Add identity into an ASP.NET Core 2.1 MVC project and maintain full control of the Identity UI

To maintain full control over the Identity UI in an ASP.NET Core 2.1 MVC project, scaffold the identity using the Windows version of Visual Studio 2017.

Scaffold the Identity

  1. Right click the web application project and select Add, New Scaffolded Item
  2. On the left side of the Add Scaffold dialog select Identity, and click the Add button
  3. Select your existing Layout page, so the scaffolding will not overwrite it
  4. Select the Identity functions (files) you want to override, and click the down arrow to select your existing data context class
  5. The MY_SOLUTION\MY_WEBAPP\ScaffoldingReadme.txt file contains tasks to do to set up the Identity UI. Based on that
    1. Add the following lines to the Configure method of the Startup.cs file in this order. If a line is already in the file, make sure the order is correct.
      app.UseStaticFiles()
      app.UseAuthentication()
      app.UseMvc()
    2. Add to the ConfigureServices method of the Startup.cs file, if the line is not there.
      services.AddMvc()
  6. The Aeras, Identity, Pages, Account folder contains the .cshtml files you can modify.
  7. The code is in the .cshtml.cs file

Use your own SMTP server

To configure Identity to use you own SMTP server to send the Forgot my password and email verification emails, register a custom email sender.

  1. Add to the ConfigureServices method of the Startup.cs file
    // using Microsoft.AspNetCore.Identity.UI.Services;
    services.AddSingleton<IEmailSender, EmailSender>();
  2. Create the EmailSender class in the web application project
    // using Microsoft.AspNetCore.Identity.UI.Services;
    // using System.Threading.Tasks;
    public class EmailSender : IEmailSender
    {
        public Task SendEmailAsync(string sTo, string sSubject, string sMessage)
        {
            MyMessagingClass messaging = new MyMessagingClass();
    
            // Send an email message with SMTP
            messaging.MySendEmailMethod(sTo, sSubject, sMessage);
            
            return Task.CompletedTask;
        }
    }

For more information see https://docs.microsoft.com/en-us/aspnet/core/security/authentication/scaffold-identity?view=aspnetcore-2.1&tabs=visual-studio#scaffold-identity-into-a-razor-project-with-authorization

 

 

Add jQuery DataTables grid to an ASP.NET Core MVC web application

ASP.NET does not provide sortable, searchable tables. jQuery DataTables is a popular way to display user-friendly data in an ASP.NET Core MVC web application.

Set up the environment

  1. Add the System.Linq.Dynamic.Core NuGet package to the web application
  2. Add the JsonOptions to the Startup.cs file
     using Newtonsoft.Json.Serialization;
  3. Add the AddJsonOptions to the services.AddMvc() section in the ConfigureServices() method of the Startup.cs file
     .AddJsonOptions(options => options.SerializerSettings.ContractResolver = new DefaultContractResolver());

Add the jQuery DataTables grid to the view

  1. Add the script and css references to the bottom of the view
    @section Scripts {
    	<!-- For the DataTables grid -->
    	<link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.19/css/jquery.dataTables.css">
    	<script type="text/javascript" src="https://cdn.datatables.net/1.10.16/js/jquery.dataTables.min.js"></script>
    
    	<!-- Page-specific script -->
    	<script src="~/js/MY-CONTROLLER_MY-PAGE.js" asp-append-version="true"></script>
    }
  2. Add to the page-specific MY-CONTROLLER_MY-PAGE.js file to the wwwroot\js directory
    $(document).ready(function () {
    
      // Set up the DataTable grid
      $('#serverTable').DataTable();
    
    });
  3. Create a table with the same id referenced in the script
    @if (null != Model.ServerList) {
      <table id="serverTable" class="table table-striped table-bordered dt-responsive nowrap" width="100%">
        <thead>
          <tr>
            <th></th>
            <th>Name</th>
            ...
          </tr>
        </thead>
        <tbody>
          @foreach (ServerInstance instance in Model.ServerList) {
            <tr>
              <td><input type="checkbox" asp-for="@instance.Selected" /></td>
              <td>@instance.NameTag</td>
              ...
            </tr>
          }
        </tbody>
      </table>
    }

 

Error unprotecting the session cookie in an ASP.NET Core MVC application.

