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European ASP.NET Core 3 Hosting - HostForLIFE.eu :: ASP.NET Core Denial of Service Vulnerability

clock October 22, 2019 12:09 by author Peter

In this blog, we are going to discuss vulnerable versions of .Net Core. Microsoft releases the information about security breaches in ASP.Net Core. It informs developers which version they need to update to remove this vulnerability. Microsoft is aware of DOS Attack in the OData library. If you are using OData library in your application in the sense attacker can exploit.

We have two types of dependencies in .net core,

  • Direct dependencies
  • transitive dependencies

Direct dependencies are dependencies where you specifically add a package to your project, transitive dependencies occur when you add a package to your project that in turn relies on another package.

Mitigation policy
Open your application through visual studio and go to package manager console and run the below command.
command :-  dotnet --info 

By running the above command you will come to know which package we need to update as per Microsoft security guidelines.
 
Direct dependencies
By editing your Cs.proj file we can fix the issue or we can update Nuget Package manager.
 
Transitive dependencies
Transitive dependencies occur when any vulnerable package is referring or relies on another package. By examining the project.asset.json file you can fix the issue.

In this blog, we have discussed vulnerable versions of .Net Core. As per Microsoft security advice it is better to update packages which are in your application.



European ASP.NET Core Hosting :: Paging Using Repeater Control In ASP.NET With And Without Stored Procedure

clock October 16, 2019 11:06 by author Peter

By default, pagination is not enabled in a Repeater control. We have to write custom pager control to use paging in a Repeater control. Here, I will explain how to implement paging in Repeater control in ASP.NET with and without a stored procedure. I am using Visual Studio 2019 to create the application.

Step 1
First, we have to create a table “tblCustomers” to test the paging in the repeater control.
CREATE TABLE [dbo].[tblCustomers]( 
[Id] [int] NOT NULL, 
[Name] [nvarchar](50) NULL, 
[Company] [nvarchar](50) NULL, 
[Phone] [nvarchar](50) NULL, 
[Address] [nvarchar](50) NULL, 
[Country] [nvarchar](50) NULL, 
[Email] [nvarchar](50) NULL 


After creating the table, add some record to the table.

Step 2
Open Visual Studio and click on "Create a new project".
Select ASP.NET Web Application from templates and click on “Next”.
Then, give the project name as “AspRepeater” and then click “Create”.
Now, choose “Web Forms” from the template and click on “Create”.

ASP.NET Repeater Control without Stored Procedure

Step 3
Now, create a new weborm “RepeaterControl” and write the code following code in your “RepeaterControl.aspx” page.
Code for RepeaterControl.aspx page.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="RepeaterControl.aspx.cs" Inherits=" AspRepeater.RepeaterControl" %> 

<!DOCTYPE html> 

<html xmlns="http://www.w3.org/1999/xhtml"> 
<head runat="server"> 
<title>Repeater Control without Stored Procedure</title> 
</head> 
<body> 
<form id="form1" runat="server"> 
    <div> 
        <asp:Repeater ID="Repeater2" runat="server"> 
            <HeaderTemplate> 
                <table id="tbDetails" style="width: 100%; border-collapse: collapse;" border="1" cellpadding="5" cellspacing="0"> 
                    <tr style="background-color: lightgray; height: 30px; color: black; text-align: center"> 
                        <th>Id</th> 
                        <th>Customer Name</th> 
                        <th>Company Name</th> 
                        <th>Phone</th> 
                        <th>Address</th> 
                        <th>E-Mail</th> 
                    </tr> 
            </HeaderTemplate> 
            <ItemTemplate> 
                <tr style="height: 25px;"> 
                    <td> 
                        <%#Eval("Id").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Name").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Company").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Phone").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Address").ToString()%>, <%#Eval("Country").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Email").ToString()%> 
                    </td>                         
                </tr> 
            </ItemTemplate> 
            <FooterTemplate> 
                </table> 
            </FooterTemplate> 
        </asp:Repeater> 
    </div> 
    <br /> 
    <div style="text-align:center"> 
        <asp:Repeater ID="Repeater1" runat="server" OnItemCommand="Repeater1_ItemCommand"> 
            <ItemTemplate> 
                <asp:LinkButton ID="lnkPage" 
                    Style="padding: 8px; margin: 2px; background: lightgray; border: solid 1px #666; color: black; font-weight: bold" 
                    CommandName="Page" CommandArgument="<%# Container.DataItem %>" runat="server" Font-Bold="True"><%# Container.DataItem %> 
                </asp:LinkButton> 
            </ItemTemplate> 
        </asp:Repeater> 
    </div> 
</form> 
</body> 
</html> 


