Regex Email validation in c# dot net core

 Use this regex

/^_?[a-zA-Z0-9]([a-zA-Z0-9]*[._+-])*[a-zA-Z0-9_]+@(?!-)[A-Za-z0-9-]{1,63}(?<!-)(\.(?!-)[A-Za-z0-9-]{1,63}(?<!-))*\.[A-Za-z]{2,}$/

Works like examples shows below:

Regex obfuscate email

 Use this code in C# to obfuscate email using regex

// Online C# Editor for free

// Write, Edit and Run your C# code using C# Online Compiler

using System;

using System.Text.RegularExpressions;

public class HelloWorld

{

    public static void Main(string[] args)

    {

        Console.WriteLine ("Try programiz.pro");

        string _PATTERN = @"(?<=.{4}).(?=[^@]*?@)|(?:(?<=@.)|(?!^)\G(?=[^@]*$))(.)(?=.*\.)[a-zA-Z0-9]";

 

        string s = "john.travolta12+-3878787@gmail.com";

      string replacement = "*";

      

      if (!s.Contains("@"))

        Console.WriteLine( new String('*', s.Length));

      if (s.Split('@')[0].Length < 4) 

        Console.WriteLine( @"*@*.*"); 

        string result = Regex.Replace(s, _PATTERN, replacement);

      Console.WriteLine(result);

    

    }

}

c# httpclient The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch

 If we get this error while trying to get http reponse using HttpClient object, it could mean that certificate validation fails for the remote server. In this case we could get around the issue by overriding certification validation logic like so:

var handler = new HttpClientHandler

 {

     ClientCertificateOptions = ClientCertificateOption.Manual,

     ServerCertificateCustomValidationCallback = (httpRequestMessage, cert, cetChain, policyErrors) => true

 };

 handler.AllowAutoRedirect = false;

       

 handler.ServerCertificateCustomValidationCallback = (cert, chain, erros, flag)=> { return true; };

 var apiClient = new HttpClient(handler);

 apiClient.SetBearerToken(tokenResponse.AccessToken);

 

 var response = apiClient.GetAsync(apiUrl).Result;

SSL Error - The connection for this site is not secure

 After cloning a git repo of dot net framework website and trying to run it all I could see was this error

Turns out the fix was to simply enable SSL in F4 properties windows and default website start url to SSL url

Secure micro services using jwt and ocelot

 Secure Microservices Using JWT With Ocelot in .NET Core (code-maze.com)

C# generic type converter

 Here is a way to create a generic type converter in c#

c# - How to Convert a String to a Nullable Type Which is Determined at Runtime? - Stack Overflow

Share cookies between dot net framework and dot net core

Since dot net framework encryption is different from that of dot net core, encrypted cookies cannot be directly shared between the two. Instead we need to create a compatible data protector as explained at 
c# - share authentication cookie between .NET Framework and .Net Core - Stack Overflow

Visual Studio ( or VS Code) strip all attributes from html tags

 This is a very simple shortcut, find and replace using following regex

Find - <(table|tr|td|p|div|span)[\S\s]*?\n?>

Replace - <$1>

Winforms database first application

 This guide explains the steps to create a winforms database first application

http://codehelper.net/entity-framework/winforms-net-core-tips/

SharePoint provider hosted app certificate trust issues

 It is important to configure certificates correctly for a provider hosted app in SharePoint website since the authentication requires communication between Azure AD, SharePoint, and our app, which is hosted on a different IIS server.

I have added this method to TokenHelper class and call it in CSOM webpart methods to trust certificates

public class TokenHelper

    {

            #region public methods

 

            /// <summary>

            /// Configures .Net to trust all certificates when making network calls.  This is used so that calls

            /// to an https SharePoint server without a valid certificate are not rejected.  This should only be used during

            /// testing, and should never be used in a production app.

