We Keep Coding

How can I add PostgreSQL to an existing Entity Framework 6 project while keeping the existing SQL Server provider intact?

Disclaimer: I'm a junior dev and still trying to wrap my head around EF6.
Our team has a .NET Framework 4.7 / Entity Framework 6 project which relies on MS SQL Server for its data. We just upgraded to Visual Studio 2022 but it seems like some of the recommended tools don't work on VS2022. We use database first for EF.
Recently, our team decided to add a create a new PostgreSQL database and we need to add support for it in our existing project.
I've installed the following packages:
Npgsql
EntityFramework6.Npgsql
I was advised to also install the following VS extension:
Npgsql PostgreSQL Integration
But it seems like it is only compatible up to VS2019 and has been abandoned.
In order to test if I could even set this up at all with the recommended VS extension, I used Visual Studio 2019 instead of 2022.
After installing the items listed above, my web.config file now has this entityFramework config:
<entityFramework>
<defaultConnectionFactory type="Npgsql.NpgsqlConnectionFactory, EntityFramework6.Npgsql" />
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
<provider invariantName="Npgsql" type="Npgsql.NpgsqlServices, EntityFramework6.Npgsql" />
</providers>
</entityFramework>
and this system.data config:
<system.data>
<DbProviderFactories>
<remove invariant="Npgsql" />
<add name="Npgsql Provider" invariant="Npgsql" description=".NET Framework Data Provider for PostgreSQL" type="Npgsql.NpgsqlFactory, Npgsql, Version=4.1.3.0, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7" />
</DbProviderFactories>
</system.data>
At this point, I attempted creating a new ADO.NET Entity Data Model, I was able to choose the table and procedure I wanted.
This is where I got stuck.
A new connectionString was added to my web.config, alongside the encrypted connectionString we were already using for SQL Server. When testing, it throws an exception saying that I cannot have an unencrypted connectionString next to an encrypted connectionString.
I tried placing the connectionString within the code but then it throws errors when parsing the connectionString, saying that it does not recognize the parameters. I used the same parameters from the connectionString that was automatically generated.
So, it seems like it's reading the Postgres connectionString with the SQL Server provider instead of the PostgreSQL provider.
Any suggestions? Or resources I can use to help me along the way? Thanks in advance.

Visual Studio 2017 not showing MySQL in connection list

I am using "Visual Studio 2017 Professional". I can not get a project to recognize that MySQL is an available DB option. MySQL does not show up in the list of possible connections when I create a new model. I know that there are tons of SO questions and other web pages on this topic because I have tried a lot of the suggestions. Each is subtlety different in cause and solution. None of the solutions seem to work for me.
I have tried the following with VS 2017 and 2015 with the same results. I have older versions of VS available but it didn't seem worthwhile to march that far back. I have also tried installing the latest and older versions of MySQL both with the "Community Installer" and the standalone msi's when necessary. I went back to the "latest" pre-6.10 version of MySQL.
To begin, this saga started last week when I noticed that nuget had MySQL package updates available. I applied them and then went to upgrade the installed MySQL componants with the Community Installer. The nuget changes did apply. The Community Installer could not uninstall MySQL for VS though. The system installer could not uninstall it. Rebooting and power-cycling did nothing.
On the advice of our local tech support folks I used a third party uninstaller that turned out to be more aggressive than we imagined. It seems to have randomly stommped across the registry erasing whatever it found. Long story short(er), I ended up having my machine reimaged. So, I have a fresh windows install.
Given the fresh Win10 platform, I installed the various things I normally use including the VS versions I typically use. I installed the latest Community MySQL installer. I did a "custom" MySQL install because I don't need a server on this device or fabric or many other things.
I finished the basic reinstall of everything then rebooted just to be sure. I started VS 2017 and created a new web app with the latest available version of .Net (4.6.1). I applied nuget updates and added EntityFramework and MySQL.Data. I then tried to create a new "code first" model.
I can get to the point where I am asked to create a connection. When I click the button the list of available DB providers only shows MS SQL.
I have seen the articles that say to add lines to Web.config and I have seen the MySQL .Net Connector docs that say the same things. I can see the MySQL entries in Web.config but they do not show up when creating a connection.
An oddity is that I can go to Tools -> Connect to Database and see EVERY DB type my machine knows about including MySQL. I can create the connection string and it works. I can see the DB in "Server Explorer` but that doesn't make it available to code.
Ok, I have followed the above steps over and over including downgrading the version of EntityFramework as well as the MySQL version.
My most recent attempt has me back to the latest version of VS and MySQL. The relevant (I think) section of the Web.config file follow. Note the defaultConnectionFactory entry is LocalDbConnectionFactory. I have changed that to SqlConnectionFactory but it has not made a difference. I have also changed the order of the providers and the order of the major blocks.
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="mssqllocaldb" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient"
type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
<provider invariantName="MySql.Data.MySqlClient"
type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.10.6.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d">
</provider>
</providers>
</entityFramework>
<system.data>
<DbProviderFactories>
<remove invariant="MySql.Data.MySqlClient" />
<add description=".Net Framework Data Provider for MySQL" invariant="MySql.Data.MySqlClient"
name="MySQL Data Provider"
type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.10.6.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
</DbProviderFactories>
</system.data>
Edit
My current impression is that VS 2017 is an unusable mess masquerading as a released, salable product. I have returned to 2015.
I have come closer to getting this to work in 2015. I have the latest MySQL items for VS and .Net installed. I have downgraded the nuget EF package to 6.0 and the MySql packages to 6.8.8.
In, what I am now calling, "the good old days" I could add a new model to an MVC project by selecting the Models folder; selecting "Add New Item"; choosing ADO.Net model; select a connection option (MySQL); enter the connection info; choose DB First or Code First and wait for the scaffolding fun to finish.
Now, I have to first go to Tools -> Connect to Database and create a conenction to a MySql DB. If I do not do this I will not see MySQL in the list of possible connections later. I then clean and build the project. Next i try to create the model as above. Noe I can see the MySQL connection option and I can enter the DB creds and test the connection.
The next step is to choose DB First or Code First. In either case, clicking the "next" button flashes a blank pop-up that then vanishes. No errors are shown and no connection is made.
It was never this hard in the past.
I have tried a lot of different MySQL and EF versions on 2015 and 2017 at this point. If there is a magic combo please tell me.