Code for RepeaterControl.aspx.cs,
using System; 
using System.Collections; 
using System.Configuration; 
using System.Data; 
using System.Data.SqlClient; 
using System.Web.UI.WebControls; 

namespace AspRepeater 

public partial class RepeaterControl : System.Web.UI.Page 
{  
    private int iPageSize = 15; 

    protected void Page_Load(object sender, EventArgs e) 
    { 
        if (!IsPostBack) 
        { 
            GetCustomers(); 
        } 
    } 

    private void GetCustomers() 
    { 
        DataTable dtData = new DataTable(); 
        string conString = ConfigurationManager.ConnectionStrings["dbConnection"].ConnectionString; 
        SqlConnection sqlCon = new SqlConnection(conString); 
        sqlCon.Open(); 
        SqlCommand sqlCmd = new SqlCommand("Select * From tblCustomers", sqlCon); 
        SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd); 
        sqlDa.Fill(dtData); 
        sqlCon.Close(); 

        PagedDataSource pdsData = new PagedDataSource(); 
        DataView dv = new DataView(dtData); 
        pdsData.DataSource = dv; 
        pdsData.AllowPaging = true; 
        pdsData.PageSize = iPageSize; 
        if (ViewState["PageNumber"] != null) 
            pdsData.CurrentPageIndex = Convert.ToInt32(ViewState["PageNumber"]); 
        else 
            pdsData.CurrentPageIndex = 0; 
        if (pdsData.PageCount > 1) 
        { 
            Repeater1.Visible = true; 
            ArrayList alPages = new ArrayList(); 
            for (int i = 1; i <= pdsData.PageCount; i++) 
                alPages.Add((i).ToString()); 
            Repeater1.DataSource = alPages; 
            Repeater1.DataBind(); 
        } 
        else 
        { 
            Repeater1.Visible = false; 
        } 
        Repeater2.DataSource = pdsData; 
        Repeater2.DataBind(); 
    } 
     
    protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e) 
    { 
        ViewState["PageNumber"] = Convert.ToInt32(e.CommandArgument); 
        GetCustomers(); 
    } 



ASP.NET Repeater Control with Stored Procedure

Step 4
By using a Stored Procedure, we can fetch only one-page records from the available records based on the page index. For example, if our table has 300 records and we need to display only 15 records per page, then we will fetch only 15 records based on the page index.

Script for the Stored Procedure,
CREATE PROCEDURE GetCustomer 
@PageIndex INT = 1, 
@PageSize INT = 15, 
@RecordCount INT OUTPUT 
AS 
BEGIN 
SET NOCOUNT ON; 
SELECT ROW_NUMBER() OVER(ORDER BY Id ASC)AS RowNumber,ID, 
Name,Company,Phone,Address,Country,Email 
INTO #Results FROM tblCustomers 
  
SELECT @RecordCount = COUNT(*) FROM #Results 
        
SELECT * FROM #Results WHERE RowNumber BETWEEN(@PageIndex -1) * @PageSize + 1  
AND (((@PageIndex -1) * @PageSize + 1) + @PageSize) - 1 
  
DROP TABLE #Results 
END 

Step 5
Now, create a new webform “RepeaterControl1” and write the following code in your “RepeaterControl1.aspx” page.

Code for RepeaterControl.aspx page.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="RepeaterControl1.aspx.cs" Inherits="AspRepeater.RepeaterControl1" %> 

<!DOCTYPE html> 

<html xmlns="http://www.w3.org/1999/xhtml"> 
<head runat="server"> 
<title>Repeater Control with Stored Procedure</title> 
</head> 
<body> 
<form id="form1" runat="server"> 
    <div> 
        <asp:Repeater ID="Repeater1" runat="server"> 
            <HeaderTemplate> 
                <table id="tbDetails" style="width: 100%; border-collapse: collapse;" border="1" cellpadding="5" cellspacing="0"> 
                    <tr style="background-color: lightgray; height: 30px; color: black; text-align: center"> 
                        <th>Id</th> 
                        <th>Customer Name</th> 
                        <th>Company Name</th> 
                        <th>Phone</th> 
                        <th>Address</th> 
                        <th>E-Mail</th> 
                    </tr> 
            </HeaderTemplate> 
            <ItemTemplate> 
                <tr style="height: 25px;"> 
                    <td> 
                        <%#Eval("Id").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Name").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Company").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Phone").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Address").ToString()%>, <%#Eval("Country").ToString()%> 
                    </td> 
                    <td> 
                        <%#Eval("Email").ToString()%> 
                    </td> 
                </tr> 
            </ItemTemplate> 
            <FooterTemplate> 
                </table> 
            </FooterTemplate> 
        </asp:Repeater> 
    </div> 
    <br /> 
    <div style="text-align:center"> 
        <asp:Repeater ID="Repeater2" runat="server" OnItemCommand="Repeater2_ItemCommand"> 
            <ItemTemplate> 
                <asp:LinkButton ID="lnkPage" 
                    Style="padding: 8px; margin: 2px; background: lightgray; border: solid 1px #666; color: black; font-weight: bold" 
                    CommandName="Page" CommandArgument="<%# Container.DataItem %>" runat="server" Font-Bold="True"><%# Container.DataItem %> 
                </asp:LinkButton> 
            </ItemTemplate> 
        </asp:Repeater> 
    </div> 
</form> 
</body> 
</html> 

