I am setting up my seed methods in my migration's configuration class.
I have added a reference to the following name spaces
using Microsoft.AspNet.Identity;
using Microsoft.AspNet.Identity.EntityFramework;
and wrote up the following method that gets called from the Seed method
private void SeedMembership(MyDbContext context)
{
var user = new ApplicationUser() { UserName = "demo"};
UserManager<ApplicationUser> userManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(context));
var result = UserManager.Create(user,"demo");
}
The idea was to have this aoto create a user with username=demo and password=demo
but I cant compile getting the following error:
using the generic type 'Microsoft.AspNet.Identity.UserManager<TUser>' requires 1 type argument
I am a bit stuck as to why.
Thanks!
You seem to have a typo:
var result = UserManager.Create(user,"demo");
You should use userManager, note the lower-case u.
Related
I've an error: "ExceptionMessage": "Self referencing loop detected for property 'Posto' with type 'UfficioServer.Posto'. Path '[0].Dipendente[0]'.",
when i call my web api, i need a list of Posti whit the association with Dipendente...
public List<Posto> GetAllPosti()
{
try
{
List<Posto> p = new List<Posto>();
UfficioPostiEntities1 db = new UfficioPostiEntities1();
db.Configuration.ProxyCreationEnabled = false;
var posto = db.Posto.Include("Dipendente").ToList();
var x = db.Posto.ToList();
return x;
}
can someone help me?
To avoid this error you should add the following to the Application_Start in Global.asax:
HttpConfiguration config = GlobalConfiguration.Configuration;
config.Formatters.JsonFormatter
.SerializerSettings
.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
This is because (as per documentation)
ReferenceLoopHandling.Ignore: Json.NET will ignore objects in
reference loops and not serialize them. The first time an object is
encountered it will be serialized as usual but if the object is
encountered as a child object of itself the serializer will skip
serializing it.
I have a method that receives an IEnumerable<Guid> of IDs to objects I want to delete. One suggested method is as follows
foreach(Guid id in ids)
{
var tempInstance = new MyEntity { Id = id };
DataContext.Attach(tempInstance); // Exception here
DataContext.Remove(tempInstance);
}
This works fine if the objects aren't already loaded into memory. But my problem is that when they are already loaded then the Attach method throws an InvalidOperationException - The instance of entity type 'MyEntity' cannot be tracked because another instance with the key value 'Id:...' is already being tracked. The same happens if I use DataContext.Remove without calling Attach.
foreach(Guid id in ids)
{
var tempInstance = new MyEntity { Id = id };
DataContext.Remove(tempInstance); // Exception here
}
I don't want to use DataContext.Find to grab the instance of an already loaded object because that will load the object into memory if it isn't already loaded.
I cannot use DataContext.ChangeTracker to find already loaded objects because only objects with modified state appear in there and my objects might be loaded and unmodified.
The following approach throws the same InvalidOperationException when setting EntityEntry.State, even when I override GetHashCode and Equals on MyEntity to ensure dictionary lookups see them as the same object.
foreach(Guid id in ids)
{
var tempInstance = new MyEntity { Id = id };
EntityEntry entry = DataContext.Entry(tempInstance);
entry.State == EntityState.Deleted; // Exception here
}
The only way so far I have found that I can achieve deleting objects by ID without knowing if the object is the following:
foreach(Guid id in ids)
{
var tempInstance = new MyEntity { Id = id };
try
{
DataContext.Attach(tempInstance); // Exception here
}
catch (InvalidOperationException)
{
}
DataContext.Remove(tempInstance);
}
It's odd that I am able to call DataContext.Remove(tempInstance) without error after experiencing an exception trying to Attach it, but at this point it does work without an exception and also deletes the correct rows from the database when DataContext.SaveChanges is executed.
I don't like catching the exception. Is there a "good" way of achieving what I want?
Note: If the class has a self-reference then you need to load the objects into memory so EntityFrameworkCore can determine in which order to delete the objects.
Strangely, although this is a quite common exception in EF6 and EF Core, neither of them expose publicly a method for programmatically detecting the already tracked entity instance with the same key. Note that overriding GetHashCode and Equals doesn't help since EF is using reference equality for tracking entity instances.
Of course it can be obtained from the DbSet<T>.Local property, but it would not be as efficient as the internal EF mechanism used by Find and the methods throwing the aforementioned exception. All we need is the first part of the Find method and returning null when not found instead of loading from the database.
