The instance of entity type cannot be tracked because another instance of this type with the same key is already being tracked

Question

I have a Service Object Update   public bool Update object original  object modified        var originalClient    Client original      var modifiedClient    Client modified       context Clients Update originalClient      lt -- throws the error      context SaveChanges          Variance checking and logging of changes between the modified and original     This is where I am calling this method from   public IActionResult Update DetailViewModel vm        var originalClient    Client  service GetAsNoTracking vm ClientId       var modifiedClient    Client  service Fetch vm ClientId ToString            Changing the modifiedClient here      service Update originalClient  modifiedClient       Here is the GetAsNotTracking method   public Client GetAsNoTracking long id        return GetClientQueryableObject id  AsNoTracking   FirstOrDefault        Fetch method   public object Fetch string id       long fetchId     long TryParse id  out fetchId      return GetClientQueryableObject fetchId  FirstOrDefault        GetClientQueryableObject   private Microsoft Data Entity Query IIncludableQueryable lt Client  ActivityType gt  GetClientQueryableObject long searchId        return  context Clients          Where x   gt  x Id    searchId           Include x   gt  x Opportunities           ThenInclude x   gt  x BusinessUnit           Include x   gt  x Opportunities           ThenInclude x   gt  x Probability           Include x   gt  x Industry           Include x   gt  x Activities           ThenInclude x   gt  x User           Include x   gt  x Activities           ThenInclude x   gt  x ActivityType        Any ideas   I have looked the following articles   discussions  To no avail ASP NET GitHub Issue 3839  UPDATE   Here are the changes to GetAsNoTracking   public Client GetAsNoTracking long id        return GetClientQueryableObjectAsNoTracking id  FirstOrDefault        GetClientQueryableObjectAsNoTracking   private IQueryable lt Client gt  GetClientQueryableObjectAsNoTracking long searchId        return  context Clients          Where x   gt  x Id    searchId           Include x   gt  x Opportunities           ThenInclude x   gt  x BusinessUnit           AsNoTracking            Include x   gt  x Opportunities           ThenInclude x   gt  x Probability           AsNoTracking            Include x   gt  x Industry           AsNoTracking            Include x   gt  x Activities           ThenInclude x   gt  x User           AsNoTracking            Include x   gt  x Activities           ThenInclude x   gt  x ActivityType           AsNoTracking

User · Answer

Arhhh this got me and I spent a lot of time troubleshooting it. The problem was my tests were being executed in Parellel (the default with XUnit).

To make my test run sequentially I decorated each class with this attribute:

[Collection("Sequential")]

This is how I worked it out: Execute unit tests serially (rather than in parallel)

I mock up my EF In Memory context with GenFu:

private void CreateTestData(TheContext dbContext)
{
    GenFu.GenFu.Configure<Employee>()
       .Fill(q => q.EmployeeId, 3);
    var employee = GenFu.GenFu.ListOf<Employee>(1);

    var id = 1;
    GenFu.GenFu.Configure<Team>()
        .Fill(p => p.TeamId, () => id++).Fill(q => q.CreatedById, 3).Fill(q => q.ModifiedById, 3);
    var Teams = GenFu.GenFu.ListOf<Team>(20);
    dbContext.Team.AddRange(Teams);

    dbContext.SaveChanges();
}

When Creating Test Data, from what I can deduct, it was alive in two scopes (once in the Employee's Tests while the Team tests were running):

public void Team_Index_should_return_valid_model()
{
    using (var context = new TheContext(CreateNewContextOptions()))
    {
        //Arrange
        CreateTestData(context);
        var controller = new TeamController(context);

        //Act
        var actionResult = controller.Index();

        //Assert
        Assert.NotNull(actionResult);
        Assert.True(actionResult.Result is ViewResult);
        var model = ModelFromActionResult<List<Team>>((ActionResult)actionResult.Result);
        Assert.Equal(20, model.Count);
    }
}

Wrapping both Test Classes with this sequential collection attribute has cleared the apparent conflict.

