尽管拥有正确的NuGet软件包，为什么我仍需要在计算机上安装MySQL连接器？

Question

I've got a C# ASP.NET MVC project using MariaDB with Entity Framework 6.

This project is made in Visual Studio 2017 and it took me some long hours double-checking whether I had the proper MySQL connector's assembly references added as they should, in the form of NuGet packages MySql.Data 8.0.13 and MySql.Data.EntityFramework 8.0.13 (both oficially published by Oracle), because I was getting the following error when browsing Views while debugging:

The ADO.NET provider with invariant name 'MySql.Data.MySqlClient' is either not registered in the machine or application config file.

Until I gave up on it and tried installing the MySQL Connector/NET 8.0 , after which it worked. No changes made to the web.config file other than those performed by NuGet.

I checked the assemblies placed under %ProgramFiles%\\MySql\\Connector by the installer, and they are bit-identical to those pulled by NuGet. Heck, I even deleted the entire folder, and it still worked .

What gives? Are the NuGet packages missing some step they should perform?

Answer 1

I suspect that the Connector/NET 8.0 installer modifies your C:\\Windows\\Microsoft.NET\\Framework64\\v4.0.30319\\config\\machine.config file, which is shared by all .NET applications on the machine. Unfortunately, this is a local change on your machine, which means that your application may not work properly when deployed.

The solution is to add MySql.Data to your app.config (or Web.config ) file. I'm not sure if the NuGet packages are designed to do this automatically or not.

Per the Oracle docs , add this information to app.config :

<system.data>
   <DbProviderFactories>
     <remove invariant="MySql.Data.MySqlClient" />
     <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" 
          type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=8.0.13.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
   </DbProviderFactories>
</system.data>