I have been trying to get my head around async in asp.net core 3.0, but I am still missing something.
I have some async db queries:
public async Task<IList<MyObject>> GetAll(MyContext context)
{
var a = MyMethodA(context);
var b = MyMethodA(context);
return (await Task.WhenAll(a, b)).SelectMany(e => e).ToList();
}
index.cs:
public Task<IList<MyObject>> MyDBList { get; set; }
public void OnGet()
{
MyDBList = _myInterface.GetAll(context);
}
Index.cshml
foreach (var x in Model.MyDBList) {
<p>x.ID</p>
}
On index.cshtml I get the error System.Threading.Tasks.Task> cannot be used in 'foreach' statement because it neither implements 'IEnumerable' or 'IEnumerable', nor has suitable 'GetEnumerator'
It looks like you need to use an await on your call to your async function - like so:
public void OnGet()
MyDBList = await _myInterface.GetAll(context);
}
Related
I am working with ABP and I used the basic setup which is generated by the abp cli with EF Core and SQL Server.
Now, I would like to replace SQLite (the generated one), with a LocalDb database, since I using spatial data for unit- and integration testing.
However, I am not sure how to make the replacement. I have identified the file which initialize the SQLite, and it is reseeded after each unittest.
When switching to LocalDb, I will not flush / seed database, and I think I have solved that out.
This is the generated file ...\ABPProject\aspnet-core\ABPProject.EntityFrameworkCore.Tests\EntityFrameworkCore\ABPProjectEntityFrameworkCoreTestModule.cs that uses SQLite, can you please give me an example / ideas how to use LocalDb instead of SQLite?
[DependsOn(
typeof(ABPProjectEntityFrameworkCoreModule),
typeof(ABPProjectTestBaseModule),
typeof(AbpEntityFrameworkCoreSqliteModule)
)]
public class ABPProjectEntityFrameworkCoreTestModule : AbpModule
{
private SqliteConnection _sqliteConnection;
public override void ConfigureServices(ServiceConfigurationContext context)
{
ConfigureInMemorySqlite(context.Services);
}
private void ConfigureInMemorySqlite(IServiceCollection services)
{
_sqliteConnection = CreateDatabaseAndGetConnection();
services.Configure<AbpDbContextOptions>(options =>
{
options.Configure(context =>
{
context.DbContextOptions.UseSqlite(_sqliteConnection);
});
});
}
public override void OnApplicationShutdown(ApplicationShutdownContext context)
{
_sqliteConnection.Dispose();
}
private static SqliteConnection CreateDatabaseAndGetConnection()
{
var connection = new SqliteConnection("Data Source=:memory:");
connection.Open();
var options = new DbContextOptionsBuilder<ABPProjectDbContext>()
.UseSqlite(connection)
.Options;
using (var context = new ABPProjectDbContext(options))
{
context.GetService<IRelationalDatabaseCreator>().CreateTables();
}
return connection;
}
}
This was really simple. Just do this:
namespace ABPProject.EntityFrameworkCore;
[DependsOn(
typeof(ABPProjectEntityFrameworkCoreModule),
typeof(ABPProjectTestBaseModule),
typeof(AbpEntityFrameworkCoreSqliteModule)
)]
public class ABPProjectEntityFrameworkCoreTestModule : AbpModule
{
private SqliteConnection _sqliteConnection;
public override void ConfigureServices(ServiceConfigurationContext context)
{
//ConfigureInMemorySqlite(context.Services);
ConfigureLocalDb(context.Services);
}
private void ConfigureInMemorySqlite(IServiceCollection services)
{
_sqliteConnection = CreateDatabaseAndGetConnection_Sqlite();
services.Configure<AbpDbContextOptions>(options =>
{
options.Configure(context =>
{
context.DbContextOptions.UseSqlite(_sqliteConnection);
});
});
}
private void ConfigureLocalDb(IServiceCollection services)
{
services.Configure<AbpDbContextOptions>(options =>
{
options.Configure(context =>
{
context.DbContextOptions.UseSqlServer("Server=(LocalDb)\\MSSQLLocalDB;Database=ABPProject_Unittest;Trusted_Connection=True;TrustServerCertificate=True");
});
});
}
public override void OnApplicationShutdown(ApplicationShutdownContext context)
{
if (_sqliteConnection is not null)
{
_sqliteConnection.Dispose();
}
}
private static SqliteConnection CreateDatabaseAndGetConnection_Sqlite()
{
var connection = new SqliteConnection("Data Source=:memory:");
connection.Open();
var options = new DbContextOptionsBuilder<ABPProjectDbContext>()
.UseSqlite(connection, x => x.UseNetTopologySuite())
.Options;
using (var context = new ABPProjectDbContext(options))
{
context.GetService<IRelationalDatabaseCreator>().CreateTables();
}
return connection;
}
}
Then you need to disable re-seeding each time between test in aspnet-core\test\ABPProject.TestBase\ABPProjectTestBaseModule.cs
public override void OnApplicationInitialization(ApplicationInitializationContext context)
{
//SeedTestData(context);
}
How to reset the database when starting all tests? Use XUnit collections, which enable setup before all tests are starting and teardown after all tests are executed.
