Xamarin.Forms and EntityFrameworkCore 3.x how to properly create a database and apply migrations? - sqlite

Question

what is the proper way to create an EF Core database on an Android/iOS device with Xamarin.Forms and EntityFrameworkCore?
I've come across the EnsureCreated vs Migrate thing and since I'm planning on changing the database structure in the future, I'd like to be able to apply those migrations to an existing database, thus I've chosen the Migrate approach.
However, when I call the Migrate method, it doesn't seem to create a database. I've managed to make it work in case I copy the pre-generated database file on the devices beforehand, but that's not what I want. Is there a way to tell EF Core to check if there's an existing database, create a new database if not, and then apply pending migrations to it?
Here's what I've done so far:
I've created a .net standard class library "Data" that will hold all my database classes (context, models, and migrations).
I've changed the TargetFramework of the "Data" project from <TargetFramework>netstandard2.0</TargetFramework> to <TargetFrameworks>netcoreapp2.0;netstandard2.0</TargetFrameworks> so I could run PMC commands on it.
I've installed these nuget packages to the "Data" project:
EntityFrameworkCore
EntityFrameworkCore.Sqlite
EntityFrameworkCore.Tools
EntityFrameworkCore.Design
I've created a database context class. I've made two constructors for it. The default one will only be used by the PMC commands for generating migrations. The other one will be used in production.
public class MyTestContext : DbContext
{
private string _databasePath;
public DbSet<Issue> Issues { get; set; }
[Obsolete("Don't use this for production. This is only for creating migrations.")]
public MyTestContext() : this("nothing.db")
{
}
public MyTestContext(string databasePath)
{
_databasePath = databasePath;
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
//I've also tried Filename={_databasePath} here, didn't work either
optionsBuilder.UseSqlite($"Data Source={_databasePath}");
}
}
I've created a test model class, just to have something to play with
public class Issue
{
public string Id { get; set; }
}
I created an inital migration using this command, which completed successfully:
Add-Migration Migration001 -Context MyTestContext -Output Migrations
I added a call to the Migrate method in the App.xaml.cs of my Xamarin.Forms project to test if it works.
public partial class App : Application{
//... other code
protected override async void OnStart()
{
base.OnStart();
using (var db = new MyTestContext(_dbPath))
{
try
{
db.Database.Migrate();
db.Issues.Add(new Issue
{
Id = "TestIssueId"
});
db.SaveChanges();
}
catch (Exception ex)
{
Debug.WriteLine(ex);
}
}
}
//... other code
}
The _dbPath variable contains this (on Android where I'm testing it):
Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "test.db");
After all this, I'm getting this exception:
Microsoft.Data.Sqlite.SqliteException: SQLite Error 1: 'no such table: Issues'.