Context
I have a model for representing comments that looks like the following:
public class Comment
{
public int Id { get; set; }
public int CommentId { get; set; } // Id of parent comment
...
}
In my DetailsModel class which is a subclass of PageModel, I have the following method for finding replies to a given comment:
public IList<Comment> Replies(int comment_id) =>
_context.Comment.Where(comment => comment.CommentId == comment_id).ToListAsync().Result;
I use it from a Razor page as follows:
Model.Replies(reply.Id).Count
This works fine.
More object-oriented approach?
In a more traditional object-oriented design, Replies might be a method on Comment. So finding the replies would look like this:
reply.Replies()
Moving the Replies method into Comment, we get:
public class Comment
{
public int Id { get; set; }
public int CommentId { get; set; } // Id of parent comment
...
public async Task<IList<Comment>> Replies()
{
return await _context.Comment.Where(comment => comment.CommentId == Id).ToListAsync();
}
}
And now you can see the issue; Comment now has a dependency on the DbContext, which seems like a very odd arrangement.
So my question is, is there a way to get Replies to be a method on Comment in a way that's idiomatic for ASP.NET Core / EF Core?
UPDATE - CommentAlt
Here's one approach I've explored.
I have a CommentAlt class.
It is a subclass of Comment (so as to inherit all the fields from Comment).
The constructor accepts a BasePageModel.
My page models inherit from BasePageModel.
BasePageModel gives CommentAlt access to things like
DbContext
UserManager<IdentityUser>
AuthorizationService
Here's CommentAlt:
public class CommentAlt : Comment
{
private BasePageModel Model { get; }
public CommentAlt(Comment comment, BasePageModel model)
{
Id = comment.Id;
CommentId = comment.CommentId;
...
Model = model;
}
public IList<CommentAlt> Replies() =>
Model.Context.Comment
.Where(comment => comment.CommentId == Id).ToList()
.Select(elt => new CommentAlt(elt, Model)).ToList();
...
}
As you can see, now Replies is a method on it. In one of my Razor pages, I have the following expression:
#if (reply.Replies().Count > 0)
and it works fine.
Here's my BasePageModel which is passed to the CommentAlt contructor:
public class BasePageModel : PageModel
{
public ApplicationDbContext Context { get; }
public IAuthorizationService AuthorizationService { get; }
public UserManager<IdentityUser> UserManager { get; }
public BasePageModel(
ApplicationDbContext context,
IAuthorizationService authorizationService,
UserManager<IdentityUser> userManager) : base()
{
Context = context;
UserManager = userManager;
AuthorizationService = authorizationService;
}
}
One thing I feel a little weird about is having the Context, AuthorizationService, and UserManager properties here be public. I changed them to public so that ConmmentAlt would have access to them.
Is the approach taken here with CommentAlt recommended? Is there a better way?
Related
We have an API with about a dozen integration tests. All the tests passed until I added some DTOs and used AutoMapper. Now, all the tests that test methods that use AutoMapper and the DTOs are failing. I have provided all the code needed to understand one of the failing tests. Also, I read a lot about AutoMapper and the following StackOverflow posts:
Integration Testing with AutoMapper fails to initialise configuration
A kind of integration testing in ASP.NET Core, with EF and AutoMapper
Startup.cs
This is our Startup.ConfigureServices(). I have tried every code block commented out and/or marked "ATTEMPTED".
public void ConfigureServices(IServiceCollection services)
{
services
.AddDbContext<OurContext>(options =>
options.UseSqlServer(Configuration["ConnectionString"]))
.AddDbContext<OurContext>()
.AddRazorPages()
.AddMvcOptions(options => options.EnableEndpointRouting = false)
.AddNewtonsoftJson(options => options.SerializerSettings.ContractResolver = new DefaultContractResolver());
services
.AddControllersWithViews();
//ATTEMPTED
//services
// .AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());
//ATTEMPTED
//MapperConfiguration mapperConfiguration = new MapperConfiguration(mc =>
//{
// mc.AddProfile(new OurProfile());
//});
//IMapper mapper = mapperConfiguration.CreateMapper();
//services
// .AddSingleton(mapper);
//ATTEMPTED
//services
// .AddAutoMapper(typeof(Startup));
//ATTEMPTED
//var assembly = typeof(Program).GetTypeInfo().Assembly;
//services
// .AddAutoMapper(assembly);
//ATTEMPTED
var assembly = typeof(Program).GetTypeInfo().Assembly;
services.AddAutoMapper(cfg =>
{
cfg.AllowNullDestinationValues = true;
cfg.CreateMap<OurModel, OurDto>()
.IgnoreAllPropertiesWithAnInaccessibleSetter();
}, assembly);
}
Controller
This is our controller.