You can read more about it here https://xunit.net/docs/shared-context but basically, you create a new class (NOTE! You need to place this file in each test project, since the class can not be shared between different test projects):
public class DatabaseFixture : ABPProjectTestBase<ABPProjectEntityFrameworkCoreTestModule>, IAsyncLifetime
{
// ... create your shared vars here
public DatabaseFixture()
{
}
public async Task InitializeAsync()
{
IDbContextProvider<ABPProjectDbContext> _dbContextProvider = GetRequiredService<IDbContextProvider<ABPProjectDbContext>>();
IUnitOfWorkManager _unitOfWorkManager = GetRequiredService<IUnitOfWorkManager>();
IDataSeeder _dataSeeder = GetRequiredService<IDataSeeder>();
using (var uow = _unitOfWorkManager.Begin())
{
var context = await _dbContextProvider.GetDbContextAsync();
var tableNames = context.Model.GetEntityTypes()
.Where(t => t.GetTableName().StartsWith("App"))
.Select(t => t.GetTableName())
.Distinct()
.ToList();
// Disable constraints
foreach (var tableName in tableNames)
{
await context.Database.ExecuteSqlRawAsync($"ALTER TABLE {tableName} NOCHECK CONSTRAINT ALL");
}
// Remove rows
foreach (var tableName in tableNames)
{
await context.Database.ExecuteSqlRawAsync($"DELETE FROM {tableName}");
}
// Re-enable constraints
foreach (var tableName in tableNames)
{
await context.Database.ExecuteSqlRawAsync($"ALTER TABLE {tableName} CHECK CONSTRAINT ALL");
}
}
// Re - seed database
await _dataSeeder.SeedAsync();
}
public async Task DisposeAsync()
{
// ... clean up test data from the database with and use async calls here...
}
}
[CollectionDefinition("Database collection")]
public class DatabaseCollection : ICollectionFixture<DatabaseFixture>
{
// This class has no code, and is never created. Its purpose is simply
// to be the place to apply [CollectionDefinition] and all the
// ICollectionFixture<> interfaces.
}
The last thing is to decorate each test class with following:
namespace ABPProject.Things
{
[Collection("Database collection")]
public class ThingAppService_Tests : ABPProjectApplicationTestBase
{
public readonly DatabaseFixture _fixture;
private readonly IThingAppService _thingAppService;
public ThingAppService_Tests(DatabaseFixture fixture)
{
_fixture = fixture;
_thingAppService = GetRequiredService<IThingAppService>();
}
[Fact]
public async Task GetListAsync_Should_Get_all_Things()
{
// This is a test
}
}
}
I created a .net core web api project. It has gotten kinda big and I want to program a "delete" operation which deletes a lot of stuff from the database. Since there are a lot of things to delete, this will be a long running process. So I thought maybe I can run this in the background and just write status updates somewhere for the user to see whats happening.
I googled this and I found BackgroundWorkerQueue and thought this might be my solution.
So I registered the service and everything and here is my method that calls it:
public class DeleteController : ControllerBase {
private readonly BackgroundWorkerQueue _backgroundWorkerQueue;
public AdminController(BackgroundWorkerQueue backgroundWorkerQueue){
_backgroundWorkerQueue = backgroundWorkerQueue;
}
public async Task<ActionResult> HugeDeleteMethod(int id)
{
// some prechecks here...