[Collection("Sequential")]

Additional references:

https://github.com/aspnet/EntityFrameworkCore/issues/7340
EF Core 2.1 In memory DB not updating records
http://www.jerriepelser.com/blog/unit-testing-aspnet5-entityframework7-inmemory-database/
http://gunnarpeipman.com/2017/04/aspnet-core-ef-inmemory/
https://github.com/aspnet/EntityFrameworkCore/issues/12459
Preventing tracking issues when using EF Core SqlLite in Unit Tests

User · Answer

I got this error from my background service  I solved which creating a new scope                  using  var scope   serviceProvider CreateScope                                               Process

User · Answer

If your data has changed every once you will notice dont tracing the table for example some table update id   key   using tigger If you tracing  you will get same id and get the issue

User · Answer

I had the same issue  EF Core  while setting up xUnit tests  What  fixed  it for me in testing was looping through the change tracker entities after setting up the seed data   at the bottom of the SeedAppDbContext   method   I set up a Test Mock Context       lt summary gt      Get an In memory version of the app db context with some seeded data      lt  summary gt  public static AppDbContext GetAppDbContext string dbName          set up the options to use for this dbcontext     var options   new DbContextOptionsBuilder lt AppDbContext gt             UseInMemoryDatabase databaseName  dbName             UseQueryTrackingBehavior QueryTrackingBehavior NoTracking           Options       var dbContext   new AppDbContext options       dbContext SeedAppDbContext        return dbContext     Extension method to add some seed data   and detach entities in foreach loop at bottom of method       public static void SeedAppDbContext this AppDbContext appDbContext                  add companies        var c1   new Company     Id   1  CompanyName    quot Fake Company One quot   ContactPersonName    quot Contact one quot   eMail    quot one caomp1 com quot   Phone    quot 0123456789 quot   AdminUserId    quot  quot            c1 Address   new Address     Id   1  AddressL1    quot Field Farm quot   AddressL2    quot Some Lane quot   City    quot some city quot   PostalCode    quot AB12 3CD quot            appDbContext CompanyRecords Add c1                                   var nc1   new Company     Id   2  CompanyName    quot Test Company 2 quot   ContactPersonName    quot Contact two quot   eMail    quot two comp2 com quot   Phone    quot 0123456789 quot   Address   new Address        AdminUserId    quot  quot            nc1 Address   new Address     Id   2  AddressL1    quot The Barn quot   AddressL2    quot Some Lane quot   City    quot some city quot   PostalCode    quot AB12 3CD quot            appDbContext CompanyRecords Add nc1                 and so on                           last call to commit everything to the memory db        appDbContext SaveChanges              and then to detach everything         foreach  var entity in appDbContext ChangeTracker Entries                        entity State   EntityState Detached                  The controller put method The  ConvertTo lt  gt    Method is an extension method from ServiceStack   HttpPut  public async Task lt IActionResult gt  PutUpdateCompany CompanyFullDto company        if  0    company Id          return BadRequest        try               Company editEntity   company ConvertTo lt Company gt                        Prior to detaching an error thrown on line below  another instance with id          var trackedEntity    appDbContext CompanyRecords Update editEntity                     await  appDbContext SaveChangesAsync              catch  DbUpdateConcurrencyException dbError                if   CompanyExists company Id               return NotFound            else             return BadRequest dbError             catch  Exception Error                return BadRequest Error             return Ok       and the test       Fact      public async Task PassWhenEditingCompany                 var  appDbContext   AppDbContextMocker GetAppDbContext nameof CompaniesController            var  controller   new CompaniesController null   appDbContext              Arrange         const string companyName    quot Fake Company One quot           const string contactPerson    quot Contact one quot            const string newCompanyName    quot New Fake Company One quot           const string newContactPersonName    quot New Contact Person quot              Act         var getResult    controller GetCompanyById 1           var getEntity    getResult Result Result as OkObjectResult  Value          var entityDto   getEntity as CompanyFullDto              Assert         Assert Equal companyName  entityDto CompanyName           Assert Equal contactPerson  entityDto ContactPersonName           Assert Equal 1  entityDto Id              Arrange         Company entity   entityDto ConvertTo lt Company gt             entity CompanyName   newCompanyName          entity ContactPersonName   newContactPersonName          CompanyFullDto entityDtoUpd   entity ConvertTo lt CompanyFullDto gt                Act         var result   await  controller PutUpdateCompany entityDtoUpd  as StatusCodeResult             Assert                    Assert True result StatusCode    200              Act         getResult    controller GetCompanyById 1           getEntity    getResult Result Result as OkObjectResult  Value                   entityDto   getEntity as CompanyFullDto                     Assert         Assert Equal 1  entityDto Id      didn t add a new record         Assert Equal newCompanyName  entityDto CompanyName     updated the name         Assert Equal newContactPersonName  entityDto ContactPersonName     updated the contact    make sure to dispose of the  appDbContext otherwise running the full test will fail   appDbContext Dispose