The new ASP.NET Core MVC framework automatically displays a message for the user to accept the application’s privacy policy. The default message is “Use this space to summarize your privacy and cookie use policy.” No cookies are saved in the user’s browser until they click the Accept button.

Even after accepting the terms, if the browser contains old, stale cookies the application may not be able to save cookies. The log contains

warn: Microsoft.AspNetCore.Session.SessionMiddleware[7]
Error unprotecting the session cookie.
System.Security.Cryptography.CryptographicException: The key … was not found in the key ring.

If the web application works in a new incognito window, clear the old cookies in your browser.

In Google Chrome

  1. In the Chrome menu select Clear Browsing Data
  2. On the Clear browsing data page select All time, and Cookies and other site data

 

 

Set the environment for an ASP.NET Core MVC web application

When the ASP.NET Core MVC web application starts, reads the name of the environment for an environment variable of the host computer. The compiled application contains the configuration for all supported environments, making possible to build and deploy the same artifact in every environment.

If the ASPNETCORE_ENVIRONMENT environment variable is not defined, the Production environment settings are loaded.

In Visual Studio the web application project sets the value on the Debug tab.

To set the environment on the server

Windows

To set the value globally that is preserved after restart

Command prompt

  1. Open the command prompt window and execute
    setx ASPNETCORE_ENVIRONMENT Development /M

PowerShell

  1. Open a PowerShell window and execute
    [Environment]::SetEnvironmentVariable("ASPNETCORE_ENVIRONMENT", "Development", "Machine")

macOS

  1. Add to the .bashrc or .bash_profile file
    export ASPNETCORE_ENVIRONMENT=Development

 

Configure the ASP.NET Core MVC web application

Create the environment-specific appsettings.json files

  1. In the web application project click the arrow next to the appsettings.json file to reveal the Development configuration file
  2. Right-click the appsettings.Development.json file and select Copy

  3. Right click the web application project and select Paste

  4. Rename the appsettings – Copy.Development.json file to appsettings.Production.json

  5. The file will automatically move under the appsettings.json file

Edit the configuration files

  1. Open the appsettings.Production.json file and add the connection string
    {
        "ConnectionStrings": {
            "DefaultConnection": "Server=MY_DATABASE_URL;Database=MY_DATABASE_NAME;Username=MY_USERNAME;Password=MY_PASSWORD"
        }
    }
    
    

 

Return values to the controller in the model from the ASP.NET MVC view

When we create an ASP.NET MVC web application, the model (an object) is the easiest way to return values from the view to the controller.

For the view to be able to return the values in the model, make sure the model contains properties, not fields, for every value with { get; set; }

public class MyViewModel
{
    public string ID { get; set; }
}

Add the model to the view at the top of the .cshtml file

IMPORTANT!!! To return values for properties that do not have controls on the page, like IDs that are not displayed, add a hidden field to the view.

@model MyViewModel
<form  asp-action="Index" asp-controller="My">
    <input asp-for=@Model.ID type="hidden" >
</form>

Send the data in the model to the view from the get method in the controller

public class MyController : Controller
{
    public IActionResult Index()
    {
         MyViewModel model = new MyViewModel();
         model.ID = "MY_ID";
         return View(model);
    }
}

Read the value from the model in the post method of the controller and send the model back

public class MyController : Controller
{
    [HttpPost, ValidateAntiForgeryToken]
    public IActionResult Index(MyViewModel model)
    {
        string ID = model.ID;
...
        return View(model);
    }
}

 

Reverse engineer a database with AspNetCore in Visual Studio

For some reason the .NETCore designers did not think, that developers want to follow best practices by separating the data layer from the presentation layer.