Code for RepeaterControl1.aspx.cs.
using System; 
using System.Collections.Generic; 
using System.Configuration; 
using System.Data; 
using System.Data.SqlClient; 
using System.Web.UI.WebControls; 

namespace AspRepeater 

public partial class RepeaterControl1 : System.Web.UI.Page 

    private int iPageSize = 15; 
    protected void Page_Load(object sender, EventArgs e) 
    { 
        if (!IsPostBack) 
        { 
            this.GetCustomers(1); 
        } 
    } 

    private void GetCustomers(int iPageIndex) 
    { 
        string conString = ConfigurationManager.ConnectionStrings["dbConnection"].ConnectionString; 
        SqlConnection sqlCon = new SqlConnection(conString); 
        sqlCon.Open(); 
        SqlCommand sqlCmd = new SqlCommand("GetCustomer", sqlCon); 
        sqlCmd.CommandType = CommandType.StoredProcedure; 
        sqlCmd.Parameters.AddWithValue("@PageIndex", iPageIndex); 
        sqlCmd.Parameters.AddWithValue("@PageSize", iPageSize); 
        sqlCmd.Parameters.Add("@RecordCount", SqlDbType.Int, 4); 
        sqlCmd.Parameters["@RecordCount"].Direction = ParameterDirection.Output; 
        IDataReader iDr = sqlCmd.ExecuteReader(); 
        Repeater1.DataSource = iDr; 
        Repeater1.DataBind(); 
        iDr.Close(); 
        sqlCon.Close(); 
        int iRecordCount = Convert.ToInt32(sqlCmd.Parameters["@RecordCount"].Value); 

        double dPageCount = (double)((decimal)iRecordCount / Convert.ToDecimal(iPageSize)); 
        int iPageCount = (int)Math.Ceiling(dPageCount); 
        List<ListItem> lPages = new List<ListItem>(); 
        if (iPageCount > 0) 
        { 
            for (int i = 1; i <= iPageCount; i++) 
                lPages.Add(new ListItem(i.ToString(), i.ToString(), i != iPageIndex)); 
        } 
        Repeater2.DataSource = lPages; 
        Repeater2.DataBind(); 
    } 

    protected void Repeater2_ItemCommand(object source, RepeaterCommandEventArgs e) 
    { 
        int iPageIndex = Convert.ToInt32(e.CommandArgument); 
        GetCustomers(iPageIndex); 
    } 

 



European ASP.NET Core Hosting :: TextBox Autocomplete with .NET Core 3.0

clock October 11, 2019 11:56 by author Peter

.NET Core 3.0 is the latest version of .NET Core and now supports WinForms and WPF. This sample shows how you can perform fill data to Autocomplete TextBox in another thread without slow down the main UI (User Interface). With this sample, you can do a better user experience for the end-user.

TextBox Autocomplete
Autocomplete helps the user to search/type from a know list. In my application, I build a list to Autocomplete with > 10.000 items and is very fast even on slow computers.

Autocomplete is an old feature, but this POST will demonstrate how to perform his use to load data fastly already in NET Core 3.0.

When you fill a Collection, if you have a huge suggestion list, this will make the UI (User Interface) freezes. But if you process in another thread the UI will not have any issues.

More technical information you can have here.

How it works

Like the other POST what uses a delegate, here, we use another thread to load data and delegate to bind the Autocomplete Collection in the current UI thread.
using System;  
using System.Data.SqlClient;  
using System.Drawing;  
using System.Windows.Forms;  
 
namespace TextBoxWithAutoComplete  
{  
 
    /// <summary>  
    /// 10-10-2019  
    /// </summary>  
    public partial class Form1 : Form  
    {  
 
        private TextBox textBox1;  
        public Form1()  
        {  
            InitializeComponent();  
 
            textBox1 = new TextBox  
            {  
                Location = new Point(0, 0),  
                Size = new Size(100, 32),  
                Visible = true,  
                TabIndex = 0  
            };  
            Controls.Add(textBox1);  
 
            Load += Form1_Load;  
        }  
 
        public void Form1_Load(object sender, EventArgs e)  
        {  
            Show(); // You need to show the form to avoid a thread error  
 
            LoadData(); // Start to load Data  
        }  
 
        private SqlConnection GetConnection()  
        {  
            // Init your connection  
            var oCnn = new SqlConnection  
            {  
                ConnectionString = "YOUR_CONNECTION_STRING"  
            };  
            oCnn.Open();  
            return oCnn;  
        }  
 
 
        #region TreadSafeLoading  
        private delegate void UpdateUIDelegate(AutoCompleteStringCollection myCollection);  
 
        /// <summary>  
        /// Load Data - You can make public to load as you need  
        /// </summary>  
        private void LoadData()  
        => // Start this process in a new thread  
            new System.Threading.Thread(() => OutOfThreadProcess()).Start();  
        // You can start others, every one in a new thread!  
 
