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);
    }
}

 

The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)

When I made changes to the web.config file of an ASP.Net C# application, I have accidentally deleted a comma, and I started to get the runtime error message:

The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)

Make sure all necessary commas are there in the config files, Visual Studio does not check the format of those lines. In my case, the error was in

<provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.9.10.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />

Connect to a MySQL database from Visual Studio 2017

As of today weI can connect to a MySQL database, but cannot generate the Entity Data Model from a MySQL database in Visual Studio 2017

To access a MySQL database from Visual Studio 2017

IMPORTANT: First install MySQL for Visual Studio, and after that install MySQL Connector/Net.

If MySQL Connector/Net is already installed on your workstation, uninstall it before installing MySQL for Visual Studio and reinstall MySQL Connector/Net.

Install MySQL for Visual Studio

Available version information is at https://dev.mysql.com/doc/visual-studio/en/visual-studio-intro.html

  1. Close all instances of Visual Studio,
  2. Download the installer from https://dev.mysql.com/downloads/windows/visualstudio/
  3. Start the installer
  4. Click the Complete button,
  5. If you select Typical, make sure the Visual Studio 2017 components are selected

 

Install the MySql Connector/Net the fully-managed ADO.NET driver for MySQL

  1. Download the installer from https://dev.mysql.com/downloads/connector/net/
  2. Download version 6.9.10, because version 6.10.5 throws the

    Inheritance security rules violated by type: ‘MySql.Data.Entity.MySqlEFConfiguration’. Derived types must either match the security accessibility of the base type or be less accessible

    error. More info at https://stackoverflow.com/questions/47227495/inheritance-security-rules-violated-by-type-mysql-data-entity-mysqlefconfigura

  3. Select version 6.9.10, your operating system and click the Download button
  4. If you don’t want to create an Oracle account, click the No thanks… link
  5. Start the downloaded installer
  6. Click the Complete button

Install the NuGet packages

Make sure to install the same version of the NuGet packages as the MySql Connector/Net

Generate Entity Framework Entity Data Model in Visual Studio 2017

Visual Studio 2017 has many project type options, and not all of them support the Entity Framework user interface to generate the Entity Framework Data Model (EDMX) file. If you create an ASP.NET Web Application(.NET Framework) you can add the EDMX file to it. The .NET Core projects do not support the Entity Framework Data Model creation.

For more complex web applications it is good practice to separate the data access layer from the presentation layer. You can even reference the data access project from another solution if that also needs access to the same data.

To be able to use the graphical user interface to generate the Entity Framework Entity Data Model

  1. Add a new Class Library (.NET Framework) type project to the solution,
  2. Right-click the new project and select Add -> New Item
  3. In the Data section select the ADO.NET Entity Data Model
  4. Select EF Designer from database
  5. Continue the process to create the database connection and generate the data model.

Generate the Entity Classes

  1. Open the EDMX file
  2. Right-click the background and select Add Code Generation Item
  3. Select the latest EF DbContext Generator
  4. When the classes have been generated, close the solution and open it again, otherwise, the newly created classes cannot be referenced.

The .NET MVC model has to have a parameterless constructor

When you create a class to be used as the model in a .NET MVC application, the class has to have a parameterless constructor. It is called during the POST when the user clicks the submit button of the form. If the class does not have a parameterless constructor, we will get the following generic error message. None of the breakpoints can help you to find the cause, and there is no entry in the event log.

The website cannot display the page
HTTP 500

Most likely causes:
•The website is under maintenance.
•The website has a programming error.

What you can try:
Refresh the page.
Go back to the previous page.
More information

An error occurred while signing

When you deploy and application in Microsoft Visual Studio with ClickOnce, you need to sign the installer with a key.

To sign the project Visual Studio needs to use the signtool. If the ClickOnce feature is not enabled in Visual studio, it displays the following error message:

An error occurred while signing: SignTool.exe was not found at path C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\bin\signtool.exe

To install the ClickOnce feature and the signtool

On Windows 7

  • In Windows Control panel select Programs and Features,
  • Right click Visual Studio 2015 and select Modify,
  • In the feature list select ClickOnce tools.

On Windows 10

  • In Windows Control Panel select System,
  • On the left side select Apps & features,
  • In the app list click Microsoft Visual Studio 2015,
  • Click the Modify button,
  • In the Visual Studio setup click the Modify button again,
  • In the feature list select ClickOnce Publishing Tools.