I have been fighting this fight for two weeks. I FINALLY found a combo of versions that works for me. The following was applied to a pristine re-image of my Win10 desktop two weeks ago. All patches were applied to system software before starting to deal with MySql.
Just this morning I re-read the post in this thread (MySql Forums): https://forums.mysql.com/read.php?174,659102,660369#msg-660369
I thought that I had tried those suggestions before but I must have messed up one of the versions. I think that poster's basic strategy is sound. In my case I uninstalled all local MySql parts and the installer.
I downloaded MySQL for Visual Studio - the Latest Development version (2.0.5 msi as of this writing) and installed that.
I found the OLD versions of the .Net Connector and installed 6.9.11
In VS 2017 I created a dummy project using .Net 4.6.1.
I applied pending VS updates.
I built the project.
I went to "Project -> Manage Nuget Packages" and installed / downgraded EntityFramework to 6.0.
I installed MySql.Data, MySql.Data.Entity and MySql.Web all at version 6.9.11
I cleaned and built the project then tried to add a new "Code First" model from a MySql DB... IT WORKED!

Thank you 7 Reeds for coming back with an answer. It led me to get it working, although I did it slightly differently.
In VS 2017 to connect to MySQL 5.6:
Uninstall any MySQL products from the machine
Set Target framework to .NET Framework 4.5.2
Uninstall EntityFramework and any MySQL packages in Nuget
Install MySql.Data.Entity (6.10.7)
It will also install the needed versions of the Nuget packages MySql.Data (6.10.7), EntityFramework (6.1.3), and BouncyCastle (1.8.3.1).
The MySql.Data.Entity package says it depends of Google.Protobuf, but it didn't install it and it works fine for me.
It added References in my project to BouncyCastle.Crypto (1.8.3.0), EntityFramework (6.0.0.0), MySQL.Data (6.10.7.0), and MySql.Data.Entity.EF6 (6.10.7.0).
Close Visual studio
Install 'MySQL for Visual Studio' (1.2.8)
Install 'Connector/NET' (6.10.7)
Delete the bin and obj folders
Open Visual Studio and Rebuild Solution
Add New Item > ADO.NET Entity Data Model > Now you're in the wizard
Select EF Designer from database
On the next screen ('Entity Data Model Wizard'), click New Connection...
On the 'Connection Properties' screen click the Change... button for the 'Data source'
You should be able to select the MySQL Database as the 'Data source'
The 'Data provider' should auto-populate with .NET Framework Data Provider for MySQL
Yay! Continue on like you normally would
For posterity, here's the app.config for my WPF application:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --></configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
</startup>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="v13.0" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
<provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.10.7.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
</providers>
</entityFramework>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="MySql.Data" publicKeyToken="c5687fc88969c44d" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-6.10.7.0" newVersion="6.10.7.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
<connectionStrings>
<add name="MyDB" connectionString="metadata=res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl;provider=MySql.Data.MySqlClient;provider connection string="server=my.example.com;user id=NotMyRealUserID;password=NotMyRealPassword;persistsecurityinfo=True;database=MyDatabase"" providerName="System.Data.EntityClient" />
</connectionStrings>
</configuration>
I'm not sure what created this, but I have a 'User variable' in my 'Environment Variables' named MYSQLCONNECTOR_ASSEMBLIESPATH with value C:\Program Files (x86)\MySQL\MySQL Connector Net 6.10.7\Assemblies\v4.5.2