            /// </summary>

            public static void TrustAllCertificates()

            {

                //Trust all certificates

                System.Net.ServicePointManager.ServerCertificateValidationCallback =

                    ((sender, certificate, chain, sslPolicyErrors) => true);

            }

}

Also there are some articles which describe certificates trust configuration on a sharepoint farm

https://docs.microsoft.com/en-us/sharepoint/troubleshoot/sharing-and-permissions/ssl-certificate-authentication

https://docs.microsoft.com/en-us/sharepoint/administration/exchange-trust-certificates-between-farms

https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/create-high-trust-sharepoint-add-ins

SharePoint CSOM get absolute url from FileRef

 This one liner can return absolute url of an item using its FileRef property

var absoluteUrl = new Uri(context.Url).GetLeftPart(UriPartial.Authority) + serverRelativeUrl;

 Copied from https://www.red-gate.com/simple-talk/blogs/getting-the-absolute-url-of-a-file-in-csom/

SharePoint add in part - postback error localhost refused to connect

 While developing an addin part using CSOM I was able to use a button to postback the data, but the addin part would show the error 'Localhost refused to connect'. So I was trying to find out why the addin part work on initial load but fails to load when postback method return the view.

After investingating the forms collection I noticed that there are some tokens added to the forms collection by sharepoint in the inital part load request. These tokens are used by IIS to validate the user request, thus they need to be sent with every request. The code below solved this issue:

In the controller I added the method CopyTokens

    private void CopyTokens(AddInViewmodel viewModel)

        {

            if (Request.Form["SPAppToken"] != null)

            {

                viewModel.SPAppToken = Request.Form["SPAppToken"];

            }

            if (Request.Form["SPSiteUrl"] != null)

            {

                viewModel.SPSiteUrl = Request.Form["SPSiteUrl"];

            }

            if (Request.Form["SPSiteTitle"] != null)

            {

                viewModel.SPSiteTitle = Request.Form["SPSiteTitle"];

            }

            if (Request.Form["SPSiteLogoUrl"] != null)

            {

                viewModel.SPSiteLogoUrl = Request.Form["SPSiteLogoUrl"];

            }

            if (Request.Form["SPSiteLanguage"] != null)

            {

                viewModel.SPSiteLanguage = Request.Form["SPSiteLanguage"];

            }

            if (Request.Form["SPSiteCulture"] != null)

            {

                viewModel.SPSiteCulture = Request.Form["SPSiteCulture"];

            }

            if (Request.Form["SPRedirectMessage"] != null)

            {

                viewModel.SPRedirectMessage = Request.Form["SPRedirectMessage"];

            }

            if (Request.Form["SPCorrelationId"] != null)

            {

                viewModel.SPCorrelationId = Request.Form["SPCorrelationId"];

            }

            if (Request.Form["SPErrorCorrelationId"] != null)

            {

                viewModel.SPErrorCorrelationId = Request.Form["SPErrorCorrelationId"];

            }

            if (Request.Form["SPErrorInfo"] != null)

            {

                viewModel.SPErrorInfo = Request.Form["SPErrorInfo"];

            }

        }

I called this method just before completing the postback handler

            public ActionResult Index()

        {

            var viewModel = new AddInViewmodel();

           

            TokenHelper.TrustAllCertificates();

            string contextTokenString = TokenHelper.GetContextTokenFromRequest(Request);

 

            if (contextTokenString != null)

            {

                // Get context token

                var contextToken = TokenHelper.ReadAndValidateContextToken(contextTokenString, Request.Url.Authority);

 

                // Get access token

                Uri sharepointUrl = null;

                if (Request.QueryString["SPAppWebUrl"] != null)

                {

                    sharepointUrl = new Uri(Request.QueryString["SPAppWebUrl"]);

                    var accessToken = TokenHelper.GetAccessToken(contextToken, sharepointUrl.Authority).AccessToken;

                }

               

                var spContext = SharePointContextProvider.Current.GetSharePointContext(HttpContext);

                if (spContext != null)

                {

                    using (var clientContext = spContext.CreateUserClientContextForSPHost())

                    {

                        if (clientContext != null)

                        {

                            // Code to fetch data from SharePoint site into view model

 

                        }

                    }

                }

            }

            CopyTokens(viewModel);

 

            return View(viewModel);

        }

Lastly, I have added some hidden controls in the view to persist and send these tokens in each new postback request, also note the querystring parameters added to reqeust.

