/// <summary>
/// Creates a new isolated application builder which gets its own <see cref="ServiceCollection"/>, which only
/// has the default services registered. It will not share the <see cref="ServiceCollection"/> from the
/// originating app.
/// </summary>
/// <param name="app">The application builder to create the isolated app from.</param>
/// <param name="configuration">The branch of the isolated app.</param>
/// <param name="registration">A method to configure the newly created service collection.</param>
/// <returns>The new pipeline with the isolated application integrated.</returns>
public static IApplicationBuilder Isolate(
this IApplicationBuilder app,
Action <IApplicationBuilder> configuration,
Func <IServiceCollection, IServiceProvider> registration)
{
var services = CreateDefaultServiceCollection(app.ApplicationServices);
var provider = registration(services);
var builder = new ApplicationBuilder(null);
builder.ApplicationServices = provider;
builder.Use(async(context, next) =>
{
var factory = provider.GetRequiredService <IServiceScopeFactory>();
// Store the original request services in the current ASP.NET context.
context.Items[typeof(IServiceProvider)] = context.RequestServices;
try
{
using (var scope = factory.CreateScope())
{
context.RequestServices = scope.ServiceProvider;
await next();
}
}
finally
{
context.RequestServices = null;
}
});
configuration(builder);
return(app.Use(next =>
{
// Run the rest of the pipeline in the original context,
// with the services defined by the parent application builder.
builder.Run(async context =>
{
var factory = app.ApplicationServices.GetRequiredService <IServiceScopeFactory>();
try
{
using (var scope = factory.CreateScope())
{
context.RequestServices = scope.ServiceProvider;
await next(context);
}
}
finally
{
context.RequestServices = null;
}
});
var branch = builder.Build();
return context => branch(context);
}));
}