The Entity framework out of the box only works if the database is accessed from the main application project.

When we try to reverse engineer a PostgreSQL database from a class library with the command:

cd MY_CLASS_LIBRARY_DIRECTORY
dotnet ef dbcontext scaffold "Host=localhost;Database=MY_DATABASE_NAME;Username=MY_USERNAME;Password=MY_PASSWORD" Npgsql.EntityFrameworkCore.PostgreSQL

we get the error message:

The specified framework version ‘2.1’ could not be parsed
The specified framework ‘Microsoft.NETCore.App’, version ‘2.1’ was not found.
– Check application dependencies and target a framework version installed at:
/usr/local/share/dotnet/
– Installing .NET Core prerequisites might help resolve this problem:
http://go.microsoft.com/fwlink/?LinkID=798306&clcid=0x409
– The .NET Core framework and SDK can be installed from:
https://aka.ms/dotnet-download
– The following versions are installed:
2.0.0 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
2.1.2 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
2.1.3 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

The problem is, that the …runtimeconfig.json files are only automatically generated in the bin/netcoreapp2.1 directory of the main application project, those are missing from all class libraries.

To enable the automatic generation of the …runtimeconfig.json files, add a line to the <PropertyGroup> section of the data layer class library project (.csproj) file.

<PropertyGroup>
...
<GenerateRuntimeConfigurationFiles>True</GenerateRuntimeConfigurationFiles>
...
</PropertyGroup>

 

Use two GitHub accounts on the same computer

Many developers have multiple GitHub accounts. One for personal projects, and another one for their work or business. There is a way to access multiple accounts simultaneously from the same computer. Only one account at a time can be configured using the HTTP connection, but we can configure the rest of the accounts using SSH.

There are many great articles on this topic, but most of them only provide partial instructions on how to set up multiple GitHub accounts on the same computer. In this post, I will document all the necessary steps to set up two accounts.

Usually, you don’t have much control over what GitHub connectivity is used for the company account, it can be dictated by the customer or your workplace, but you can always control what to use for your personal account. With SSH you can specify all aspects of your personal account, so you can leave the default SSH or HTTP connection for the business or company account.

In this post, we will set up two accounts with SSH connection. Even if the business account currently uses HTTP, it makes sense to set up SSH for that account too, in case they will switch to SSH at a later time.

Create two keys

    1. Open a terminal window and start the authentication agent to avoid the “Could not open a connection to your authentication agent” error later
       eval `ssh-agent -s`
    2. Create the personal SSH key
      ssh-keygen -t rsa -C "MY_PERSONAL_EMAIL@ADDRESS"

      when asked for the file name by the “Enter file in which to save the key“prompt, save the key as id_rsa_pers

    3. Add the personal key to the authentication agent
      ssh-add id_rsa_pers
    4. Create the business SSH key
      ssh-keygen -t rsa -C "MY_COMPANY_EMAIL@ADDRESS"

      when asked for the file name by the “Enter file in which to save the key“prompt, save the key as id_rsa_COMPANY_NAME

    5. Add the business key to the authentication agent
      ssh-add id_rsa_COMPANY_NAME

Configure SSH to use the two new keys

  1. Create the SSH config file
    touch ~/.ssh/config
  2. Open the ~/.ssh/config file with a text editor
  3. Add the following lines
    #Personal GitHub
    Host github-pers
      HostName github.com
      User MY_PERSONAL_GITHUB_USERNAME
      IdentityFile ~/.ssh/id_rsa_pers
    
    #Company GitHub
    Host github.com
      HostName github.com
      User MY_COMPANY_GITHUB_USERNAME
      IdentityFile ~/.ssh/id_rsa_COMPANY_NAME
    

Upload the keys to your GitHub accounts

  1. Log into the GitHub website with your personal credentials
  2. In the upper right corner click the down arrow next to your icon, and select Settings
  3. On the left side select SSH and GPG keys
  4. Click the New SSH key button
  5. Type a name for the key,  paste the contents of the ~/.ssh/id_rsa_pers.pub public key file into the text area, and click the Add SSH key button
  6. Log into Github with your company credentials
  7. Upload the id_rsa_COMPANY_NAME.pub public key file as explained above.