        /// <summary>  
        /// Start fill in another Thread  
        /// </summary>  
        private void OutOfThreadProcess()  
        {  
            // inialize the collection  
            var myCollection = new AutoCompleteStringCollection();  
            using var oCnn = GetConnection();  
 
            // Start your SQL Query  
            var cmd = new SqlCommand($"Select [FirstName] + ' ' + [LastName] as [contactName] From [AdventureWorks].[Person].[Contact] Order By [FirstName], [LastName]", oCnn);  
 
            // Read and fill the collection  
            using var reader = cmd.ExecuteReader();  
            while (reader.Read())  
                myCollection.Add(reader.GetString(0));  
 
            // Invoke in a UI thread  
            _ = Invoke(new UpdateUIDelegate(UpdateUIInvoke), myCollection);  
        }  
 
        /// <summary>  
        /// Current UI Thread threatment  
        /// </summary>  
        /// <param name="myCollection"></param>  
        private void UpdateUIInvoke(AutoCompleteStringCollection myCollection)  
        {  
            // Setup up in corrent UI Thread  
            textBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;  
            textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;  
            textBox1.AutoCompleteCustomSource = myCollection;  
#if (IS_TELERIK_RadTextBoxControl)  
            // If you use Telerik  
            // I found an issue in Telerik by Progress, without fix.  
            if (ParentForm != null)  
                ParentForm.FormClosing += new FormClosingEventHandler(UIFormClosing);  
#endif  
        }  
#if (IS_TELERIK_RadTextBoxControl)  
        private void UIFormClosing(object sender, FormClosingEventArgs e) => textBox1.AutoCompleteCustomSource = null;  
 
#endif  
        #endregion  
 
    }  
}  

Observation

When you use this technic may you receive errors if you run the new thread without fire the Show() method from the form, this occurs because the current window(form) hasn't the Handle initialized.

Conclusion
I design this technic when I upgrade to .NET Core 3 and develop a fix for the FileSystemWatcher event that fires in a new thread, so I took the same idea to make Autocomplete load collection works in a new thread.



ASP.NET 4.8 Hosting - HostForLIFE.eu :: Display SiteMap Links On ASP.NET Page

clock September 17, 2019 12:33 by author Peter

Create a sitemap sml based file and save it with sitemap.config name. Here is an example.
    <?xml version="1.0" encoding="utf-8" ?> 
    <siteMap> 
    <siteMapNode title="Home" controller="Home" action="Overview"> 
    <siteMapNode title="Dashboard" nopResource="Admin.Dashboard" controller="Home" action="Index" ImageUrl="~/Administration/Content/images/ico-dashboard.png" /> 
    <siteMapNode title="Catalog" nopResource="Admin.Catalog" PermissionNames="ManageCatalog" ImageUrl="~/Administration/Content/images/ico-catalog.png" > 
    <siteMapNode title="Categories" nopResource="Admin.Catalog.Categories"> 
    <siteMapNode title="List" nopResource="Admin.Common.List" controller="Category" action="List"/> 
    <siteMapNode title="Tree view" nopResource="Admin.Common.Treeview" controller="Category" action="Tree"/> 
    </siteMapNode> 
    </siteMap> 


If you're new to sitemap, learn here how to create a site map in Visual Studio.
 
To bind above sitemap and display on a page, please follow the below code example.
    @using System.Data; 
    @using System; 
    <div class="page-title"> 
    <h2>"Sitemap"</h2> 
    </div> 
    @{ 
    string fileName = System.Web.HttpContext.Current.Server.MapPath("~/sitemap.config"); 
    DataSet ds = new DataSet(); 
    ds.ReadXml(fileName); 
    <table> 
    <tr> 
    <td width="20%"></td> 
    <td style="border: 2px double #CCCCCC; padding-left: 50px;" width="30%"> 
    @for(int i=1;i<ds.Tables[0].Rows.Count/2;i++) 
    { 
    if(ds.Tables[0].Rows[i]["action"].ToString()=="") 
    { 
    <h4>@ds.Tables[0].Rows[i]["title"].ToString()</h4> 
    } 
    else 
    { 
    string url = "../" + @ds.Tables[0].Rows[i]["controller"].ToString() + "/" + @ds.Tables[0].Rows[i]["action"].ToString(); 
    <ul class="top-menu"><li><a href="@url" temp_href="@url">@ds.Tables[0].Rows[i]["title"].ToString()</a></li></ul> 
    } 
    } 
    </td> 
    <td style="border: 2px double #CCCCCC; padding-left: 50px;" width="30%"> 
    @for (int i = ds.Tables[0].Rows.Count / 2; i < ds.Tables[0].Rows.Count; i++) 
    { 
    if(ds.Tables[0].Rows[i]["action"].ToString()=="") 
    { 
    <h4>@ds.Tables[0].Rows[i]["title"].ToString()</h4> 
    } 
    else 
    { 
    string url = "../" + @ds.Tables[0].Rows[i]["controller"].ToString() + "/" + @ds.Tables[0].Rows[i]["action"].ToString(); 
    <ul class="top-menu"><li><a href="@url" temp_href="@url">@ds.Tables[0].Rows[i]["title"].ToString()</a></li></ul> 
    } 
    } 
    </td> 
    </tr> 
    </table> 
    } 


Run application and you'll see a page with sitemap links.

