file size is 4MB for that reason if we upload file size larger than 4MB we will get error page like “the page cannot displayed” or “Maximum request length exceeded”. After that I tried to increase the size of uploaded file by setting some properties in web.config file like this:

 <system.web> 
 <httpRuntime executionTimeout="9999" maxRequestLength="2097151"/> 
 </system.web> 

Here httpRuntime means: Configures ASP.NET HTTP runtime settings. This section can be declared at the machine, site, application, and subdirectory levels.

executionTimeout means: Indicates the maximum number of seconds that a request is allowed to execute before being automatically shut down by ASP.NET.

maxRequestLength means: Indicates the maximum file upload size supported by ASP.NET. This limit can be used to prevent denial of service attacks caused by users posting large files to the server. The size specified is in kilobytes. The default is 4096 KB (4 MB).

After that write the following code in aspx page

 <html xmlns="http://www.w3.org/1999/xhtml"> 
 <head id="Head1" runat="server"> 
 <title>Untitled Page</title> 
 </head> 
 <body> 
 <form id="form1" runat="server"> 
 <div> 
 <asp:FileUpload ID="FileUpload1" runat="server" /> 
 <br /> 
 <asp:Button ID="btnUpload" runat="server" Text="Upload" onclick="btnUpload_Click" /> 
 <br /> 
 <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label> 
 </div> 
 </form> 
 </body> 
 </html> 
 After that write the following code in code behind 
 protected void btnUpload_Click(object sender, EventArgs e) 
 { 
 if (FileUpload1.HasFile) 
 { 
 if (FileUpload1.PostedFile.ContentLength < 20728650) 
 { 
 try 
 { 
 Label1.Text = "File name: " + 
 FileUpload1.PostedFile.FileName + "<br>" + 
 FileUpload1.PostedFile.ContentLength + " kb<br>" + 
 "Content type: " + 
 FileUpload1.PostedFile.ContentType; 
 } 
 catch (Exception ex) 
 { 
 Label1.Text = "ERROR: " + ex.Message.ToString(); 
 }  
 } 
 else 
 { 
 Label1.Text = "File size exceeds maximum limit 20 MB."; 
 } 
 } 
 } 


After that write the following code in web.config

 <system.web> 
 <httpRuntime executionTimeout="9999" maxRequestLength="2097151"/> 
 </system.web>



European ASP.NET 4.5 Hosting - Amsterdam :: Model Binding with Dropdown List in ASP.NET 4.5

clock December 20, 2013 05:32 by author Administrator

ASP.NET 4.5 Preview introduces new model binding for  ASP.NET web forms. The concept of model binding was first introduced with ASP.NET MVC and now it has incorporated with ASP.NET Web Forms. You can easily perform any CURD operation with any sort of data controls using any data access technology like Entity Framework,  ADO.NET, LINQ to SQL Etc.  In this post I am going talk about how you can bind the data with ASP.NET DropdownList using new Model Binding features.

Let’s say we have a speaker database and we wants to bind the name of the speakers with the DropDownList.  First placed an ASP.NET Dropdown control with the page  and set the “DataTextField” and “DataValueField” properties.

We can set the  ddlName.DataSource to specifying the data source from the code behind and bind the data with dropdpwnlist, but  in this case from the code behind to providing the data source.

Now, instead of specifying the DataSource, we will be setting the Dropdownlists SelectMethod property to point a method GetSpeakerNames() within the code-behind file.

Select method is expected to return us result of type IQueryable<TYPE>. Here is GetSpeakerName() method is defined as follows.

So, Instead of specifying the data source we are specifying the SelectMethod, which return the IQueryable type of Speaker object. Run the application, you will find the names binded with dropdown list. Hope this helps !



European ASP.NET Hosting Tips :: How to Consume Web API OData From .NET And JavaScript Client Applications

clock December 5, 2013 06:25 by author Scott

In this post, we will consume the service from a .NET client and a web page.

Consuming Web API OData using a .NET client:

A Web API OData service can be consumed using WCF Data Services client. If you gave already worked with WCF Data Services, you already know about consuming Web API OData Service as well.

Right click on a .NET project and choose the option Add Service Reference. In the dialog, enter the OData service URL and click the Go button.

The dialog parses the metadata received from the server and shows the available entities under container as shown in the screenshot. As we created just one entity in the service, we see the entity Employee alone. Name the namespace as you wish and hit OK. Visual Studio generates some classes for the client application based on the metadata.

The generated code contains the following:

  • A Container class, which is responsible for communicating with the service. It holds DataServiceQuery<TEntity> type properties for each EntitySet on the server
  • A class for every entity type. This class contains all properties mapped on the server, information about key of the entity

A Container is much like a DbContext in Entity Framework. It handles all the operations. Container is responsible for building OData URLs and sending requests to the service for any operation that client asks for. Let’s start by creating a Container. Constructor of the container accepts a URI, which is base address of the Web API OData service.