At appsettings.json:
"ConnectionStrings": { "DefaultConnection": "Server=localhost;database=MusicStoreDB;user id=root;Charset=utf8;" },
At ConfigureServices() in Startup.cs :
using Microsoft.EntityFrameworkCore; using MySql.Data.MySqlClient; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.DependencyInjection;
... services.AddDbContext(options => options.UseMySQL(Configuration.GetConnectionString("DefaultConnection")));
Note: Change to:
UseMysql <-------------- When using Pompelo EntityFrameworkCore

Postgresql with EF6 creation of ddex is failed

I'm trying to to work with Entity Framework 6, and connect it to a Postgresql
database.
I'm using npgsql.Entityframework, but get an error when creating the ddex file.
Can someone knows why?
Thanks.

Install Npgsql, to work between Entity Framework to PostgreSql:
Download and install the Setup_NpgsqlDdexProvider.exe from https://github.com/npgsql/npgsql/releases.
Open Visual-Studio, click on the tab: TOOLS -> Setup Npgsql DbProviderFactories.
A window will open, you need to click OK.
Close Visual-Studio and open as administrator the two machine.config files of .NET with notepad.
There are two file that we need to edit, you can find the file at the paths:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config\machine.config
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\machine.config
Add the flowing element to the files:
<system.data>
<DbProviderFactories>
<remove invariant="Npgsql"/>
<add name="Npgsql Data Provider"
invariant="Npgsql"
description=".Net Data Provider for PostgreSQL"
type="Npgsql.NpgsqlFactory, Npgsql, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7"
support="FF" />
</DbProviderFactories>
</system.data>
Reopen Visual-Studio at the wanted project.
Install Entity Framework through Nuget.
Open the Package Manager Console and insert the commend:
Install-Package EntityFramework6.Npgsql
Check that the wanted DLL are references, like so:
If not add the DLL manually. The sopose to be at the paths:
C:\Users\YOURCOMPUTERNAME\documents\visual studio 2015\Projects\PostgreSqlVsEfwDemo\packages\Npgsql.3.0.5\lib\net45\Npgsql.dll
C:\Users\ YOURCOMPUTERNAME\documents\visual studio 2015\Projects\PostgreSqlVsEfwDemo\packages\EntityFramework6.Npgsql.3.0.5\lib\net45\EntityFramework6.Npgsql.dll
Open the App.config\Web.config and add two elements:
The provider element at entityFramework -> providers. as so:
The provider element at DbProviderFactories. as so:
<system.data>
<DbProviderFactories>
<remove invariant="Npgsql" />
<add name="Npgsql Data Provider" invariant="Npgsql" description=".Net Data Provider for PostgreSQL" type="Npgsql.NpgsqlFactory, Npgsql, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7" support="FF" />
</DbProviderFactories>
If the <system.data> element isn't exist, add it all.
Now lets add Entity Data Model like so:
Select "EF Designer from database"
Click on "New Connection"
Choose the "PostgreSQL Database" as the Data source:
Filled the fields:
HOST
USERNAME
PASSWORD
PORT
DATABASE (fill this field last.)
Click on "Test Connection" to see if it works.
Continue with Entity Framework as regular.
Hope it's help you.
This document of Npgsql Docs really helped me, but still have problems.