HostForLIFE.eu ASP.NET 4.8 Hosting

European best, cheap and reliable ASP.NET hosting with instant activation. HostForLIFE.eu is #1 Recommended Windows and ASP.NET hosting in European Continent. With 99.99% Uptime Guaranteed of Relibility, Stability and Performace. HostForLIFE.eu security team is constantly monitoring the entire network for unusual behaviour. We deliver hosting solution including Shared hosting, Cloud hosting, Reseller hosting, Dedicated Servers, and IT as Service for companies of all size.



ASP.NET 4.8 Hosting - HostForLIFE.eu :: Use Distinct And FirstOrDefault Clauses In .NET Using linq.js

clock September 10, 2019 12:37 by author Peter

In this version, I will tell you about using Let us see how to use Distinct() and FirstOrDefault() clauses with the help of linq.js in .NET Web Application. It's useful to write simple LINQ queries from Entityframework to client side with LinqJS.

It’s better for validating data at the client side.
Improves performance of the application.

Let’s see one by one,
Distinct() function is different here.

C#.NET Code
    var FirstNameCollection = myDataArray.Select(x => x.FirstName).Distinct(); 
LinqJS Code
    // Retrieves non-duplicate FirstName values. 
    var FirstNameCollection = Enumerable.From(myDataArray).Distinct(function(x) { 
        return x.FirstName; 
    }).Select(function(FName) { 
        return FName; 
    }).ToArray(); 
The FirstOrDefault() function is nearly similar.

C#.NET Code
    public class cmbMonthOfWeek { 
        public string cmbMonth { 
            get; 
            set; 
        } 
        public int Id { 
            get; 
            set; 
        } 
    } 
    List < cmbMonthOfWeek > weekInfo = new List < cmbMonthOfWeek > (); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "First week", Id = 0 
    }); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "Second week", Id = 1 
    }); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "Third week", Id = 2 
    }); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "Fourth week", Id = 3 
    }); 
    var defaultWeekData = (from p in weekInfo where p.Id == 1 select p).FirstOrDefault();
Note

Here in defaultWeekData, you will get cmbMonth = "Second week".

LinqJS Code
    $scope.cmbMonthOfWeek = [{ 
        "cmbMonth": "First week", 
        "Id": 0 
    }, { 
        "cmbMonth": "Second week", 
        "Id": 1 
    }, { 
        "cmbMonth": "Third week", 
        "Id": 2 
    }, { 
        "cmbMonth": "Fourth week", 
        "Id": 3 
    }, ]; 
    var defaultWeekData = Enumerable.From($scope.cmbMonthOfWeek).Where(function(x) { 
        return x.Id == 1 
    }).FirstOrDefault();  Distinct And FirstOrDefault Clauses In .NET Using linq.js

HostForLIFE.eu ASP.NET 4.8 Hosting

European best, cheap and reliable ASP.NET hosting with instant activation. HostForLIFE.eu is #1 Recommended Windows and ASP.NET hosting in European Continent. With 99.99% Uptime Guaranteed of Relibility, Stability and Performace. HostForLIFE.eu security team is constantly monitoring the entire network for unusual behaviour. We deliver hosting solution including Shared hosting, Cloud hosting, Reseller hosting, Dedicated Servers, and IT as Service for companies of all size.



ASP.NET Hosting HostForLIFE.eu :: Centralized Exception Handling Without Using Try Catch Block In .Net Core 2.2 Web API

clock September 3, 2019 12:00 by author Peter

Rather than writing try catch block for each method, throwing exceptions manually and handling them, here we will use the power of .Net Core middleware to handle the exceptions at one single place, so that when an exception occurs anywhere in the code, the appropriate action can be taken. We will use UseExceptionHandler extension method that will add a middleware to the pipeline, and it will catch exceptions, log them, reset the request path, and re-execute the request if response has not already started.

Developer can customize the response format as well.

To achive this in .NetCore 2.2, this code snippet is very simple and it's just a matter of adding a few lines in your Startup.cs.

Simply go in Configure method and add the below code,
if (env.IsDevelopment()) {  
    app.UseDeveloperExceptionPage();  
} else {  
    app.UseExceptionHandler(errorApp => errorApp.Run(async context => {  
        // use Exception handler path feature to catch the exception details   
        var exceptionHandlerPathFeature = context.Features.Get < IExceptionHandlerPathFeature > ();  
        // log errors using above exceptionHandlerPathFeature object   
        Console.WriteLine(exceptionHandlerPathFeature ? .Error);  
        // Write a custom response message to API Users   
        context.Response.StatusCode = "500";  
        // Set a response format    
        context.Response.ContentType = "application/json";  
        await context.Response.WriteAsync("Some error occured.");  
    }));  
}  


The Console.WriteLine() is for demonstration purposes only. Here a developer can log the exceptions using any tool/package getting used in their project.