Create a personal repository

  1. Create a new folder, personal-test, and add a file to it on your computer
  2. Initialize the Git repository in the folder
    git init
    git add .
    git commit -m "Initial commit"
  3. Log into your personal GitHub account
  4. Create a new repository, and name it personal-test
  5. On the confirmation page click the SSH button
  6. Copy the …or push an existing… code to a text editor
  7. Edit the origin address to match the “Host” of the personal section in the ~/.ssh/config file, and execute the commands
    git remote add origin git@github-pers:MY_PERSONAL_GITHUB_USERNAME/personal-test.git
    git push -u origin master

Company repositories

For your company account use the default HTTP or SSH GitHub repository address without any modifications.

Add SSH key access to a GitHub repository

Generate an SSH key pair

  1. In a terminal execute
ssh-keygen

Generating public/private rsa key pair.
Enter file in which to save the key : /Users/MY_USERNAME/Git/_Keys/MY_PROJECT/MY_PROJECT_rsa_ci
Enter passphrase (empty for no passphrase):
Enter same passphrase again:

Leave the passphrase empty, many systems cannot work with password protected key pairs.

This process will save the key-pair in two files. The private key with no extension, and the public key with the .pub extension.

Create a new service GitHub user account which will have access to the repository

  1. Create a new email address (GitHub requires unique email addresses for every user)
  2. Register a new user which will have access to the repository

Upload the public key to the service GitHub account

    1. Log into the GitHub account and select Settings in the drop-down in the upper right corner
    2. On the left side select SSH and GPG keys
    3. In the upper right corner select the New SSH key button
    4. Copy the above generated public key to your clipboard.
      On a Mac copy the public key to your clipboard with the command

      pbcopy < /Users/MY_USERNAME/Git/_Keys/MY_PROJECT/MY_PROJECT_rsa_ci.pub
    5. Paste the public key into the textbox

Add the service user as a collaborator to the GitHub repository

  1. Log into the GitHub account that has admin access to the repository
  2. Navigate to the repository and select Settings
  3. Select COllaborators & teams
  4. Enter the username into the search box and click Add collaborator

If you use two-factor authentication in Github

If you use two-factor authentication in your GitHub account, and you need automated access to it, create a Personal Access Token and use it instead of your password. GitHub will not ask you to verify your identity.

Generate a Personal Access Token

    1. Log into your GitHub account
    2. On the left side select Developer settings
    3. Select Personal access tokens
    4. Click the Generate new token button
    5. Select the repo checkbox
    6. Copy the token to your clipboard. This is the last time you are able to see the token.
    7. Save the token at a secure location, and use it instead of your password when you need automated access to your GitHub account.

Ruby tips and tricks

Bang methods

(Exclamation point at the end of the method name)

There are methods that have a permanent or dangerous version. The exclamation point designates to use the dangerous version of the method.

String manipulation

The bang versions of the string manipulation methods (with the exclamation point), modify the string variable in place. Some of these methods are

  • sub
  • gsub
  • reverse
  • sort

The original string ‘gsub’ substitution method:

original = 'My old cat'
new = original.gsub('old', 'new')

results:
original = 'My old cat'
new ='My new cat'

The dangerous (bang) ‘gsub’ method with the exclamation point modifies the original variable:

original = 'My old cat'
original.gsub!('old', 'new')

results:
original = 'My new cat'

Kernel::exit

The script exits with Kernel::exit, but Kernel::exit! causes an immediate exit, bypassing any exit handlers.