# Connect to MySql in .NET and Entity Framework

'define expected-reading 3 min
'define created 21 May 2020
'define edited 19 June 2021
[$pagenav]

:contents
.numbered
1. [url #nuget-packages NuGet packages]
2. [url #connection-string Connection string]
3. [url #connecting Connecting]
   .numbered
   1. [url #asp.net-startup ASP.NET Startup]
   2. [url #dbcontext-child-class DBContext child class]


I have found that connecting a [`.NET`] application to a [`MySql`] database (with Entity Framework) can be tricky. Here is what works for me.

Also, [url https://www.nuget.org/packages/MySql.Data.EntityFrameworkCore/ MySql.Data.EntityFrameworkCore] has been [=depricated=] since [*October 2020*]. If you need setup instructions with it, read [url https://gitlab.com/Syndamia/syndamiadotcom/-/blob/0510e29526c6d7681587fff4c98a339e8c69e9b5/src/blog/connect-to-mysql-in-csharp-ef/article.md this].

## NuGet packages

You'll need to install [url https://www.nuget.org/packages/Pomelo.EntityFrameworkCore.MySql/ Pomelo.EntityFrameworkCore.MySql]. It provides the stuff necessary for connecting and using a [`MySql`] database.

## Connection string

There are [url https://www.connectionstrings.com/mysql/ a lot] of ways to setup the connection string but I've found that this one works the best:

```
"server=localhost; port=YOUR-PORT; user id=YOUR-USER-ID; password=YOUR-PASSWORD; database=NAME-OF-DATABASE; SslMode=none"

If you are using [`MySQL Workbench`] and you don't know your port and id, you can look at the server information from the [`MySQL Connections`] page.

[image ./img/connections.png MyServer root 127.0.0.1:3306] In this example, the user id is _root_ and the port is _3306_.

## Connecting

To connect, you'll need to call the [`UseMySql`] method, either in [url #asp.net-startup ASP.NET Startup] or in a [url #dbcontext-child-class DBContext child class].

The method requires at least two arguments: connection string and [`MySql`] server version. The latter you can find, by going to the [`Help/About Workbench`] window inside [`MySQL Workbench`].

[image ./img/about-workbench.png]
[image ./img/workbench-version.png]

For the server version argument, create a new object of type [`MySqlServerVersion`] and give it's constructor a new object of type [`Version`], to which you give the version numbers. The result should look something like this:

```c#
.UseMySql(CONNECTION_STRING, new MySqlServerVersion(new System.Version(8, 0, 21)))

Where [`CONNECTION_STRING`] is a (constant) variable that contains your connection string, and 8, 0, 21 are the version numbers.

### ASP.NET Startup

For [`ASP.NET`] applications, the connection must be put inside the [`ConfigureServices`] method of the [`Startup.cs`] file. If you already have a [`.UseSQL`] method call in there, just replace it with your [`.UseMySql`] method and arguments.

The result should look something along the lines of:

```c#
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddDbContext<AppDbContext>(opt =>
    {
        opt.UseMySql(...);
    });
}

### DBContext child class

Another way to connect is via a [`DBContext`] child class (so, inside your own DB context). Just, override the [`OnConfiguring`] method and call the [`.UseMySql`] method from the [`optionsBuilder`] parameter.

```c#
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder.UseMySql(...);
}