When any exceptions are thrown in the application this code will be executed and will produce the desired custom response in non-development environments (as in a development env we are using UseDeveloperExceptionPage() as a middleware).

HostForLIFE.eu ASP.NET 4.8 Hosting
HostForLIFE.eu is European Windows Hosting Provider which focuses on Windows Platform only. We deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes. We have customers from around the globe, spread across every continent. We serve the hosting needs of the business and professional, government and nonprofit, entertainment and personal use market segments.

 



ASP.NET 4.8 Hosting HostForLIFE.eu :: Fix Error on System.Web.UI.ViewStateException

clock August 27, 2019 12:38 by author Peter

In this post, I will tell you about fix System.Web.UI.ViewStateException: Invalid viewstate or System.Web.HttpException: The client disconnected exception Response.IsClientConnected Property ASP.NET 4.8.What is HttpResponse.IsClientConnected Property: HttpResponse.IsClientConnected used to gets a quality demonstrating whether the customer is still joined with the server.

The accompanying illustration utilizes the IsClientConnected property to check whether the customer that is asking for the page remains connected to the server. IfIsClientConnected is genuine, the code calls the  Redirect  technique, and the client will see an alternate page. In the event that IsClientConnected is false, then the code calls the End system and all page handling is ended.

 

And here is code that I used:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Fix System.Web.UI.ViewStateException
    </title></head>
<body>
    <form id="form1" runat="server">
    <div>Welcome</div>
    </form>
</body>
</html>

C#
public partial class ClientDisconnected : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //Check whether the browser(client) remains connected to the server
        if (Response.IsClientConnected)
        {
            // if  browser connected, redirect to the Main.aspx page
            Response.Redirect("~/Main.aspx");
        }
        else
        {
            //if browser is not connected,terminate all response processing.
            Response.End();
        }
    }
}


VB.NET
Public Partial Class ClientDisconnected
    Inherits System.Web.UI.Page
    Protected Sub Page_Load(sender As Object, e As EventArgs)
        'Check whether the browser(client) remains connected to the server
        If Response.IsClientConnected Then
            ' if  browser connected, redirect to the Main.aspx page
            Response.Redirect("~/Main.aspx")
        Else
            'if browser is not connected,terminate all response processing.
            Response.[End]()
        End If
    End Sub
End Class

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European ASP.NET Core Hosting :: Rotate Ads Without Refreshing the Page Using AdRotator in ASP.NET

clock August 20, 2019 12:18 by author Peter

This article explains the concept of the AdRotator control without the user refreshing the page and rotates the ads on a certain time interval. This article also gives a tip to fetch ad information from an XML file. The AdRotator Control presents ad images each time a user enters or refreshes a webpage. When the ads are clicked, it will navigate to a new web location. However the ads are rotated only when the user refreshes the page. In this article, we will explore how you can easily rotate ads at regular intervals, without the user refreshing the page. First of all start Visual Studio .NET And make a new ASP.NET web site using Visual Studio 2010.
 
Now you have to create a web site.
Go to Visual Studio 2010
New-> Select a website application
Click OK

Now add a new page to the website.

    Go to the Solution Explorer
    Right-click on the Project name
    Select add new item
    Add new web page and give it a name
    Click OK

We create an images folder in the application which contains some images to rotate in the AdRotator control. Now add a XML file. To do so, right-click the App_Data folder > Add New Item > 'XML File' > Rename it to adXMLFile.xml and click Add. Put this code in the .XML File.

    <?xml version="1.0" encoding="utf-8" ?> 
    <Advertisements> 
    <Ad> 
    <ImageUrl>~/Images/image1.gif</ImageUrl> 
    <NavigateUrl>http://www.c-sharpcorner.com/</NavigateUrl> 
    <AlternateText>C-sharpcorner Home Page</AlternateText> 
    <Impressions>3</Impressions> 
    <Keyword>small</Keyword> 
    </Ad> 
    <Ad> 
    <ImageUrl>~/images/forest_wood.JPG</ImageUrl> 
    <NavigateUrl>http://www.c-sharpcorner.com/</NavigateUrl> 
    <AlternateText>C-sharpcorner Home Page</AlternateText> 
    <Impressions>2</Impressions> 
    <Keyword>small</Keyword> 
    </Ad> 
    <Ad> 
    <ImageUrl>~/images/image2.gif</ImageUrl> 
    <Width>300</Width> 
    <Height>50</Height> 
    <NavigateUrl>http://www.c-sharpcorner.com/</NavigateUrl> 
    <AlternateText>C-sharpcorner Home Page</AlternateText> 
    <Impressions>3</Impressions> 
    <Keyword>small</Keyword> 
    </Ad> 
    </Advertisements> 


XML file elements

  • Here is a list and a description of the <Ad> tag items.
  • ImageUrl - The URL of the image to display.
  • NavigateUrl - The URL where the page will go after AdRotator image is clicked.
  • AlternateText - Text to display if the image is unavailable.
  • Keyword - Category of the ad, which can be used to filter for specific ads.
  • Impressions - Frequency of ad to be displayed. This number is used when you want some ads to be displayed more frequently than others.
  • Height - Height of the ad in pixels.
  • Width - Width of the ad in pixel.