@using (Html.BeginForm(actionName: "Index", controllerName: "MyAddInWebpart",

    routeValues: new

    {

        SPHostUrl = Request.QueryString["SPHostUrl"],

        SPHostTitle = Request.QueryString["SPHostTitle"],

        SPAppWebUrl = Request.QueryString["SPAppWebUrl"],

        SPLanguage = Request.QueryString["SPLanguage"],

        SPClientTag = Request.QueryString["SPClientTag"],

        SPProductNumber = Request.QueryString["SPProductNumber"],

        SenderId = Request.QueryString["SenderId"]

    }, method: FormMethod.Post, htmlAttributes: new { }))

    {

        @*@Html.AntiForgeryToken()*@

        @Html.HiddenFor(model => model.SPAppToken)

        @Html.HiddenFor(model => model.SPSiteUrl)

        @Html.HiddenFor(model => model.SPSiteTitle)

        @Html.HiddenFor(model => model.SPSiteLogoUrl)

        @Html.HiddenFor(model => model.SPSiteLanguage)

        @Html.HiddenFor(model => model.SPSiteCulture)

        @Html.HiddenFor(model => model.SPRedirectMessage)

        @Html.HiddenFor(model => model.SPCorrelationId)

        @Html.HiddenFor(model => model.SPErrorCorrelationId)

        @Html.HiddenFor(model => model.SPErrorInfo)

<div class="form"><div class="form-group"><div class="form-row">

       <input type="submit" class="btn btn-default" value="Save" />

</div></div></div>

}

c# mvc extended select List

 The last solution in this post explains how extended select list can be implemented in MVC

https://stackoverflow.com/questions/7536631/adding-html-class-tag-under-option-in-html-dropdownlist/

MVC Error Handling

 A good approach to error handling in MVC sites can be found at https://tech.trailmax.info/2013/08/error-handling-in-mvc-and-nice-error-pages/

SQL Snippet for transaction query

SQL snippets in SSMS is a very handy (thouth probably underused) feature to automate some repetative tasks.  A collection of some useful snippets can be found at https://github.com/asathkumara/SSMS17-Code-Snippets

I decided to add a snippet to SSMS for frequently used query template like this

<?xml version="1.0" encoding="utf-8" ?>

<CodeSnippets  xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">

<_locDefinition xmlns="urn:locstudio">

    <_locDefault _loc="locNone" />

    <_locTag _loc="locData">Title</_locTag>

    <_locTag _loc="locData">Description</_locTag>

    <_locTag _loc="locData">Author</_locTag>

    <_locTag _loc="locData">ToolTip</_locTag>

   <_locTag _loc="locData">Default</_locTag>

</_locDefinition>

       <CodeSnippet Format="1.0.0">

              <Header>

                     <Title>Transaction Query Snippet</Title>

                        <Shortcut></Shortcut>

                     <Description>Code Snippet for Transaction Query</Description>

                     <Author>Pranav Kulkarni</Author>

                     <SnippetTypes>

                                <SnippetType>Expansion</SnippetType>

                     </SnippetTypes>

              </Header>

              <Snippet>

                     <Declarations>

                                                       <Literal>

                                  <ID>query_statement</ID>

                                  <ToolTip>Enter your Query statement(s) here.</ToolTip>

                                  <Default>[...]</Default>

                                </Literal>

                                                       <Literal>

                                  <ID>verify_statement</ID>

                                  <ToolTip>Enter your verify statement(s) here.</ToolTip>

                                  <Default>[...]</Default>

                                </Literal>

                                                      

 

                     </Declarations>

                     <Code Language="SQL"><![CDATA[

DECLARE @exec int = 1

DECLARE @commit int = 0

DECLARE @verify int = 0

 

BEGIN TRAN

IF @exec = 1 BEGIN

       -- Query Statements --

       $query_statement$

END

if @verify = 1 begin

       -- Verify Statements --

       $verify_statement$

END

IF @commit = 1 BEGIN

       COMMIT TRAN

END

ELSE BEGIN

       ROLLBACK TRAN

END

 

                     ]]>

                     </Code>

              </Snippet>

       </CodeSnippet>

</CodeSnippets>