EF Core migrations

Use EF Core migrations to give a plugin its own database and change its schema. The Schulware and OdaOrg plugins do this.

Each plugin gets its own database

The host passes each plugin a dedicated connection string in PluginServiceContext.ConnectionString. It takes the main connection string and changes the database name to schuly_plugin_<name>, where <name> is ISchulyPlugin.Name in lowercase with spaces replaced by underscores. For example, Schulware Integration becomes schuly_plugin_schulware_integration.

Wire it into your DbContext:

services.AddDbContext<SchulwareDbContext>(options => options.UseNpgsql(context.ConnectionString));

Your migrations never touch the main Schuly database.

Add the packages

A plugin with a database references Microsoft.EntityFrameworkCore, Microsoft.EntityFrameworkCore.Design, and Npgsql.EntityFrameworkCore.PostgreSQL. Copy the references from Schuly.Plugin.OdaOrg.csproj.

Add a migration

You need the dotnet-ef tool. See development setup.

dotnet ef migrations add <Name> --project src/Schuly.Plugin.Schulware

Swap the project path for your plugin. The command writes the migration to the plugin's Data/Migrations/ folder and updates the model snapshot. For a plugin's first migration, add --output-dir Data/Migrations to use the same folder.

Add a design-time factory

dotnet ef builds the DbContext at design time without the runtime DI pipeline. Ship an IDesignTimeDbContextFactory<T> next to your DbContext, such as Data/SchulwareDbContextFactory.cs. Its connection string is a placeholder, because migrations need only the model, not a live database:

internal sealed class SchulwareDbContextFactory : IDesignTimeDbContextFactory<SchulwareDbContext>
{
    public SchulwareDbContext CreateDbContext(string[] args)
    {
        var options = new DbContextOptionsBuilder<SchulwareDbContext>()
            .UseNpgsql("Host=localhost;Database=schulware_design;Username=postgres;Password=postgres")
            .Options;
        return new SchulwareDbContext(options);
    }
}

Apply migrations at runtime

Apply pending migrations from MigrateAsync. The host calls it each time it loads the plugin.

public async Task MigrateAsync(IServiceProvider serviceProvider, CancellationToken cancellationToken = default)
{
    using var scope = serviceProvider.CreateScope();
    var db = scope.ServiceProvider.GetRequiredService<SchulwareDbContext>();
    await db.Database.MigrateAsync(cancellationToken);
}

Use MigrateAsync(), never EnsureCreatedAsync. EnsureCreatedAsync creates the database on the first run but does nothing on later schema changes, so new columns and indexes never reach an existing database. MigrateAsync() creates the database on the first run and applies each schema change after that.