Now drag and drop an AdRotator control from the toolbox to the .aspx and bind it to the advertisement file. To bind the AdRotator to our XML file, we will make use of the "AdvertisementFile" property of the AdRotator control as shown below:
    <asp:AdRotator 
    id="AdRotator1" 
    AdvertisementFile="~/adXMLFile.xml" 
    KeywordFilter="small" 
    Runat="server" /> 


To rotate the ads without refreshing the page, we will add some AJAX code to the page.
    <Triggers> 
    <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" /> 
    </Triggers> 


The .aspx code will be as shown below.
 
Now drag and drop an UpdatePanel and add an AdRotator control into it. The DataList code looks like this:
    <%@ Page Language="C#" AutoEventWireup="true" CodeFile="adrotator.aspx.cs" Inherits="adrotator" %> 
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
    <html xmlns="http://www.w3.org/1999/xhtml"> 
    <head runat="server"> 
    <title></title> 
    </head> 
    <body> 
    <form id="form1" runat="server"> 
    <div> 
    <asp:ScriptManager ID="ScriptManager1" runat="server" /> 
    <asp:Timer ID="Timer1" Interval="1000" runat="server" /> 
    <asp:UpdatePanel ID="up1" runat="server"> 
    <Triggers> 
    <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" /> 
    </Triggers> 
    <ContentTemplate> 
    <asp:AdRotator ID="AdRotator1" AdvertisementFile="~/adXMLFile.xml" KeywordFilter="small" 
    runat="server" /> 
    </ContentTemplate> 
    </asp:UpdatePanel> 
    </div> 
    </form> 
    </body> 
    </html> 


Now run the application and test it. The AdRotator control rotates the ads without the user refreshing the page and rotates the ads on a certain time interval



European ASP.NET Core Hosting :: Session Wrapper Design Pattern For ASP.NET Core

clock August 14, 2019 11:11 by author Peter

In this article, we will learn to access the Session data in a Typed manner by getting IntelliSense support. We learned how to use Session in ASP.NET Core. In this article, we'll learn about Session Wrapper design pattern to ease the access of Session. In short, we'll make our access of session "Typed". Also, we may apply any validation or constraint in this wrapper class.

Step 1 - Create a Session Manager class

In this example, we are going to store two items in Session (i.e. ID & LoginName).
We are injecting IHttpContextAccessor so that we can access the Session variable.
We are creating properties which are actually accessing Session variable and returning the data or writing the data to Session.
We have added one helping property "IsLoggedIn" which is using other properties to make a decision. We may have more such helping/wrapper properties.
using Microsoft.AspNetCore.Http;

public class SessionManager 

    private readonly ISession _session; 
    private const String ID_KEY = "_ID"; 
    private const String LOGIN_KEY = "_LoginName"; 
    public SessionManager(IHttpContextAccessor httpContextAccessor) 
    { 
        _session = httpContextAccessor.HttpContext.Session; 
    } 

    public int ID 
    { 
        get 
        { 
            var v = _session.GetInt32(ID_KEY); 
            if (v.HasValue) 
                return v.Value; 
            else 
                return 0; 
        } 
        set 
        { 
            _session.SetInt32(ID_KEY, value); 
        } 
    } 
    public String LoginName 
    { 
        get 
        { 
            return _session.GetString(LOGIN_KEY); 
        } 
        set 
        { 
            _session.SetString(LOGIN_KEY, value); 
        } 
    } 
    public Boolean IsLoggedIn 
    { 
        get 
        { 
            if (ID > 0) 
                return true; 
            else 
                return false; 
        } 
    } 
}
 

Step 2
Registering IHttpContextAccessor and SessionManager in Startup file.
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>(); 
services.AddScoped<SessionManager>(); 


Step 3
Injecting SessionManager in your classes. Here is an example of Controller class but in the same way, it can be injected in non-controller classes too.
private readonly SessionManager _sessionManager; 
public HomeController(SessionManager sessionManager) 

  _sessionManager = sessionManager; 


Step 4
Using SessionManager to access Session Data,
_sessionManager.ID = 1; 
_sessionManager.LoginName = dto.Login; 

if(_sessionManager.IsLoggedIn == true) 

ViewBag.Login = _sessionManager.LoginName; 
return View(); 


Conclusion
This wrapper pattern helps using Session without worrying about KeyNames & Makes access easier. It also helps you apply different conditioning and constraints in a wrapper class.

 



ASP.NET 4.8 Hosting - HostForLIFE.eu :: How to Steps To Generate Excel Using EPPlus?

clock August 6, 2019 12:39 by author Peter

My work is to create an excel file, which will contain 3 fields: Address, Latitude and longitude.The user will upload an Address in an excel file and after reading the addresses from an excel file, I have to retrieve Latitude and longitude, using Bing MAP API and build another excel file, which can contain Addresses beside the Latitude and longitude of that address and download the new excel file to the user's end.