 

Troubleshooting

When you have been able to successfully sign your Click Once applications in the past and suddenly you get the error message

An error occurred while signing: Failed to sign bin\Debug\app.publish\….exe. SignTool Error: No certificates were found that met all the given criteria.

it is possible that the certificate you used to sign your app has expired. To check the validity of the certificate

  1. In Visual Studio open the project’s properties page,
  2. On the Signing tab check the expiration date of the certificate.

Create a new certificate

To create a new certificate

  1. On the Signing tab of the project properties page click the Create Test Certificate button,
  2. Enter a password for the new certificate.
  3. Click the down arrow next to the key file name and select the new key file in the dropdown list.
  4. Save the project file and build your application.

 

 

 

No mapping specified for instances of the EntitySet and AssociationSet in the EntityContainer

When you move your Visual Studio solution to another workstation you may encounter the following error message:

System.Data.Entity.Core.MappingException was unhandled by user code
HResult=-2146232032
Message=Schema specified is not valid. Errors:
: error 2062: No mapping specified for instances of the EntitySet and AssociationSet in the EntityContainer …
Source=EntityFramework

 

In this case it may help if you re-import the database objects into the .edmx file.

To import all objects again:

  • Open the .edmx file,
  • Press the Ctrl-A keys to select all tables in the diagram,
  • Press the delete key on the keyboard to delete all tables,
  • Right click the white area and select Model Browser,
  • In the Model Browser expand the {model name}.Store, and the Stored Procedures / Functions element
  • Delete all functions and stored procedures
  • In the {model name} element (the element above the {model name}.Store) expand the Function Imports element
  • Delete all function imports
  • Save the .edmx file
  • Right click the white area of the .edmx file and select Update Model from Database
  • Select all necessary tables, stored procedures, and functions and import them.

If you re-import the tables, but do not delete the stored procedures, functions, and function imports you may get the following error message:

HResult=-2146233079
Message=The function import ‘Tobacco_WebEntities.spGetAgeGroupId’ cannot be executed because it is not mapped to a store function.
Source=EntityFramework

 

Save the key file password in Visual Studio

When you have already set up the project signing of the C# application for ClickOnce deployment, and move the solution to another workstation you may get the following error message when you build the solution:

Severity Code Description Project File Line Suppression State
Error Cannot import the following key file: .....pfx. The key file may be password protected. To correct this, try to import the certificate again or manually install the certificate to the Strong Name CSP with the following key container name: VS_KEY_....

We get this message, because the new workstation does not know the key file password. To solve this problem, we have to save the key file password on the new workstation.

To make your solution work again

  • Open the Visual Studio project properties window,
  • On the Signing tab click the pull down that shows the name of the key file.
  • Select Browse,
  • Select the key file,
  • Enter the password in the Password text box.

Visual Studio 2015 is very slow on Windows 10

When I have upgraded Windows 7 my computer to Windows 10 I have also installed Visual Studio 2015 professional. From the first moment Visual Studio 2015 was very slow. My computer was freezing all the time.

I have read many articles about the slowness of Visual Studio 2015, but I cold not find anything that helped, so I have decided to switch back to Windows 7. Unfortunately after the downgrade process my computer did not boot anymore. Finally I had to reinstall Windows 7 and all my applications. Luckily all my files were on the hard drive, so I did not lose anything.

Since that, I have found the following recommendation at http://stackoverflow.com/questions/31760339/visual-studio-2015-slow

  • Uncheck [Tools->Options->General->Automatically adjust visual experience based on client performance]
  • Uncheck [Use graphics acceleration if available]
  • You can leave [Enable rich client visual experience] checked

Sooner or later I will have to bite the bullet and install Windows 10 again, hopefully by that time Microsoft corrects this very serious problem, or I will try these steps to make it work.

 

NUnit in Visual Studio 2015

To use NUnit in Visual Studio 2015

Create a unit test project and download NUnit from NuGet

  • Start Visual Studio 2015 and open or create a solution
  • In your solution create a new class library for your unit tests
  • Right click the unit test project and select Manage NuGet Packages
  • Type NUnit into the search field
  • Install
    • NUnit
    • NUnit Test Adapter
    • NUnit Runners

Create unit tests

Run the unit tests