// and here I thought I'd start the background task
_backgroundWorkerQueue.QueueBackgroundWorkItem(async token =>
{
var a = _context.StatusTable.Find(id);
a.Status += "Blablablabla\n";
_context.StatusTable.Update(a);
await _context.SaveChangesAsync();
//now start doing delete operations
});
}
}
And that class looks like this:
public class BackgroundWorkerQueue
{
private ConcurrentQueue<Func<CancellationToken, Task>> _workItems = new ConcurrentQueue<Func<CancellationToken, Task>>();
private SemaphoreSlim _signal = new SemaphoreSlim(0);
public async Task<Func<CancellationToken, Task>> DequeueAsync(CancellationToken cancellationToken)
{
await _signal.WaitAsync(cancellationToken);
_workItems.TryDequeue(out var workItem);
return workItem;
}
public void QueueBackgroundWorkItem(Func<CancellationToken, Task> workItem)
{
if (workItem == null)
{
throw new ArgumentNullException(nameof(workItem));
}
_workItems.Enqueue(workItem);
_signal.Release();
}
}
There is also a DeleteService, which is also called in my startup, but I am not sure what it does:
public class DeleteService : BackgroundService
{
private readonly BackgroundWorkerQueue queue;
public NukeService(BackgroundWorkerQueue queue)
{
this.queue = queue;
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
while (!stoppingToken.IsCancellationRequested)
{
var workItem = await queue.DequeueAsync(stoppingToken);
await workItem(stoppingToken);
}
}
}
Both are added in my startup.cs:
services.AddHostedService<DeleteService>();
services.AddSingleton<BackgroundWorkerQueue>();
Well, maybe I'm going about this all wrong. This is never called it seems, the StatusTable field "Status" is always empty. So how do I do this?
You just need to subclass BackgroundService class or implement IHostedService and than register your service as hosted service.
This will run a service in the background. Than in your service you can leverage the BlockingQueue that will perform tasks only when they are added, e.g. like this:
public class MyService : BackgroundService {
private readonly BlockingCollection<long> queue;
public MyService(){
this.queue = new BlockingCollection<long>();
Task.Run(async () => await this.Execute());
}
public void AddId(long id) {
this.queue.Add(id);
}
private async Task Execute()
{
foreach (var id in this.queue.GetConsumingEnumerable())
{
... do your stuff ...
}
}
}
services.AddHostedService<MyService>();
Here is the docu: Background services in .net core
I have a little problem. But I dont know why it doesnt work. And I dont know how to post all ids by postman.
I am using unit of work with generic repository. I want to send int[] ids to my controller. I dont want to send entity. I searched a lot it today. And I changed my code. But what is problem now?
This is my repostiroy:
public async Task DeleteRangeAsync(Expression<Func<T, bool>> predicate)
{
IQueryable<T> query = _dbSet.Where(predicate);
await Task.Run(() => { _dbSet.RemoveRange(query.AsNoTracking()); });
}
This is my KulturManager:
public async Task<IResult> HardDeleteRangeAsync(int[] ids)
{
await UnitOfWork.Kulturs.DeleteRangeAsync(c => ids.Contains(c.Id));
await UnitOfWork.SaveAsync();
return new Result(ResultStatus.Success, Messages.Info("Kultur", "HardDelete"));
}
And this is my KulturController:
[HttpDelete("{ids}")]
public async Task<IActionResult> HardDeleteRangeAsync(int[] ids)
{
var result = await _kulturManager.HardDeleteRangeAsync(ids);
return Ok(result.Message);
}
Thank you for help
You shouldn't fetch all the entities you want to delete. Instead create stub entities for RemoveRange. If you don't have a common base class, this requires reflection, but with a common entity base class you can do it like this:
public void DeleteRange<T>(int[] ids) where T: BaseEntity, new()
{
_dbSet.RemoveRange(ids.Select(i => new T() { Id = i }).ToList());
}
or if the method is in a generic class, the method would look like
public void DeleteRange(int[] ids)
{
_dbSet.RemoveRange(ids.Select(i => new T() { Id = i }).ToList());
}
And there's no reason to mark this as Async now since it doesn't do any database access.
I'm considering re-rewriting some of my MVC controllers to be async controllers. I have working unit tests for these controllers, but I'm trying to understand how to maintain them in an async controller environment.
For example, currently I have an action like this:
public ContentResult Transaction()
{
do stuff...
return Content("result");
}
and my unit test basically looks like:
var result = controller.Transaction();
Assert.AreEqual("result", result.Content);
Ok, that's easy enough.
But when your controller changes to look like this:
public void TransactionAsync()
{
do stuff...
AsyncManager.Parameters["result"] = "result";
}
public ContentResult TransactionCompleted(string result)
{
return Content(result);
}
How do you suppose your unit tests should be built? You can of course invoke the async initiator method in your test method, but how do you get at the return value?
I haven't seen anything about this on Google...
Thanks for any ideas.