Create a MVC Application and add EPPLUS from NuGet package manager to your solution.

Now, Add the code to your .cshtml page.

<h2>Upload File</h2> 
 
sing (Html.BeginForm("Upload", "Home", null, FormMethod.Post, new { enctype = "multipart/form-data" })) 
  { 
      @Html.AntiForgeryToken() 
      @Html.ValidationSummary() 
 
      <div class="form-group"> 
          <input type="file" id="dataFile" name="upload" /> 
      </div> 
 
      <div class="form-group"> 
          <input type="submit" value="Upload" class="btn btn-default" /> 
      </div> 
 
       
  } 


And then, add the code, mentioned below to your controller.

[HttpPost] 
        public ActionResult Upload(HttpPostedFileBase upload) 
        { 
            if (ModelState.IsValid) 
            { 
                if (Path.GetExtension(upload.FileName) == ".xlsx") 
                { 
                    ExcelPackage package = new ExcelPackage(upload.InputStream); 
            //From This part we will read excel file 
                    DataTable dt = ExcelPackageExtensions.ToDataTable(package); 
 
 
                    DataTable dtExcel = new DataTable(); 
                    dtExcel.Columns.Add("Address", typeof(String)); 
                    dtExcel.Columns.Add("LAT", typeof(Double)); 
                    dtExcel.Columns.Add("LONG", typeof(Double)); 
 
                    List<Coordinates> lstCor = new List<Coordinates>(); 
                    for (int i = 0; i < dt.Rows.Count; i++) 
                    { 
                        //Fill the new data Table to generate new excel file 
                    } 
            //This method will generate new excel and download the same 
                    generateExcel(dtExcel);                  
                } 
            } 
            return View(); 
        } 


“ExcelPackageExtensions.ToDataTable(package)” for this create a new class with the name ExcelPackageExtensions and create a static method with the name “ToDataTable()”. The code is mentioned below.

public static class ExcelPackageExtensions 
    { 
        public static DataTable ToDataTable(this ExcelPackage package) 
        { 
            ExcelWorksheet workSheet = package.Workbook.Worksheets.First(); 
            DataTable table = new DataTable(); 
            foreach (var firstRowCell in workSheet.Cells[1, 1, 1, workSheet.Dimension.End.Column]) 
            { 
                table.Columns.Add(firstRowCell.Text); 
            } 
 
            for (var rowNumber = 2; rowNumber <= workSheet.Dimension.End.Row; rowNumber++) 
            { 
                var row = workSheet.Cells[rowNumber, 1, rowNumber, workSheet.Dimension.End.Column]; 
                var newRow = table.NewRow(); 
                foreach (var cell in row) 
                { 
                    newRow[cell.Start.Column - 1] = cell.Text; 
                } 
                table.Rows.Add(newRow); 
            } 
            return table; 
        } 
    } 

Now, add the code part to generate and download an Excel file.
[NonAction] 
        public void generateExcel(DataTable Dtvalue) 
        { 
            string excelpath = ""; 
            excelpath = @"C:\Excels\abc.xlsx";//Server.MapPath("~/UploadExcel/" + DateTime.UtcNow.Date.ToString() + ".xlsx"); 
            FileInfo finame = new FileInfo(excelpath); 
            if (System.IO.File.Exists(excelpath)) 
            { 
                System.IO.File.Delete(excelpath); 
            } 
            if (!System.IO.File.Exists(excelpath)) 
            { 
                ExcelPackage excel = new ExcelPackage(finame); 
                var sheetcreate = excel.Workbook.Worksheets.Add(DateTime.UtcNow.Date.ToString()); 
                if (Dtvalue.Rows.Count > 0) 
                { 
                    for (int i = 0; i < Dtvalue.Rows.Count; ) 
                    { 
                        sheetcreate.Cells[i + 1, 1].Value = Dtvalue.Rows[i][0].ToString(); 
                        sheetcreate.Cells[i + 1, 2].Value = Dtvalue.Rows[i][1].ToString(); 
                        sheetcreate.Cells[i + 1, 3].Value = Dtvalue.Rows[i][2].ToString(); 
                        i++; 
                    } 
                } 
                //sheetcreate.Cells[1, 1, 1, 25].Style.Font.Bold = true; 
                //excel.Save(); 
 
                var workSheet = excel.Workbook.Worksheets.Add("Sheet1"); 
                //workSheet.Cells[1, 1].LoadFromCollection(data, true); 
                using (var memoryStream = new MemoryStream()) 
                { 
                    Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"; 
                    Response.AddHeader("content-disposition", "attachment;  filename=Contact.xlsx"); 
                    excel.SaveAs(memoryStream); 
                    memoryStream.WriteTo(Response.OutputStream); 
                    Response.Flush(); 
                    Response.End(); 
                } 
            } 
 
        } 

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