User · Answer

public async Task lt Product gt  GetValue int id                Product Products   await  context Products AsNoTracking   FirstOrDefaultAsync x   gt  x Id    id           return Products          AsNoTracking

User · Answer

It sounds as you really just want to track the changes made to the model  not to actually keep an untracked model in memory  May I suggest an alternative approach wich will remove the problem entirely   EF will automticallly track changes for you  How about making use of that built in logic   Ovverride SaveChanges   in your DbContext       public override int SaveChanges                 foreach  var entry in ChangeTracker Entries lt Client gt                           if  entry State    EntityState Modified                                   Get the changed values                  var modifiedProps   ObjectStateManager GetObjectStateEntry entry EntityKey  GetModifiedProperties                    var currentValues   ObjectStateManager GetObjectStateEntry entry EntityKey  CurrentValues                  foreach  var propName in modifiedProps                                        var newValue   currentValues propName                         log changes                                                    return base SaveChanges            Good examples can be found here   Entity Framework 6  audit track changes  Implementing Audit Log   Change History with MVC  amp  Entity Framework  EDIT  Client can easily be changed to an interface  Let s say ITrackableEntity  This way you can centralize the logic and automatically log all changes to all entities that implement a specific interface  The interface itself doesn t have any specific properties       public override int SaveChanges                 foreach  var entry in ChangeTracker Entries lt ITrackableClient gt                           if  entry State    EntityState Modified                                   Same code as example above                                   return base SaveChanges            Also  take a look at eranga s great suggestion to subscribe instead of actually overriding SaveChanges

User · Answer

Without overriding EF track system  you can also Detach the  local  entry and attach your updated entry before saving        var local    context Set lt YourEntity gt         Local      FirstOrDefault entry   gt  entry Id Equals entryId        check if local is not null  if  local    null           detach      context Entry local  State   EntityState Detached       set Modified flag in your entry  context Entry entryToUpdate  State   EntityState Modified      save   context SaveChanges      UPDATE  To avoid code redundancy  you can do an extension method    public static void DetachLocal lt T gt  this DbContext context  T t  string entryId       where T   class  IIdentifier        var local   context Set lt T gt             Local          FirstOrDefault entry   gt  entry Id Equals entryId        if   local IsNull                  context Entry local  State   EntityState Detached            context Entry t  State   EntityState Modified      My IIdentifier interface has just an Id string property   Whatever your Entity  you can use this method on your context     context DetachLocal tmodel  id    context SaveChanges

User · Answer

In my case  the table s id column was not set as an Identity column

User · Answer

This error message can happen if you have duplicate entries entities and run SaveChanges

User · Answer

I faced the same problem but the issue was very silly  By mistake I have given wrong relationship I have given relationship between 2 Ids

User · Answer

Cant update the DB row  I was facing the same error  Now working with following code   context Entry  SendGridSetting  CurrentValues SetValues vm   await  context SaveChangesAsync

User · Answer

public static void DetachEntity lt T gt  this DbContext dbContext  T entity  string propertyName  where T  class  new        try            var dbEntity   dbContext Find lt T gt  entity GetProperty propertyName          if  dbEntity    null            dbContext Entry dbEntity  State   EntityState Detached        dbContext Entry entity  State   EntityState Modified          catch  Exception               throw            public static object GetProperty lt T gt  this T entity  string propertyName  where T   class  new          try               Type type   entity GetType            PropertyInfo propertyInfo   type GetProperty propertyName           object value   propertyInfo GetValue entity           return value            catch  Exception                 throw            I made this 2 extension methods  this is working really well

[c#] The instance of entity type cannot be tracked because another instance of this type with the same key is already being tracked

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