[Route("api/[controller]")]
[ApiController]
public class OurController : ControllerBase
{
private readonly OurContext _context;
protected readonly ILogger<OurController> Logger;
private readonly IMapper _mapper;
public OurController(OurContext context, ILogger<OurController> logger,
IMapper mapper)
{
_context = context ??
throw new ArgumentNullException(nameof(context));
Logger = logger ??
throw new ArgumentNullException(nameof(logger));
_mapper = mapper ??
throw new ArgumentNullException(nameof(mapper));
}
[HttpGet]
public async Task<ActionResult<IEnumerable<OurDto>>> GetAll()
{
IQueryable<OurModel> models = _context.OurModel;
IQueryable<OurDto> dtos =
_mapper.Map<IQueryable<OurDto>>(models);
return await dtos.ToListAsync();
}
}
Profile, Model, and DTO
Profile
public class OurProfile : Profile
{
public OurProfile()
{
CreateMap<OurModel, OurDto>();
}
}
Model
public partial class OurModel
{
public string Number { get; set; }
public string Name1 { get; set; }
public string Name2 { get; set; }
public string Status { get; set; }
public DateTime? Date { get; set; }
public string Description { get; set; }
public string Comment { get; set; }
public string District { get; set; }
}
DTO
public class OurDto
{
public string Number { get; set; }
public string Name1 { get; set; }
public string Name2 { get; set; }
public string Status { get; set; }
public DateTime? Date { get; set; }
public string Description { get; set; }
public string Comment { get; set; }
public string District { get; set; }
}
Test Fixture
This is our test fixture.
public abstract class ApiClientFixture : IClassFixture<WebApplicationFactory<Startup>>
{
private readonly WebApplicationFactory<Startup> _factory;
protected abstract string RelativeUrl { get; }
protected ApiClientFixture(WebApplicationFactory<Startup> factory)
{
_factory = factory;
}
protected HttpClient CreateClient()
{
HttpClient client;
var builder = new UriBuilder();
client = _factory.CreateClient();
builder.Host = client.BaseAddress.Host;
builder.Path = $"{RelativeUrl}";
client.BaseAddress = builder.Uri;
return client;
}
}
Test
This is our test class. The single test in this test class fails.
public class Tests : ApiClientFixture
{
public Tests(WebApplicationFactory<Startup> factory) : base(factory)
{
}
protected override string RelativeUrl => "api/OurController/";
[Fact]
public async void GetAllReturnsSomething()
{
var response = await CreateClient().GetAsync("");
Assert.True(response.IsSuccessStatusCode);
}
}
When I debug the test I see that a 500 status code is returned from the URL provided to the in-memory API.
Does anybody have some suggestions? More than half of our tests currently fail, and I suspect that AutoMapper is not configured properly for integration testing.
Creating a map for IQueryable<T> is not really a good solution. In your answer you are losing proper flow of asynchronous database querying. I wrote about IQueryable<T> in a comment because you were looking for a 500 error cause. Making it work it's a one thing, making it a good solution it's another thing, however.
I'd strongly suggest to use AutoMapper ProjectTo() extension which you can use directly on a IQueryable<T> sequence. It let's you combine mapping and querying in one go. More or less it does a Select() based on your mappings, so it not only gives you proper model right away with the query result, but it also reduces the amount of columns obtained from database, which can make the query run faster. But, there are of course limitations to it, e.g. you can't use custom type converters or conditional mapping. You can read more about Project() in the documentation.
Usage:
public async Task<ActionResult<List<OurDto>>> GetAll()
{
return await _context
.OurModel
.ProjectTo<OutDto>(_mapper.ConfigurationProvider)
.ToListAsync();
}
Thanks to #Prolog for his comment. I realized that I need to map each element of the IQueryable individually, so I rewrote my Controller method.