Luckily, for EF Core the method that we need can be implemented relatively easily by using some of the EF Core internals (under the standard This API supports the Entity Framework Core infrastructure and is not intended to be used directly from your code. This API may change or be removed in future releases. policy). Here is the sample implementation, tested on EF Core 2.0.1:
using Microsoft.EntityFrameworkCore.Internal;
namespace Microsoft.EntityFrameworkCore
{
public static partial class CustomExtensions
{
public static TEntity FindTracked<TEntity>(this DbContext context, params object[] keyValues)
where TEntity : class
{
var entityType = context.Model.FindEntityType(typeof(TEntity));
var key = entityType.FindPrimaryKey();
var stateManager = context.GetDependencies().StateManager;
var entry = stateManager.TryGetEntry(key, keyValues);
return entry?.Entity as TEntity;
}
}
}
Now you can use simply:
foreach (var id in ids)
DataContext.Remove(DataContext.FindTracked<MyEntity>(id) ?? new MyEntity { Id = id }));
or
DataContext.RemoveRange(ids.Select(id =>
DataContext.FindTracked<MyEntity>(id) ?? new MyEntity { Id = id }));
After hours of struggling with MiniProfiler to make it profile the Database queries, I have no luck and I'm getting the error:
A null was returned after calling the 'get_ProviderFactory' method on
a store provider instance of type
'StackExchange.Profiling.Data.ProfiledDbConnection'. The store
provider might not be functioning correctly.
I got through many SO posts but nothing has worked so far, like this post which is about the same error but with different configuration and well there's not an answer. Now I know that ProfiledDbConnection is not overriding DbProviderFactory and it's parent class DbConnection returns null in it's implementation of DbProviderFactory so the error is expectable but it should work somehow. There is a MiniProfilerEF.Initialize() but it seams to be usable for CodeFirst only and I'm using DatabaseFirst approach.
I have installed MiniProfiler, MiniProfiler.EF, MiniProfilerMVC3 nuget packages. And here is my code:
string connectionString = ConfigurationManager.ConnectionStrings["SqlConnection"].ConnectionString;
var sqlConnection = new SqlConnection(connectionString);
var profiled = new ProfiledDbConnection(sqlConnection, MiniProfiler.Current);
var db = new DbContext(profiled, true);
db.Set<Customer>().ToList();
And I'm using asp.net mvc4, EF5, DatabseFirst, MiniProfiler 2.1.0.0, Sql Server
Any Idea?
So, coming from your comment on Setup of mvc-mini-profiler for EF-db- first, have you tried removing the Mini Profiler-specific wrapper?
var profiled = new ProfiledDbConnection(sqlConnection, MiniProfiler.Current);
var db = new DbContext(profiled, true);
db.Set<Customer>().ToList();
Instead, just adding
protected void Application_Start()
{
// any other code
MiniProfilerEF.Initialize();
}
and then doing standard db access?
using (var db = new WordsEntities()) {
var posts = db.Customer.Take(4);
// more code
}
Simplest example of this, I get a collection and try to output it via Web API:
// GET api/items
public IEnumerable<Item> Get()
{
return MyContext.Items.ToList();
}
And I get the error:
Object of type
'System.Data.Objects.ObjectQuery`1[Dcip.Ams.BO.EquipmentWarranty]'
cannot be converted to type
'System.Data.Entity.DbSet`1[Dcip.Ams.BO.EquipmentWarranty]'
This is a pretty common error to do with the new proxies, and I know that I can fix it by setting:
MyContext.Configuration.ProxyCreationEnabled = false;
But that defeats the purpose of a lot of what I am trying to do. Is there a better way?
I would suggest Disable Proxy Creation only in the place where you don't need or is causing you trouble. You don't have to disable it globally you can just disable the current DB context via code...
[HttpGet]
[WithDbContextApi]
public HttpResponseMessage Get(int take = 10, int skip = 0)
{
CurrentDbContext.Configuration.ProxyCreationEnabled = false;
var lista = CurrentDbContext.PaymentTypes
.OrderByDescending(x => x.Id)
.Skip(skip)
.Take(take)
.ToList();
var count = CurrentDbContext.PaymentTypes.Count();
return Request.CreateResponse(HttpStatusCode.OK, new { PaymentTypes = lista, TotalCount = count });
}
Here I only disabled the ProxyCreation in this method, because for every request there is a new DBContext created and therefore I only disabled the ProxyCreation for this case .