As with any async code, unit testing needs to be aware of thread signalling. .NET includes a type called AutoResetEvent which can block the test thread until an async operation has been completed:
public class MyAsyncController : Controller
{
public void TransactionAsync()
{
AsyncManager.Parameters["result"] = "result";
}
public ContentResult TransactionCompleted(string result)
{
return Content(result);
}
}
[TestFixture]
public class MyAsyncControllerTests
{
#region Fields
private AutoResetEvent trigger;
private MyAsyncController controller;
#endregion
#region Tests
[Test]
public void TestTransactionAsync()
{
controller = new MyAsyncController();
trigger = new AutoResetEvent(false);
// When the async manager has finished processing an async operation, trigger our AutoResetEvent to proceed.
controller.AsyncManager.Finished += (sender, ev) => trigger.Set();
controller.TransactionAsync();
trigger.WaitOne()
// Continue with asserts
}
#endregion
}
Hope that helps :)
I've written short AsyncController extension method that simplifies unit testing a bit.
static class AsyncControllerExtensions
{
public static void ExecuteAsync(this AsyncController asyncController, Action actionAsync, Action actionCompleted)
{
var trigger = new AutoResetEvent(false);
asyncController.AsyncManager.Finished += (sender, ev) =>
{
actionCompleted();
trigger.Set();
};
actionAsync();
trigger.WaitOne();
}
}
That way we can simply hide threading 'noise':
public class SampleAsyncController : AsyncController
{
public void SquareOfAsync(int number)
{
AsyncManager.OutstandingOperations.Increment();
// here goes asynchronous operation
new Thread(() =>
{
Thread.Sleep(100);
// do some async long operation like ...
// calculate square number
AsyncManager.Parameters["result"] = number * number;
// decrementing OutstandingOperations to value 0
// will execute Finished EventHandler on AsyncManager
AsyncManager.OutstandingOperations.Decrement();
}).Start();
}
public JsonResult SquareOfCompleted(int result)
{
return Json(result);
}
}
[TestFixture]
public class SampleAsyncControllerTests
{
[Test]
public void When_calling_square_of_it_should_return_square_number_of_input()
{
var controller = new SampleAsyncController();
var result = new JsonResult();
const int number = 5;
controller.ExecuteAsync(() => controller.SquareOfAsync(number),
() => result = controller.SquareOfCompleted((int)controller.AsyncManager.Parameters["result"]));
Assert.AreEqual((int)(result.Data), number * number);
}
}
If you want to know more I've written a blog post about how to Unit test ASP.NET MVC 3 asynchronous controllers using Machine.Specifications
Or if you want to check this code it's on a github
I'm developing modular application and I'd like for entities from different modules to be able to register their own friendly url slugs.
app.UseMvc(routes =>
{
routes.Routes.Add(new SlugRouter(routes.DefaultHandler));
(...)
});
But following code throws Cannot access a disposed object. Object name: 'CommerceDbContext'. when trying to access slug from the repository.
public class SlugRouter : IRouter
{
private readonly IRouter _target;
public SlugRouter(IRouter target)
{
_target = target;
}
public async Task RouteAsync(RouteContext context)
{
var slugRepository = context.HttpContext.RequestServices.GetService<IRepository<SlugEntity>>();
// ERROR: Cannot access a disposed object. Object name: 'CommerceDbContext'
var urlSlug = await slugRepository.GetAllIncluding(x => x.EntityType).FirstOrDefaultAsync(x => x.Slug == context.HttpContext.Request.Path.Value);
(...)
}
It must be something simple I'm missing to be able to access the repository from router. Thanks for any help.
Begin a unit of work:
public async Task RouteAsync(RouteContext context)
{
var slugRepository = context.HttpContext.RequestServices.GetService<IRepository<SlugEntity>>();
var unitOfWorkManager = context.HttpContext.RequestServices.GetService<IUnitOfWorkManager>();
using (var uow = unitOfWorkManager.Begin())
{
var urlSlug = await slugRepository.GetAllIncluding(x => x.EntityType).FirstOrDefaultAsync(x => x.Slug == context.HttpContext.Request.Path.Value);
await uow.CompleteAsync();
}
}
Access IModel. You do not need dbContext for.
for entities from different modules to be able to register their own
friendly url slugs
I do it this way:
1) move OnModelCreating to static methiod
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
BuildModel(modelBuilder);
}
public static void BuildModel(ModelBuilder modelBuilder)
{
// ...
}
2) Create model where you need:
var conventionSet = new ConventionSet();
var modelBuilder = new ModelBuilder(conventionSet);
AdminkaDbContext.BuildModel(modelBuilder);
var mutableModel = modelBuilder.Model;
There is your meta (in mutableModel ). You can loop through entities (types of entities).