Also, side note: IList.AsQueryable().ToListAsync() does not work, so I wrote:
IQueryable<OurDto> dtosQueryable = dtos.AsQueryable();
return await Task.FromResult(dtosQueryable.ToList());
Old Controller Method
[HttpGet]
public async Task<ActionResult<IEnumerable<OurDto>>> GetAll()
{
IQueryable<OurModel> models = _context.OurModel;
IQueryable<OurDto> dtos =
_mapper.Map<IQueryable<OurDto>>(models);
return await dtos.ToListAsync();
}
New Controller Method
public async Task<ActionResult<IEnumerable<OurDto>>> GetAll()
{
IQueryable<OurModel> models = _context.OurModel;
IList<OurDto> dtos = new List<OurDto>();
foreach (OurModel model in models)
{
OurDto dto = _mapper.Map<OurDto>(model);
dtos.Add(dto);
}
IQueryable<OurDto> dtosQueryable = dtos.AsQueryable();
return await Task.FromResult(dtosQueryable.ToList());
}
I m new in .net core 2.1
I m working with .net core 2.1 with code first approach
issue is when I create a new object dbcontext class then give error see below line
dbcontextstudent db=new dbcontextstudent(); //here give an red line
appsettings.json
},
"ConnectionStrings": {
"sqlserverconn": "Server=DEVISSHAHID; Database=studdbs; User id=xxxx;Password=xxxxx;"
},
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
//connection string
services.AddDbContext<DbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("sqlserverconn")));
student.cs
namespace WebApplication1.Models
{
public class student
{
[Key]
public int studid { get; set; }
public string studname { get; set; }
public string studsalary { get; set; }
public int studage { get; set; }
}
}
dbcontextstudent.cs
namespace WebApplication1.Models
{
public class dbcontextstudent : DbContext
{
public dbcontextstudent(DbContextOptions<dbcontextstudent> options) : base(options)
{
}
public DbSet<student> stud { get; set; }
}
}
HomeController.cs
I m not understood the above intellisense
I write the code as per intellisense but still give an error I know error is clear but not solved
which place doing I m wrong?
You will have to pass your DbContext type to the AddDbContext method in ConfigureServices method like this:
services.AddDbContext<dbcontextstudent>(options => options.UseSqlServer(Configuration.GetConnectionString("sqlserverconn")));
After that, you have registered the dbcontextstudent class in dependency injection.
You shouldn't create the instance of dbcontextstudent on your own like you did:
dbcontextstudent db=new dbcontextstudent();
Instead you can inject it though the constructor of your controller like this:
public HomeController : Controller
{
private readonly dbcontextstudent _db;
public HomeController(dbcontextstudent db)
{
_db = db;
}
... and then you can use the _db variable in your post action
}
I looking for some help on how to implement IN clause in the repository pattern. Rather than making single call for each and every record, I will have set of IDs, pass on this IDs to Context to get entities which satisfies the condition using Repository Pattern with EF.
I knew we can have something like this:
context.Students.Where( x => StudentIDs.contains(x.ID))
How to implement same in the repository layer or pattern with single call to DB?
If you really are a purist, yes you should abstract the DbContext entirely as you seem to imply.
I'm not sure I completely understand the issue, but something like that should do the job:
namespace EFRepo
{
class Student
{
public long Id { get; set; }
public string Name { get; set; }
}
class SchoolContext : DbContext
{
public DbSet<Student> Students { get; set; }
}
class SchoolRepository
{
private SchoolContext context = new SchoolContext();
public Student Add(string name)
{
Student student = new Student { Name = name };
context.Students.Add(student);
context.SaveChanges();
return student;
}
public IEnumerable<Student> GetStudentsByIds(IEnumerable<long> ids)
{
return context.Students.Where(x => ids.Contains(x.Id));
}
}
class Program
{
static void Main(string[] args)
{
SchoolRepository repo = new SchoolRepository();
repo.Add("Bully");
repo.Add("Crawler");
repo.Add("Tart");
foreach (Student s in repo.GetStudentsByIds(new[] { 1L, 3 }))
{
Console.WriteLine(s.Name);
}
}
}
}
I have the following Entity class definition:
[Table("Users")]
public class WebUser
{
public virtual int Id { get; set; }
public virtual ICollection<Client> Clients { get; set; }
// more properties...
