.NET GENES

When working with Dropdownlists in ASP.NET MVC, I encountered an error as stated in the title of this post when casting an int variable through LINQ Select() statement. List<SelectListItem> itemCountries = new List<SelectListItem>(); itemCountries.AddRange(( from country in _context.CascadeCountries select country) .Select(x => new SelectListItem { Value = x.CountryID.ToString(), //error here... Text = x.CountryName }).ToList()); After doing some research, I found out that the statement returned by the Select statement above is IQueryable and the itemCountries variable is an IEnumerable . So, the fix for this issue is to cast the LINQ statement with AsEnumerable() and then followed by the Select() statement which sets the values for the SelectListItems properties. List<SelectListItem> itemCountries = new List<SelectListItem>(); itemCountries.AddRange(( from country in _context.Casca

I have this old T-SQL script that retrieves previous row value of a certain order year which uses a combination of derived tables, left join and group by to achieve the desired result. Upon visiting this script and doing some research on new T-SQL functions, I encountered an article from SQL Authority on How To Access Previous Row and Next Row in Select statement . So, given the time I quickly converted my script using Lag() function and was surprised to see that my new script looks clean and orderly compared to the old one. Old T-SQL Script SELECT Curr_Data.Year_Order, Curr_Data.Customer_Count AS Customer_Count, Prev_Data.Customer_Count AS Previous_Customer_Count, Curr_Data.Customer_Count - Prev_Data.Customer_Count AS Growth FROM ( SELECT YEAR (Orderdate) AS Year_Order, COUNT ( DISTINCT CustomerID) AS Customer_Count FROM CustomerOrders GROUP BY YEAR (Orderdate)) AS Curr_Data LEFT OUTER JOIN ( SELECT YEAR (Orderdate) A

To escape curly braces in String.Format(), you have to prepend "{" symbol in the opening brace and append "}" in the closing brace as shown below. Code: string firstName = "Michael" ; string lastName = "Jordan" ; string output = String.Format( "Your name is: {{ {0}, {1} }}" , firstName, lastName); Console.WriteLine(output); Output:

In a scenario wherein you need to attach a single event like CheckedChanged() to a control array such as CheckBox controls, the common way to do it is using for each or for loop. Another way to achieve it is using LINQ's ForEach() method as demonstrated below. Event Code 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 void CheckBoxGeneric_CheckedChanged ( object sender, EventArgs e) { var checkBox = (CheckBox)sender; if (checkBox.Name == "chkBurger" ) { //... } else if (checkBox.Name == "chkSoda" ) { //... } else { //... } } Attach the event to the control array 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 private CheckBox[] OrderItems; OrderItems = new CheckBox[] { chkBurger, chkSoda, chkIceCream }; private void Form1_Load ( object sender, EventArgs e) { //solution 1 using foreach loop //foreach (var checkControl in OrderItems) //{ // checkControl.CheckedChanged += new EventHandler(CheckBoxGeneric_CheckedChanged);

Hello and Good Evening When working with a WebBrowser to extract information from a webpage, the most common classes that are probably used to traverse or navigate it's DOM are from the System.Windows.Forms namespace such as HtmlDocument, HtmlElementCollection and etc. Another way to navigate and traverse the DOM of the WebBrowser's HTMLDocument is using the Microsoft.mshtml namespace which contains interfaces for the rendering engine of Internet Explorer. So to access those interfaces and in your application, add reference to Microsoft.mshtml. In the code sample below, set alias for the Microsoft.mshtml namespace. You need to explicitly specify the namespace of a class or interface as MSHTML since Windows.Forms also have same class names with the former. And one thing to remember is that, empty results in mshtml does not yield nulls. Instead, it produces DBNull value. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 using MSHTML = mshtml; //set namespace alia

When working with DBNull values in VB.NET you can check if that object is of type DBNull using IsDBNull(object) . So, to do this in C#, I have two options to do this. The first one is to get the type of that object and compare it with typeof(System.DBNull). Code 1 2 3 4 5 var attribute = element.getAttribute( "data-mixvids" ); if (attribute.GetType() != typeof (System.DBNull)) { lstElementVids.Add(element.getAttribute( "data-mixvids" )); } The other one is presented in MSDN docs using DBNull.Value.Equals(object) which returns true. Code 1 2 3 4 5 var attribute = element.getAttribute( "data-mixvids" ); if (!System.DBNull.Value.Equals(attribute)) { lstElementVids.Add(element.getAttribute( "data-mixvids" )); } Reference: MSDN Convert.IsDBNull Method (Object)

Given in a webpage there are several input elements and you want to fire the click event of an input element of type submit, here's how to do it using the Webbrowser control. C# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 HtmlElementCollection htmlElementCollection = new HtmlElementCollection(); if (WebBrowser1.Document != null ) { htmlElementCollection = WebBrowser1.Document.GetElementsByTagName( "input" ); if (htmlElementCollection != null && htmlElementCollection.Count > 0) { foreach (HtmlElement element in htmlElementCollection) { if (element.GetAttribute( "value" ).Equals( "Submit" )) { element.InvokeMember( "click" ); } } } } VB.NET 1 2 3 4 5 6 7 8 9 10 11 12 13 Dim htmlElementCollection As HtmlElementCollection If (WebBrowser1.Document IsNot Nothing ) Then With WebBrowser1.Document htmlElem

Here's how to extract url(s) from a string or document using Regex.Matches() method. The Regex.Matches() method returns an array object MatchCollection in which you can access individual elements using it's index. Code: 1 2 3 4 5 6 7 8 9 10 11 12 string pattern = "(http|ftp|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+([\\w\\-\\.,@?^=%&amp;:/~\\+#]*[\\w\\-\\@?^=%&amp;/~\\+#])?" ; string Input = "<<abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ\"abcd\" href=\"https://mediatemple.net\"" + "Sample text for testing>http://regexr.com/foo.html?q=bar>" ; string url1 = string .Empty; string url2 = string .Empty; if (Regex.Matches(Input, pattern).Count > 0) { MatchCollection matches = Regex.Matches(Input, pattern); url1 = matches[0].Value; url2 = matches[1].Value; }

The CookieContainer class does not contain a method that clears or removes the cookies associated with it. To remove them, you have to set each cookie's Expired property to True as shown below. C# 1 2 3 4 var cookies = cookieContainer.GetCookies( new Uri( "http://your_url_example_here" )); foreach (Cookie co in cookies) { co.Expired = true ; } VB.NET 1 2 3 4 Dim cookies = cookieContainer.GetCookies( New Uri( "http://your_url_example_here" )) For Each co As Cookie In cookies co.Expired = True Next

Here's a solution using LINQ that will retrieve all folders inside a specific directory in order of creation time. C# 1 2 3 4 5 6 7 8 9 10 11 12 string path = @"C:\" ; if (Directory.Exists(path)) { DirectoryInfo dir = new DirectoryInfo(path); DirectoryInfo[] directories = dir.GetDirectories(). OrderByDescending(p => p.CreationTime). ToArray(); if (directories.Length > 0) { foreach (DirectoryInfo directory in directories) { ListBox1.Items.Add(directory.Name); } } } VB.NET 1 2 3 4 5 6 7 8 9 10 11 12 Dim path As String = "C:\" If Directory.Exists(path) Then Dim dir As New DirectoryInfo(path) Dim directories As DirectoryInfo() = dir.GetDirectories(). OrderByDescending(Function(p) p.CreationTime). ToArray()