Container container = new Container(new Uri("http://localhost:1908/odata"));

To fetch details of all employees, we need to invoke the Corresponding DataServiceQuery property.

var employees = container.Employees;

Although the statement looks like an in-memory operation, it generates the corresponding URL internally and calls the server. Similarly, to get details of an employee with a given Id, we can write a LINQ query as shown:

var employee = container.Employees.Where(e => e.Id == 3).FirstOrDefault();

The above query makes a call to the Get method accepting key in the Web API Controller.

To create a new employee, we need to create an object of the Employee class, add it and ask Container to save it. Following snippet demonstrates this:

Employee emp = new Employee() { Id = 0, Name = "Hari", Salary = 10000 };
container.AddToEmployees(emp);
container.SaveChanges();

Performing update is also much similar. The difference is with calling the SaveChanges method.

emp = container.Employees.Where(e => e.Id == 3).FirstOrDefault();
emp.Name = "Stacy";
container.UpdateObject(emp);
container.SaveChanges(SaveChangesOptions.ReplaceOnUpdate);

If SaveChanges is called with SaveChangesOptions.ReplaceOnUpdate, it performs PUT operation on the resource. If SaveChangesOptions.PatchOnUpdate is passed, it performs PATCH operation on the resource.

To delete an entry, we need to pass an object to DeleteObject method and just like earlier cases; we need to call the SaveChanges method on the Container.

container.DeleteObject(container.Employees.Where(e => e.Id == 3).FirstOrDefault());
container.SaveChanges();

Consuming Web API OData using JavaScript client:

To consume the Web API OData service from a web page, the service has to be called using AJAX. The client can send an AJAX request to the URL of the OData service by specifying an HTTP verb to operate on the resource. To make our life easier, let’s use jQuery for AJAX calls.

To get details of all employees, we need to send a GET request to the OData URL. Values of entries in the collection are stored in a property named value in the object received as response. Fetching details of an employee with a given Id also follows similar approach. Following snippet demonstrates this:

$.getJSON(“/odata/Employees”, function(data){
    $.each(data.value, function(){
        //Modify UI accordingly
    });
}); 

$.getJSON(“/odata/Employees(3)”, function(data){
        //Modify UI accordingly
});

To add a new employee, we need to send the new object to $.post along with the URL.

var employee = {
    "Id": 0,
    "Name": “Ravi”,
    "Salary": 10000
}; 

$.post(“/odata/Employees”, employee).done(function(data){
    //Modify UI accordingly
});

Unfortunately, jQuery doesn’t have a shorthand method for PUT. But it is quite easy with $.ajax as well. To perform PUT on the resource, the request should be sent to the specific address with an ID and the modified object should be passed with the request.

var employee = {
    "Id": 3,
    "Name": “Ravi”,
    "Salary": 10000
}; 

$.ajax({
url: "/odata/Employees(" + employee.Id + ")",
       type: "PUT",
       data: employee
});

Building request for DELETE is similar to put, we just don’t need to pass the object.

$.ajax({
url: "/odata/Employees(" + id + ")",
type: "DELETE"
});



European ASP.NET Hosting - Amsterdam :: Tips to Send Email in ASP.NET 2.0 with Authentication

clock September 12, 2013 11:07 by author Scott

This is simple code how to send email in ASP.NET 2 with Authentication. In the following tutorial, I will show you how you can authenticate smtp client when sending emails in ASP.NET 2.0.

You need to import System.Net.Mail and System.Net namespaces to test following code.

C#

string mailFrom = "FromEmailAddressHere";
string mailTo = "ToEmailAddressHere";

string subject = "ASP.NET Test Email";


string messageBody = "This email is send to you from ASP.NET";

//  Create Mail Message Object
MailMessage message = new MailMessage(mailFrom, mailTo, subject, messageBody);

// Create SmtpClient class to Send Message
SmtpClient client = new SmtpClient();

// Here you specify your smtp host address such as smtp.myserver.com
client.Host = "localhost";

// Specify that you dont want to use default credentials
client.UseDefaultCredentials = false;

// Create user credentials by using NetworkCredential class


NetworkCredential credential = new NetworkCredential();
credential.UserName = "waqas";
credential.Password = "secret";
client.Credentials = credential;
client.Send(message);

VB.NET

Dim mailFrom As String = "FromEmailAddressHere"
Dim mailTo As String = "ToEmailAddressHere"

Dim subject As String = "ASP.NET Test Email"

Dim messageBody As String = "This email is send to you from ASP.NET"


' Create Mail Message Object
Dim message As New MailMessage(mailFrom, mailTo, subject, messageBody)


' Create SmtpClient class to Send Message
Dim client As New SmtpClient()


' Here you specify your smtp host address such as smtp.myserver.com
client.Host = "localhost"


' Specify that you dont want to use default credentials
client.UseDefaultCredentials = False


' Create user credentials by using NetworkCredential class

Dim credential As New NetworkCredential()
credential.UserName = "waqas"
credential.Password = "secret"
client.Credentials = credential

client.Send(message)

 



European ASP.NET Hosting - Amsterdam :: Tips Using FileUpload Control to Upload Your FIle

clock September 2, 2013 08:48 by author Scott

OK, I will talk again about FileUpload Control. Last week I have discussed about how to fix FileUpload Control that not work in Update Panel. FileUpload Control really help us to accepting file uploads from users. It is very easy now. Please see the example below. However, please notice that there are security concerns to to consider when accepting files from users! Here is the markup required:

<form id="form1" runat="server">
    <asp:FileUpload id="FileUploadControl" runat="server" />
    <asp:Button runat="server" id="UploadButton" text="Upload" onclick="UploadButton_Click" />
    <br /><br />
    <asp:Label runat="server" id="StatusLabel" text="Upload status: " />
</form>

And here is the CodeBehind code required to handle the upload:

protected void UploadButton_Click(object sender, EventArgs e)
{
   
if(FileUploadControl.HasFile)
    {
       
try
        {
           
string filename = Path.GetFileName(FileUploadControl.FileName);
            FileUploadControl.SaveAs(Server.MapPath(
"~/") + filename);
            StatusLabel.Text
= "Upload status: File uploaded!";
        }
       
catch(Exception ex)
        {
            StatusLabel.Text
= "Upload status: The file could not be uploaded. The following error occured: " + ex.Message;
        }
    }
}

As you can see, it's all relatively simple. Once the UploadButton is clicked, we check to see if a file has been specified in the upload control. If it has, we use the FileUpload controls SaveAs method to save the file. We use the root of our project (we use the MapPath method to get this) as well as the name part of the path which the user specified. If everything goes okay, we notify the user by setting the Text property of the StatusLabel - if not, an exception will be thrown, and we notify the user as well.

This example will get the job done, but as you can see, nothing is checked. The user can upload any kind of file, and the size of the file is only limited by the server configuration. A more robust example could look like this:

protected void UploadButton_Click(object sender, EventArgs e)
{
   
if(FileUploadControl.HasFile)
    {
       
try
        {
           
if(FileUploadControl.PostedFile.ContentType == "image/jpeg")
            {
               
if(FileUploadControl.PostedFile.ContentLength < 102400)
                {
                   
string filename = Path.GetFileName(FileUploadControl.FileName);
                    FileUploadControl.SaveAs(Server.MapPath(
"~/") +
filename);
                    StatusLabel.Text
= "Upload status: File uploaded!";
                }
               
else
                    StatusLabel.Text
= "Upload status: The file has to be less than 100 kb!";
            }
           
else
                StatusLabel.Text
= "Upload status: Only JPEG files are accepted!";
        }
       
catch(Exception ex)
        {
            StatusLabel.Text
= "Upload status: The file could not be uploaded. The following error occured: " + ex.Message;
        }
    }
}

Here we use the two properties, ContentLength and ContentType, to do some basic checking of the file which the user is trying to upload. The status messages should clearly indicate what they are all about, and you can change them to fit your needs.



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



European ASP.NET Hosting - Amsterdam :: Tips to Populate Or Bind DropDownList With JQuery And XML In Asp.Net

clock July 8, 2013 11:32 by author Scott

In this example i'm explaining How To Populate Or Bind DropDownList With JQuery And XML In Asp.Net.

Add jquery library reference in head section and place one dropdown on the page.

Add one list item with select as it's value.

   1:  <asp:DropDownList ID="DropDownList1" runat="server">
   2:  <asp:ListItem>Select</asp:ListItem>
   3:  </asp:DropDownList>
   4:   
   5:  <asp:Label ID="Label1" runat="server" Text=""/>


Following is the Cities.xml file i'm using to bind dropdownlist using jquery.

01<!--?xml version="1.0" encoding="utf-8" ?-->
02<cities>
03  <city>
04    <name>New York</name>
05    <id>1</id>
06  </city>
07    <city>
08    <name>Washington</name>
09      <id>2</id>
10  </city>
11  <city>
12    <name>Chicago</name>
13    <id>3</id>
14  </city>
15  <city>
16    <name>Seattle</name>
17    <id>4</id>
18  </city>
19</cities>

Add this script in head section of page.

01<script src="jquery-1.7.2.min.js" type="text/javascript"></script>  
02<script type="text/javascript">
03$(document).ready(function()
04{
05  $.ajax(
06  {
07    type: "GET",
08    url: "Cities.xml",
09    dataType: "xml",
10    success: function(xml)
11    {
12      var dropDown = $('#<%=DropDownList1.ClientID %>');
13      $(xml).find('City').each(function()
14      {
15        var name = $(this).find('name').text();
16        var id = $(this).find('id').text();
17        dropDown.append($("<option></option>").val(id).html(name));
18      });
19      dropDown.children(":first").text("--Select--").attr("selected", true);
20    }
21  });
22  $('#<%=DropDownList1.ClientID %>').change(function()
23  {
24  var ddl = $('#<%=DropDownList1.ClientID %>');
25  var selectedText = $('#<%=DropDownList1.ClientID %> option:selected').text();
26  var selectedValue = $('#<%=DropDownList1.ClientID %>').val();
27  document.getElementById('Label1').innerHTML = "You selected " + selectedText + " With id " + selectedValue;
28  });
29});
30</script>

Build and run the code.

 



About HostForLIFE.eu

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