}
Notice that table name is different than the class name. I also have a ClientUsers table which is a many-to-many mapping for clients and users. Problem is, when I try to access the webUser.Clients property I get the following exception:
"Invalid object name 'dbo.ClientWebUsers'."
Looks like Entity Framework is trying to guess the name of the third table, but it apparently was not smart enough to take into account the table attribute that I have there. How can I tell EF that it is ClientUsers and not ClientWebUsers? Also what rule does it follow to know which table name comes first and which one comes second in the new table name? I think it's not alphabetical order.
I'm using EF 5.0. Thanks!
From the looks of things you're using Code First, so I'll answer accordingly. If this is incorrect, please let me know.
I believe the convention being used to determine the name of the many-to-many table is determined by the order in which they occur as DbSet properties in your SomeContext : DbContext class.
As for forcing EntityFramework to name your table whatever you like, you can use the Fluent API in the OnModelCreating method of your SomeContext : DbContext class as follows:
public class DatabaseContext : DbContext
{
public DatabaseContext()
: base("SomeDB")
{
}
public DbSet<WebUser> Users { get; set; }
public DbSet<Client> Clients { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<WebUser>().HasMany(c => c.Clients)
.WithMany(p => p.WebUsers).Map(
m =>
{
m.MapLeftKey("ClientId");
m.MapRightKey("UserId");
m.ToTable("ClientUsers");
});
}
}
This assumes your classes are something like the following:
[Table("Users")]
public class WebUser
{
public virtual int Id { get; set; }
public virtual ICollection<Client> Clients { get; set; }
// more properties...
}
public class Client
{
public int Id { get; set; }
public ICollection<WebUser> WebUsers { get; set; }
// more properties
}
Finally, here's an integration test (NUnit) demonstrating the functionality working. You may need to drop your database before running it as Code First should want to update/migrate/recreate it.
[TestFixture]
public class Test
{
[Test]
public void UseDB()
{
var db = new DatabaseContext();
db.Users.Add(new WebUser { Clients = new List<Client> { new Client() } });
db.SaveChanges();
var webUser = db.Users.First();
var client = webUser.Clients.FirstOrDefault();
Assert.NotNull(client);
}
}
Edit: Link to relevant documentation for the Fluent API
Rowan's answer (adding here for reference):
Here is the information on how to configure a many-to-many table (including specifying the table name). The code you are after is something like:
modelBuilder.Entity<WebUser>()
.HasMany(u => u.Clients)
.WithMany(c => c.WebUsers)
.Map(m => m.ToTable("ClientUsers");
~Rowan
I've got a ValidationAttribute that looks like this:
public class RegistrationUniqueNameAttribute : ValidationAttribute
{
public IRepository<User> UserRepository { get; set; }
public override bool IsValid(object value)
{
//use UserRepository here....
}
}
In my container setup (in app start) I have this:
builder.Register(c => new RegistrationUniqueEmailAttribute
{
UserRepository = c.Resolve<IRepository<User>>()
});
However, when debugging, the value of UserRepository is always null, so the property isn't getting injected.
Have I set up my container wrong?
I'd really rather not have to use DependencyResolver.Current.GetService<IRepository<User>>() as this isn't as testable...
No, Autofac v3 doesn't do anything special with ValidationAttribute and friends [Autofac.Mvc does lots of powerful things e.g., with filter attributes].
I solved the problem indirectly in this answer, enabling one to write:
class MyModel
{
...
[Required, StringLength(42)]
[ValidatorService(typeof(MyDiDependentValidator), ErrorMessage = "It's simply unacceptable")]
public string MyProperty { get; set; }
....
}
public class MyDiDependentValidator : Validator<MyModel>
{
readonly IUnitOfWork _iLoveWrappingStuff;
public MyDiDependentValidator(IUnitOfWork iLoveWrappingStuff)
{
_iLoveWrappingStuff = iLoveWrappingStuff;
}
protected override bool IsValid(MyModel instance, object value)
{
var attempted = (string)value;
return _iLoveWrappingStuff.SaysCanHazCheez(instance, attempted);
}
}
(And some helper classes inc wiring to ASP.NET MVC...)