Hope it helps
if you have navigation properties and you do not want make them non virtual, you should using JSON.NET and change configuration in App_Start to using JSON not XML!
after install JSON.NET From NuGet, insert this code in WebApiConfig.cs in Register method
var json = config.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
config.Formatters.Remove(config.Formatters.XmlFormatter);
If you have navigation properties make them non virtual. Mapping will still work but it prevents the creation of Dynamic Proxy entities which cannot be serialized.]
Not having lazy loading is fine in a WebApi as you don't have a persistent connection and you ran a .ToList() anyway.
I just disabled proxy classes on a per needed basis:
// GET: ALL Employee
public IEnumerable<DimEmployee> Get()
{
using (AdventureWorks_MBDEV_DW2008Entities entities = new AdventureWorks_MBDEV_DW2008Entities())
{
entities.Configuration.ProxyCreationEnabled = false;
return entities.DimEmployees.ToList();
}
}
Add the following code in Application_Start function of Global.asax.cs:
GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings
.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
GlobalConfiguration.Configuration.Formatters
.Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter);
This instruct the API to serialize every response into JSON and remove XML responses.
In my case the object being returned had a property within it with a type that did not have an argumentless/default constructor. By adding a zero-argument constructor to that type the object could be serialized successfully.
I had the same problem and my DTO was missing an parameter less constructor.
public UserVM() { }
public UserVM(User U)
{
LoginId = U.LoginId;
GroupName = U.GroupName;
}
First constructor was missing.
I got this error message and it turns out the problem was that I had accidentally set my class to use the same serialized property name for two properties:
public class ResultDto
{
//...
[JsonProperty(PropertyName="DataCheckedBy")]
public string ActualAssociations { get; set; }
[JsonProperty(PropertyName="DataCheckedBy")]
public string ExpectedAssociations { get; set; }
//...
}
If you're getting this error and you aren't sending entities directly through your API, copy the class that's failing to serialize to LINQPad and just call JsonConvert.SerializeObject() on it and it should give you a better error message than this crap. As soon as I tried this it gave me the following error message: A member with the name 'DataCheckedBy' already exists on 'UserQuery+ResultDto'. Use the JsonPropertyAttribute to specify another name.
After disable Proxy Creation, use eager loading (Include()) to load the proxy object.
In my Project EntityCollection returned from the WebApi action method.
Configuration.ProxyCreationEnabled = false not applicable. I have tried the below approach it is working fine for me.
Control Panel.
2.Turn on Windows Features on or off
Choose Internet Information Service
Check all the World Wide Web Components it would be better to check all the components in IIS.
Install the components.
Go to (IIS) type inetmgr in command prompt.
select the published code in the Virtual directory.
Convert into application
Browse it the application.
The answer by #Mahdi perfectly fixes the issue for me, however what I noticed is that if my Newtonsoft.JSON is 11.0 version then it doesn't fix the issue, but the moment I update Newtonsoft.JSON to latest 13.0 it starts working.
Ok, I want to recreate a project that I created using EF 4.1 to EF 5.0, simple enough or at least I thought. One of the things in my old project is that I was able to change the database connection string at runtime in EF 4.1:
using (var myContext = new MyEntities(ConnectionString))
{
}
Easy-peasy but in EF 5.0 you have to do this differently:
string connectionString = "data source=LocalHost;initial catalog=MyDatabase;user id=MyUserName;password=MyPassword;multipleactiveresultsets=True;App=EntityFramework";
using (var myContext = new MyEntities())
{
myContext.Database.Connection.ConnectionString = connectionString;
}
Now, this took me a better part of two hours to figure out, so I guess my question is this the proper way of changing the connection string at runtime or not? If it is why did they make this change?
I did find this Link but it didn't work. I received the error as detailed in the first comment of the first answer by Ladislav Mrnka. I later found this Link which seems to work fine.
UPDATE
I re-read the first link I posted and I found another solution, I simply created a partial class:
public partial class MyEntities : DbContext
{
public MyEntities(string connectionString) : base(connectionString)
{
Database.Connection.ConnectionString = connectionString;
}
}
Use the context constructor overload that takes the connection string as a parameter.
Create a class with the same name as the Target ContextClass class next to the main class
like this :
public CustomerContext( string connectionString)
: base(connectionString)
{
}
For using :
using (var context = new CustomerContext("connectionString"))
{
}
Or
var customerContext=new CustomerContext("yorConnectionString");
var customer=CustomerContext.customer.FirstOrDefault(x=>x.id==1).FirstName;
Have a look at other link Setup Entity Framework For Dynamic Connection String.
It says - " you can do it by creating another partial class as the Entities class is declared partial"