C# program is looking for sql server compact 3.5, but I'm using 4.0

Okay, this one is really puzzling me, and I apologize if the title of the question doesn't accurately describe what my problem is.
I have a program made in C#, using Entity Framework and SQL Server CE. I developed it on Windows 7, and it works fine. I also have a Windows 8.1 machine that I've tested it on, and it works fine on that too.
However, on a few Windows 8.1 computers, the program crashes as soon as it tries to access the database. I get the following error:
Unhandled Exception: System.InvalidOperationException: No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlServerCe.3.5'. Make sure the provider is registered in the 'entityFramework' section of the application config file. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information.
Now, this really confuses me, because I have the latest NuGet package for SQL Server CE installed on my project (4.0). I used the SQL Server CE toolbox to explicitly create a SQL Server CE 4.0 database, I distributed the 4.0 dll's with the application, and I explicitly have version 4.0 listed in my app.config file (invariantName="System.Data.SqlServerCe.4.0").
So, why does the error say System.Data.SqlServerCe.3.5? Why does this error only occur on a couple of Windows 8.1 machines?
(I also searched through my entire solution, and the text "3.5" doesn't even appear anywhere.)
I found similar errors, and I tried (from this question) to include this:
private volatile Type _dependency;
public MyClass()
{
_dependency = typeof(System.Data.Entity.SqlServer.SqlProviderServices);
}
Has no effect, I still get the same exact answer.
Anyways, if anybody has any ideas, I would greatly appreciate any kind of input.

I think problem is both SQL Server CE components installed in your system.
My solution :
<DbProviderFactories>
<remove invariant="System.Data.SqlServerCe.3.5" />
<remove invariant="System.Data.SqlServerCe.4.0" />
<add name="Microsoft SQL Server Compact Data Provider 4.0"
invariant="System.Data.SqlServerCe.4.0"
description=".NET Framework Data Provider for Microsoft SQL Server Compact"
type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=4.0.0.1, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
</DbProviderFactories>

I had the same issue and solved it based on this link.
Find this section in your App.config:
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Data.SqlServerCe" publicKeyToken="89845dcd8080cc91" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.1" newVersion="4.0.0.1" />
</dependentAssembly>
</assemblyBinding>
</runtime>
And change oldVersion="0.0.0.0-4.0.0.1" to oldVersion="4.0.0.0-4.0.0.1"

Check your config file and add an Entry for the DbProviderFactories like this:
<system.data>
<DbProviderFactories>
<remove invariant="System.Data.SqlServerCe.4.0" />
<add name="Microsoft SQL Server Compact Data Provider 4.0" invariant="System.Data.SqlServerCe.4.0" description=".NET Framework Data Provider for Microsoft SQL Server Compact" type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=4.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
</DbProviderFactories>
</system.data>

Take a look at your project references, you may be referencing to the wrong dll

mysql and asp.net identity

I am not able to get asp.net mvc5 identity to work with mysql. Here is the web.config part .Could it be beacuse of EF6 not working with mvc5 ?
<system.data>
<DbProviderFactories>
<remove name="MySQL Data Provider"/>
<add name="MySQL Data Provider"
invariant="MySql.Data.MySqlClient"
description=".Net Framework Data Provider for MySQL"
type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
</DbProviderFactories>
</system.data>
entityFramework>
<defaultConnectionFactory type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data" />
<providers>
<provider invariantName="MySql.Data.MySqlClient"
type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity" />
</providers>
</entityFramework>
The error is :
Additional information: The 'Instance' member of the Entity Framework
provider type 'MySql.Data.MySqlClient.MySqlProviderServices,
MySql.Data.Entity, Version=6.7.4.0, Culture=neutral,
PublicKeyToken=c5687fc88969c44d' did not return an object that
inherits from 'System.Data.Entity.Core.Common.DbProviderServices'.
Entity Framework providers must inherit from this class and the
'Instance' member must return the singleton instance of the provider.
This may be because the provider does not support Entity Framework 6
or later

That because you are referencing EF 6, and MySQL Connector still does not support EF6. You can either downgrade to EF 5 or get the MySQL Connector Alpha.
Do this (KEEP A COPY OF WHAT YOU JUST PASTED):
Erase all references to EF6
Get EF 5 from Nuget (open a NuGet console and type Install-Package EntityFramework -Version 5.0.0 )
Regenerate your Entities
Make sure you get the <DbProviderFactories> and <providers> sections just like you have.

After you do what David suggested look in all of the App.config files and make sure that all of the depdentAssembly settings look something like this.
<dependentAssembly>
<assemblyIdentity name="EntityFramework" publicKeyToken="b77a5c561934e089" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-5.0.0.0" newVersion="5.0.0.0" />
</dependentAssembly>
The important part is the bindingRedirect.

I came across the MySql.Data.Entity.EF6 NuGet package which should fix your issue. I found I had to completely remove all references to MySql and EF before I could get this to work properly (including all web.config references). The package has a dependency on EF6, so will install it as part of the package install process.

You can also use finished implementation of MySQL ASP.NET Identity 2.1 provider which uses ADO.NET to communicate with MySQL.
This is available as NuGet package and you can read more on this blog post:
ASP.NET Identity 2.1 implementation for MySQL